Taxonomy and identification of steamer-ducks (Anatidae : Tachyeres)

Taxonomy and Identification of

STEAMER-DUCKS

(Anatidae: Tachyeres)

Bradley C. Livezey and Philip S. Humphrey

u^C

^^, ^ Ernst Mayr lArary

- P ^ ^ %weiim of Compara»ve Zoology

Harvard University

THE UNIVERSITY OF KANSAS. MUSEUM OF NATURAL HISTORY

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f-'ninl Cover: ihc jour species oj Sieaiueriliicks asjollows: I pper lefi \\ liiieheiiiled I'll^^litlcss Sieanier-
(liicks (I'hoto;^rapli h\ R Siraiiei ki: Cpper rii^hl — Moiielluiue I- li;^luless Steamer -iliieks iPlioloi^rapli h\
D. /.immenmin): Lower left — iatklaiul l-'lii;li!less Slcamer-dueks I Plioloi;riiph In- B ('. l.i\e:e\): unci
Lower rii>lu — Llyliii; Stcamer-diiek (Photoiiraph by (!. L. Niieclilerlein).

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in

TtiK UNivi-;Rsin oi Kansas
Museum oi- Naturai. History

MoNOCK \I'H No. S

10 Docciiiher 1^)42

Taxonomy and Identification of Steamer-Ducks
(Anatidae: Tachxercs)

Bradley C. Livezey and Philip S. Humphrey

Museum (if Natural llisioiy

The ihiivcrsiix of Kansas

LawiciHC. Kansas hM)45-2454

USA

MUSEI'M OF Natlral Hisiorv

Dyche Mali

Thh UNi\r:RsiTV ni- K\nsas

Lawri \i I . K \nsas

MONOGRAPHS

EJilor fur litis issue: RiLluird [•. Jolinsloii
Mdiuiiiiiii; lulilar: Joseph "I'. Collins

MCZ

JUL 9 3
UNlVcI-SlTY

Monogia|ih No. S
Pp. i-l2.'i; 2y figures (2 in eolor); 13 tables: 1 appemiix
Published 10 December 1992
* ISBN: 0-89338-042-3

© 1992 H\ Ml sci'M or NAruRAr HisroKi

DVCHE Hali.

Till-: University or Kansa.s

Lawrenci;. Kansa.s 66045-2454, USA

Primi i> m

Usrvi Rsiiv oi Kansas Pkintini; Shrvick

l.AWR[-N( I . Kansas

contp:nts

INTRODUCTION 1

ACKNOWLEDGMENTS 1

METHODOLOCilCAL NOTES 2

Specimens -

Molls and Plumages 2

Measiiremenls 2

Slalistical Analyses 3

ORNITHOLOC.ICAL HISTORY OF THE STEAMER-DLICKS 3

Early Deseiiplions 3

Flighted and Flightless Species 4

A Second Flightless Species 1 1

A Fourth Species 12

Overview 14

SYSTEMATIC REVIEW 15

Relationships ol l\it. Iiwres 15

Synonomies lor lac hycres 16

Genus Tcuiiycirs 18

Flying Steamer- Duck tTachyercs piitachoniciis) 20

Falkland Flightless Steamer-Duck iT(i< hvcirs Ivuchyplcins) 27

Magellanic Flightless Steamer- Duck iTdclncifs piciicrcs) 30

White-headed Flightless Steamer-Duck iTik Incnw Icucm cpluiliis) 35

MOLTS AND PLUMAGES 36

History of Study 36

Comments on Descriptions 46

Ten llVCIVS pilhll hdiiicus 48

Tachycrc.s hnuiiyplcnis 54

Tacky crvs picncrcs 56

Tachycics Icmoccphalus 59

DIAGNOSTIC CHARACTERS 63

Generic Characters 63

Detennination of Age 65

Qualitative Characters of Species 67

Quantitative Characters of Species 75

KEYS TO IDENTIFICATION OF SPECIMENS 90

Skins 90

Skeletons 91

FIELD IDENTIFICATION 92

Introductory Comments 92

Ecological Segregation 92

General Appearance 93

Behavior 93

Vocalizations 94

STEAMER-DLiCKS IN CAPTIVITY 95

PROSPECTS FOR THE FUTURE 97

SUMMARY 98

RESUMEN 99

SPECIMENS EXAMINED 101

LITERATURE CITED 105

APPENDIX 121

INTRODl'CTION

Durmy our leii-scar stLkl\ ol the sieaiiicr-diiLks
{Tcichycrc.s ). a moderately speeiali/ed Soulli Aiiici i-
can genus of shelducks (Tadorninae: IJve/es
1986a). our piiniar\ inierests have lieen llie mor-
phological bases and adapli\e signiticanee ol
tlighllessness. geographic variation, sexual diiiioi-
|ihisni, and phylogenetic relationships ol the loui
species. ,-\s these investigations progressed, hovv-
e\ei-. :t became apparent that basic taxoiiomic
issues, including alpha-ta\ononi\ and the ilesig-
nation of types, and the data and techniques asso-
ciated with identihcation of specimens, required
attention. Taxonomic difficulties ha\e |ilagued the
study of steamer-ducks since their discovery in the
late sixteenth centur\. and certain of the present-
tla\ problems in s\steniatics of the genus ha\e
their origins in this history of controversy. This
state of affairs is in part due to the three most
salient characteristics of the genus Tacliycrcs: { 1 )
large si/e. which exacerbated the difficulties o\
collection and study of specimens; ( 2 ) widespread
flightlessness. an often conspicuous characteristic
thai principally created taxonomic conlusitm; and
[?i) drab gray-and-white plumage, which offered
fev\ clues to the recognition and diagnosis ol
species. The taxonomy ofTiichyens also has been

prone toinersmiplilicalion ("lumping ol s|iecies'").
ap|iarentl\ because of the traditional view that
s|iecies of waterfowl should be reatlily distin-
guishable using plumage characters, even under
held conditions.

Ihe present pa|iei has six major objectives: ( I )
to present a history of the study of the genus.
v\liich in turn will provide an insight into the
complicated taxonomy that has been applied to its
members; (2) to provide generic aiul specific syn-
onviifies and species accounts; (.^i tii present the
a\ailable information on the molts and plumages
of 7(/(7;\'('/(',s: (4) to cimipare the diagnostic char-
acters of the four species and to construct keys to
the identification of specimens; (."i) to summari/e
information on field identification aiul asiculture
of steamer-ducks; and lb) to present a subject-
indexed bibliography of the considerable but scat-
tered literatLire on steamer-ducks. Our hope is that
the work will enable ornithologists, some of whom
have shared with us their concerns, to identify
steamer-ducks in the haiul anil (uinler giiod condi-
tions) in the field. Should this endeavor prove
successful, we anticipate that these unique birds
will receive the continuing siiidv that they de-
serve.

ACKNOWLEDGMENTS

Our research on steamer-ducks was supported
during 1980-85 by National Science Foundation
grants DEB-8()-1240.\DEB-8 1-1 7942. and BSR-
83-199{)(). the Kansas University Endowment
Association. Southwestern College, the British
Broadcasting Corporation. W. Saul, M. C. Thomp
son. L. A. Osborne. R. T. Peterson. T. Mastm. K.
Hamilton, and the Humphrey family. Livezey also
was supported in part by NSF grant BSR-85 I6b2.v
Collecting permits were issued by E. O. Gonzalez
Ruiz (Direccion Nacional de Fauna Sylvestre.
Argentina). L. O. Saigg de Chiaha (Proteccion
Ambiental. Chubut. .Argentina). D. H. Soria
(Ganaderia. Santa Cruz. Argentina). E. Cruz
(Servicio Agricola y Ganadero. Chile), and Sir R.
Hunt (Civil Commissioner. Falkland islands ). Field
work in Argentine national parks was made pos-
sible by .\. Tarak (Direccion Nacional de Parques
NaciiMiales). Logistic support was provided by J.

M. Gallardo. R. A. Bockel. and .1. Navas (Museo
Argentino de Ciencias Naturales. Argentina). G.
PincheiraandT. G. Iriarte (Universidad de Chile),
and M. M. L'Huillier. D. Bersalobec. S. Canessa.
C. Montenar, and D. Nunez D. (instituto Profes-
sional de Osorno. Chile). Essential arrangements
were made by G. A. Giaroli. F. Liibhe and F. Villar.
Housing and laboratory facilities were arranged
by O. Kuhnemann, D. Nunez D.. P. Medina, and J.
Sesti; B. Mayer and F. V. T. .1. Fauring provided a
home and field support at Puerto Melo. Logistic
help and friendship were provided in the Falkland
Islands by A. F. G. Douse (Stanley ) and A. and Y.
Davis (Lively Island). We also are grateful for the
assistance and hospitalitv of B. Rosso. L. Orquera.

E. Plana. G. Piacentino, J. E. Bonczak. R. E.
Caferata. A. Fernandez. R. Landivar. G. C. Sarccda.

F. Erize. R. Straneck. W. Conway. Y. Lucero. P.
Canevari. M. A. E. Rumboll. R. Hall. H. Niemever.

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. S

M. SallalxTiv A.. A. Veloso. J. Ballastcros C. and
the (iihson I'amily. Spcciiiicns were made avail-
able by tlio l-icld Museum of Natural History
(Chieago). British Museum of Natural liistor\
(Tring). American Musemn of Natural llistor\
(New York). San Diego Museum of Natural His-
tory, Peabody Museum of Natural Flistory (Yale
University). Museum of Comparative Zoology
(Harvard I'niversity ). Museum of Zoology (Llni-
versity of Michigan), and U. S. National Museum
of Natural History. R. Straneek (Laboratorio de
Sonidos Naturales. Museo .Argentino de Ciencias

Naturales. Buenos Aires) prin ided tield record-
ings of vocalizations of steamer-ducks, and J. W.
Hartiy (1-lorida State Museum. Gainesville) pre-
pared sonograms of selected recordings. I'npub-
lishetl observations of steamer-ducks inciirporated
into the liistribution maps were pro\ ideti by P.
C'anevari. J. C. Chebe/. X. Ferrer. O. Kiilinemann.
T. Narosky. M. Nores. and R. Straneek. We also
thank R. Mengei. M. Jenkinson. and their col-
leagues ft)r preparation of speciinens; P. Rasmussen
for executing Figure '->: and K. McManness, K.
C'orbin. and M. Schmal/ for t\ ping.

METHODOLOCilCAL N()TP:S

Specimens

Much of our work on steamer-ducks has been
based on observations made and specimens col-
lected during our Held v\(nk. We made five trips
during 1979-84 (the first with Max C.Thompson),
gained first-hand experience w iih all four species
ofTachyeres. and for all but /'. Icticuicpluiliis we
studied each at several localities. By species and
locality, these were: T.palaclutiucus — Puerto Melo,
Lago Fontana, and lagos Futalaufquen and Kriigger,
Chubut, Argentina; Puerto Deseado, Lago
Argentino. and lagos in Parque Nacional Perito
Moreno. Santa Cru/. .Argentina: Ushuaia and
Lapataia, Tierra del Fuego, Argentina: Bahia de
Ancud, and nearby lagos Llanquihue and Rupanco,
Region X. Chile: 7'. hravhypicrus — Lively islaiul
and Port Stanley, [•'alklaiul Islands: I'.
Icucocepluiliis — Puerlt) Mek), Chubut, Argentina;
7'. plcneres — Ushuaia and Lapataia, Tierra del
Fuego. Argentina; and Bahia de .-Xncud. Chile.
These specimens and associated data were aug-
mented by specimens studied at other institutions,
which contributed greall\ lo the localities rejire-
sented. A complete listing of the specimens exam-
ined is given in a later section.

Moi IS \M) Pi I m\(;ks

Description of plumage patterns useil the color
scheme of Palmer (1962). Downy yoimg were
assigneil to age classes using standard criteria
tietaik'd ni llumphiey and l.i\e/e\ ( I')S.'i:')4.'S ).

Measurements

Masses were measured w ithin 1 2 hours of col-
lection of the birds using spring scales. Most skin
measurements used are standard (Baldwin ct al.
I9.il). although a few comments are needed.
Sample sizes for tail lengths are comparatively
small because we collected this datum only in the
latter half of the field work, and because of a
relatively high frequency of specimens with worn
or missing rectrices. Lamellar counts were the
total number of lamellae (regardless of size) on
one side of the upper bill of a fresh bird: counts in
dried skins may not be reliable because of reduced
visibility and shrinkage of lamellae. Wing areas
were estimated b\ doubling the area (using
planimeter) of the tracing of an extended wing.

Skeletal measurements are largely self-ex-
|ilanalory, but a fev\ warrant description. These
include some of the skull measurements: cranial
height m;L\imal distance from dorsal surface lo
ventral surface of braincase: cranial length —
distance along midline from frontonasal suture to
posterior of braincase: postorbital w iilth — maxi-
mal width of cranium, measured on the lateral
processes of quadratojugal bones: antorbilal w itlth
maximal distance across the antorbilal processes
ol the laciymal bones: frontonasal width — dis-
tance across lostrum at trontonasal suture: skel-
etal height, length, and width ol bill — measured
as on skin but base of bill delined as frontonasal
suture. Head wiilth of the Innnerus is the maximal
bicadlli of the element al ils proximal end. I lead

STEAMER-DLIC-KS (ANATIDAE: TACHYERF.Si

wkIiIi III ilic lemur is the uullh ot ilic pioxinuil
L-iul will) lliL- lic.id 111 the bone oriented jierpen-
diciil;irl\ to the ealiper surface. Tihiolarsiis leiiglh
iiieludes that of cneinial crest. I, east widths at
midpoints (LWMs) were measured on si\ major
limb elements.

Osteological iiomenelature follows Baumel ci
III. ( 1^'?'-)) with alleiiiate icrminolotis of Howard
( 1424) given in parentheses.

Statistical Analysks

LInivariate comparisons were made using two-
wax analysis of variance (ANOVA). E.xcept for
masses, areas, and ratios, which were loy-trans-

fornietl for anahsis. all statistics were based on
rav\ data.

Discriminant functions and canonical analyses
were used to contrast species using suites of mea-
surements (Pimentel 1474). Analyses were per-
formed on raw data: analyses based on log-trans-
formed (base (■) data produceil virtually identical
results and affected no inleiences or interpreta-
tions, (-or multivariate analyses ol skeletons, we
used a program for estimation of data missing
because of bilateral breakage or deformity: these
estimates composed less than \'^''( of any data set
analyzed.

All programs used were part of the Biomedical
Computer Programs (Dixon 14SS).

ORNITHOLOGICAL HISTORY OF THE STEAMER-DUCKS

EaRI ^ DkS( RIPTION.S

In I .'iS2. Pedro Sarmiento de Gamboa observed
an unfamiliar duck in the Straits of Magellan,
which inspired the following description ( I X4.'i:.S3;
translation o\ Sarmiento de Gamboa I 76S ): "in the
water they cannot rise but by their feet, using their
pini(Mis as oars. They thus go through the water
w ith great velocity, and they leave a track like that
of a boat when propelled by oars. Their velocity is
so great that a good boat under sail, with a fair
wind, cannot overtake them." Eighteen years later
in the Straits. O. Van Noort (1426:4S) noted as
common a flightless "goose" in Goose Bay. Dur-
ing passage of Captain Wood through the Straits in
1664. Hacke {1644:60) observed "...great Blue-
Dticks. which are not very shy."

,\ number of subsequent voyagers to the Straits
and the l-'alklaiul Islands wrote of these large wa-
terfowl and their characteristic, spray-prodticing
method of surface locomotion, most referring to
them as "race-horses" or "loggerheads" (Pernety
1764:370: Byron 177,^:50: Hawkesworth
1773:41 1-f 1 2: Penrose 1 775:3.*S: Clayton 1774:40.
1776:104: Cook I777:IS6. I77S:27: Elliott and
Pickersgill 1 4X4:34). Whether the name "logger-
head" w as based on the phy sical appearance of the
birds or their pugnacious behavior is not clear.
Byron ( I773:.^0-.^I ) described them as "...a bird
much lariier than a eoose. which we called the

racehorse, from the velocity with which it moved
upon the surface of the water, in a sort of half
Hying, half running motion." Most early accounts
were distinctly culinary in perspective. Penrose
( 177.S:3.'>-36) wrote: "One kind of duck however
we had. which was by no means a delicacy: we
called it the loggerhead, for an obvious reason: and
it seemed to be a large species of the Muscovy
\Cciiiiihi mosclhitci] sort, only its w ings resembled
those of the penguin: as these ducks. ..were utterly
tillable to fly. our method was to drive a large team
of them together into some delile. and then to
knock down as many as we had occasion for. The
use we put their flesh to was to boil it well in the
copper, and then to give it to our pigs... .and though
this mode of fattening may appear rather intleli-
cate to some people, yet it is astonishing how the
hogs thrived with it." Clayton ( 1776: 104) reported
similar exploits: "But here is a species of ducks,
called the loggerhead, from its large head. They
have short wings, are unable to lly. anil only swim
and flap along on the water at an extraordinary
rate. When driven ashore w ith boats ihey run fast,
but soon squat down and are easily caught: they
are eatable, but are but indifferent food: thev are of
a dark brown dirty colour." Cook ( 1777: 1 N6) also
described the locomotor behavior of the birds:
"Here is a kind of duck, called by otir people race-
horses, on account of the great swiftness with
which lhe\ run on the water: for thev cmnot 11 v.

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

ihc w ingsbciiiu loushDil losiipporl the botis in iIk-
air." C(Hii<, evidently wiilunn the benclil ol' per-
sonal e.xperience. was less critical ot'tiie palatabil-
ity of the ducks, writing (p. 205): "We shot some
I race-horses I . anti lound them to weigh twenty-
nine or thirty pounds; liiose who eat ot ihem saiti
they were very good."

Molina (1782:239) may have relcrred lo this
duck (known locally as the "quethu ") trom C'iiiloe
Island (Chile). Murphy ( 19.^6) justihably doubled
the relevance ot'the binomial name used by Molina
(Dionu'dca chilocusis). one based on an inad-
equate description and suggesting a relationship
with tile lubenoses (Procellariiformes). Tlie au-
thors of two of the earliest global faunal compila-
tions referreil to the bird only by the vernaculai'
names used by voyaging naturalists (Latham
1 785:43'): Buffon 1 798: 1 59). Beginning with nam-
ing of the "loggerhead" nsAiuis ciiicrca by dmelin
(1788:506). a species name later rejected as lui-
available by Murphy ( 1936). the species, as then
construed, was given six tlilTerent binomial names
before its monotypy was questioned, l.alham
(1790:834) applied the lirsi species name to be
found available by later taxonomists — Aiuis
hi\u InjUcra.

King ( 1828:100) initially named specimens of
the group as OiJcniia jHihichonica. describing the
birds as forty inches long, jiredominantly gray
with white specula and abdomens, having yellovs -
orange bills with black nails, yellow legs, anil
wings with a blunt spur at the bend. King( 183 1:15)
later distinguished anoihei' species. Mkioptvi iis
paiachouiciis. that was more red-colored on the
throat and scapulars, had a greenish-black bill, ami
was smaller than its congener M. hru( lixpicid
\sit\. evidently releiring to .\;;(/,v hrocliypicid
Latham (1790:834). mentioned by Quoy and
Gaimard ( 1824:347). King ( 1839:36) was not en-
thusiastic about their jialatability. wiiting: "Ihe
flavor of their llesh is so strong and tish\. thai at
lirst we killed ihem soleU lor specimens. \\w or
six months, howeser. on salt provisions taught
many to think such fooil palatable, anil the seamen
never lost an opporiunii\ of eating iheni. I ha\c
preferred these ducks to salt beef, as a piescnii\e
against scurvy rather than from liking theii lasie. '
Kins: ( 1839:542) also clantied the taxononnc dis-

tinction, listing Oidcmui patculumicci as a syn-
onym for flightless Mitroptcrns hiachyptcnis. and
added to his description of the smaller species i.M.
pdnic/iniiiiiis) its abilit\ to th. Ihe reapplication
of the wdmc pdiacliniiic IIS to the tw o species recog-
ni/ed by King, an action with important nomen-
clatiual implications (Live/ey 1989b). evidently
stemmed iVom his partiality to a name appropriate
lor a bird "Patagonian in stature. ..as well as in
station..." (King 1828:100). This taxonomic deci-
sion marked the beginning of a century-long orni-
thological controversy concerning the existence
of both Hying and flightless species of steamer-
duck, so named by King (1839:35) because of
their resemblance to paddle-wheel steamships
w hen "steaming" across the water surface.

FiJCHTKI) AND Fl.KJH ILKSS Si'KCIKS

During the period from 1830 to 1861. must
naturalists, some familiar with steamer-ducks in
the lield, mentioned only the flightless taxon in
their works ( Darwin 1 839a: 1 90, 1 839b:257; Gray
|S40:74. 1849:623: Forster 1844:338: Gray
1S44:14(); Gould 1841:136. 1859:96: .Strickland
1841:.39: Hartlaub 1846:19: Des Murs 1847:457:
Lichtenstein 1854:100: Boeck 1855:511:
Bonaparte 1 856:65 1; Germain 1860:315; .Selater
1860:389. lS61a:367). Eyton (1838:144) listed
both species, but stated, without reference: "Both
aie destitiUe of the |iowers of flight, merely using
their w ings to flapper over the surface of the sea."
I le also admitted to having "considerable doubts"
as to the validity of recognizing two species. I^ar-
win { l839a:257-258) observed steamer-ducks in
the I'alklaiiil Islands ikuing his \oyage on the
'Beagle' and wrote: "In these islands a great
loggerheaded duck or goose (,\/((/.v hnnliyptcia).
which sometimes weighs twent\-two pounds, is
\erN abundant. Ihese birds were in lormer ila\s
called, from their extraordinar\ manner of pad-
dling anil s|ilashing upon the water, race-horses:
but now the\ are named, much more appropriately,
steamers. Their wings are too small and weak to
.illow ol flight, but b> their aid. parll\ swimming
and parti) flapping the surface of the water, they
move very quickls'. The manner is something like
that b\ which the common house-iluck escajies

STEAMHK-DliCKS (ANATIDAE: TMHYERES) 5

vvlien pursued h\ a ddg; bill I am iK-arlN sure lliat iX7lh:44-y3; lS71c:262) posiulaled lluil iheie

the steamer nun es its w ings alleinalel\, msiead (il was only line speeies ol sicanier-iluek, aiul lliat

botli loszether. as in other biixls. I'liese cliunsy. tlyiiit; individuals vveie but adolesceiils that with

louueiheaded ducks make such a noise and s|ilash- maluril> would become too heavy for tliylit.

iiiL;. that the elTect is exceedmgh curious. ...The Cunningham baseil this conclusion on the lelalive

steamer is able to dive only to a very short dis- ossilication ot eight specimens: two partial skel-

tance. It feeds entirely on shell-fish Ironi the kelp etons and two crania of '"adult" (presumably

aiul tidal rocks; hence the beak aiul head, for the llightlcss) intli\ uluals; two skeletons of "imnia-

purpose of breaking them, are surprisingly heavy ttire" flying birds; and two crania of unfledged

and strong: the head is so strong |see Fig. I | that I young. He noted that his specimens of "adult"

have scarcely been able \o fracture it with m\ birds were gray with orange-vellow bills, whereas

geological hammer; and all our sportsmen soon "younger" birds (his /)i//(((7/()/(;(/(.sMvere smaller,

discovered how tenacious these birds were of life." more red-colored on the throat and scapulars, and

Two decades later, in 77;c Orr^i/i <// .S'/'<t/c.\, Dar- hadgreenish-black bills. Cunningham ( IS71a:4y.^-

win( 1 8.'i9:2()6) described the "logger-headed duck 444) concludetl from an examination of this mate-

{Micropicni.s of Eytonl" as using their wings rial: "My principal reasons for this conclusion are.

"solely as flappers." imphing that all steamer- that the flying and flightless biixls associate to-

ducks were flighlless. gether. that the former are smaller in si/e than the

However. Abbott ( I S6I : I (i2)defendetl the spe- latter, and that I have invariably found the skel-

cific distinction between flying and flightless etonsof the volant individualsto present unequivo-

steamer-ilucks made by King ( IS3I: l.'i). based on cal traces of immaturity, while, on the other hand,

experience with both forms in the Falkland Is- those of the non-volant were constantly found to

laiuls. This promptetl at least one brief, if apolo- be fully ossihed. I believe, therefore, that as the

getic. mention by Sclater (lS6lb:46) that there bird increases in size and weight, owing to the

might be two species of steamer-duck. Abbott deposition of an increased amount ofniineral matter

( IS6I : Id2) also reported a nest of the flying spe- in the bones and various other causes, it gradually

cies, an observation that was to be disregardetl by abandons the habit of flight, finding that the speed

most subsequent workers. Cox (IS63:I74. 2.^?) with which it can progress through the water by

added to this evidence through his observations of means of the rapid movements of its wings, to-

llighiless steamer-ducks on the seacoast and nu- geiher with its diving-powers, are sufficient to

merous fl\ ing steamer-ducks on freshwater lakes, preserve it from threatened danger." However,

but did not distinguish the forms taxonomically. even Cunningham unintentionallv revealed some

In the summer of IS66. A. Newton persuadeil lingering doubts, or at least confusion. In a de-

R. O. Cunningham, during his forthcoming trip to scription of the sternum of flightless steainei-

the Straits, to ascertain whether or not two species ducks he (IS7la:4MS) wrote: "...In ihliili ypccics

of steamer-duck existed (Cunningham IS7 la:49.^). the posterior border is more deeply excavateil than

During the trip. Cunningham (IS6Sa:l27; in adolescent (flying) birds |emphasis atkleil |."
IXbSb:4^)|) observed that some indisiduals of The hypothesis proposed by Cunningham was

Miciopicrus riiicreu.s could fly whereas the heavy received fairly well. (Sclater and Salvin I S76:4().^.

weight of others precluded flight. However, men- IS7S:4.^7; Sclater IXSI:I()7. lOS; Vinciguerra

lion of flighted steamer-ducks was cons|iicuously 1SS3:.SS; Sharpe f S^) I :.^l)'-*; Martens l')()():2.^:

absent from most other published discussions of Evans l'J()y:12l). although thereafter until the

the genus for the next eight sears (Pel/eln lS(i.'S:l.^9: early l^OO's most proponents of his one-species

Schlegel lSfifi:l.v I IX: 1X72:274: Sclater h\p()thesis did not cite his explanation, but simply

1S67:.33.S. 340; lX6X:?2y; Cnglioli IX6X:4yX; continued to exclude mention of the flying form

Philippi IX6X:2S3. 309; Sclater and Salvin from their works (e.g.. Thomson I X77:2(),S; Spr\

1868:189; 1X70:499; Gray I S7 1 :XX). 1X79:293; Reichenow IXX2a:4X; Hyades

UltimatcK Cunniniiham ( I X7 I a:493-494; 1 XX3: 1 343; Tristram I XX9:47; Moselev 1X92:480;

UNIV. KANSAS MUS. NAT. IIISI. MONOCIKAI'M NO. S

Lalaslo IN93:I22; Ciadow 1402: UiM; Oatos
1 y()2: 1 .S4: Nicoll 1 904:49: P> crall 1 906:40 1 : Reed
1907: 103: Cobb 1910:66: Beck 191 S:S|. The one-
species view was solidified subsianlially by the
endorsenienl given il by Owen ( I K7.'i:2.'S4. 266) in
his replacement of the (nionolypic) generic name
Miiroplcnis (erected by Lesson 1S2S:416) with
the currentlv used Tacliycrcs (from the Greek.
Taxviilpil^ meaning "swift rower"), because of
the previous application of Micmpieriis to the
North American freshwater basses. This change of
genus was adopted by Sharpe (1899a). Although
Owen ( 1 S7.'i:2.'i4) used the binomial ta.xon
Tcnljycrc\ hriniiypU'iiiy in erecting the genus, most
taxonomistsof the "one-species" school from 1876
until the early 19()()"s instead used the name
Tacliycrcs cliwrciis to refer lo the group.

Despite widespread acceptance during this pe-
riod of the view that there was but one species of
sieamer-duck. held observers, convinced of the
existence of both flying and flightless species,
published their views with increasing frequency.
Giglioli ( 187.^:9.^4) was |iersuaded thai two spe-
cies existed, and even suggested another, but con-
tradictory, binomial name for the flying form —
Micrtiptcnis iiiucrupicnis. Coppinger (1883:61-
62) observed flying steamer-ducks mostly on fresh-
water lakes and flightless birtls on saltwater, and
noted that color of plumage and bill distinguished
young flightless birds from the flying form, in
opposition to the model presented by Cunningham.
Although not discussed in the literaliue. two poorly
ossitied skeletons of juvenile flightless steamer-
ducks, which alone could have disproveti the de-
velopment-related hypothesis of flightlessness.
were collected in 1888 on the ""Albatross Hxpedi-
tion" and deposited in the LI. S. National Museum
of Natural History.

Ousialet (1891:8212-2.^2), prompted by held
observations and specimens collected near Cape
Horn, including osteological comparisons, rel uteil
the view of Cunningham and treated the Hying mu\
flightless forms as distinct species, tievoting six
teen pages to the description of the former: Oustalei
includeti. however, several mediiuii-si/ed. rela-
tively short -winged birds from the l-alklamls in his
M. pahichoiiiciis (see table on p. 2 I ."^ i. In addnion
to arizuments based on analoinical differences.

disiribulions. and locomotion. Ousialet (pp. 2 1 .V
214) pointed out that the frequent association of
the two forms in flocks is not rele\anl to the
question of their possible conspeciticily.

.Several museum taxonomisis and anatomisis
also showed less than complete acceptance of the
theory ol Cunningham. In an exhaustive synonymy
of the genus. Salvadori (189.^:37.^) recognized
only one species ( Tacliyeres cincrciis ) but acknowl-
edged the observation of Cox ( I86.^:2.^.'S) of nu-
merous flying Mi( niprcriis cincrciis on the .Andean
lakes. Schalow ( 1 898:672-674) reviewed the taxo-
nomic debate and considered the plumage charac-
ters given by Oustalet ( 1 89 1 ) Ui be inadequate for
diagnosis; like Salvadori (189.S). .Schalow listed
only T. cincrciis. Beddard (1898:4.^7). although
evidently accepting the basic thesis of Cunningham,
found no greater density of bone in flightless
steamer-ducks than in other vvatertovvl. Newton
( 1893) stopped short of complete endorsenienl of
the theory proposed by Cunningham, and he
Il893:.'i97) even suggested the unprecedented
notion that the flightlessness of Taclncrcs was
relatetl to the molt of the remiges.

After the turn of the centur\. the controversy
became more pointed. Dabbene ( l'->()2:403) con-
sidered the one-species hypothesis iif Cunningham
( 1871a), but rejected it based on the discover) of
a fully ossified steamer-duck specimen that dif-
fered anatomically from flightless birds and "'cor-
responded perfectly"" with the flying Micropicrus
patdihoniciis describeil by Ousialet (IS*-)!).
Dabbene ( 19()2:4()4-4().^) went so far as to con-
sider the fl\ ing and flightless forms to be generi-
callv disiinci — Micrnpicnis p<i!iicli<>niciis and
Tacliycrcs cincrcits. respectivelv.

Crawshay (1907:110-115) treated living and
flightless steamer-ducks of Tierra del Fuego as a
single species (Tacliycrcs cincrciis). concluding
that (pp. 110-111): ""The question of whether one
or two s|iecies are to be admitted has been final Iv
delermiiicd in lav our of one in the opinion of the
majorilv....! do not think I came across one
I sheepman I whohaddefinitelv aniveil al iheknowl-
eilge that the powerof flight could be possessed by
some individuals ami lacking in others."" Nicoll
I l')l)8: 17 1-172) sLipportctl the view .ulvancetl bv
Ciiiinini.'ham. olleiiiii: ihe follow Iiil; ralionales:

STEAMER-DUCKS (ANATIDAE: lACHYERES)

"All the examples we obtaiiiccl. ami all those I
ha\e examined in Ihe British Miiseiini. iimloiibt-
edly belling to one speeies onh: and it I nia\
ventine to give an opinion. I should say that Pio-
I'essor Cinininghani's is iiiuioiibiedlx the right so-
Uitiiin. as it would surel_\ be an almost un|iree-
edented thing to tind two very nearly allieii s|iec'ies
living together, one able to fly and the other unable
to do so. At the same time, it is somewhat remark-
able that, although we saw examples of this duek
of all ages and mall stages of deselopment. we met
with but one w hich was able to fly. It may be that
this species is gradually becoming entirely
flightless, and that the \ olant indi\ iduals met w ith
are sur\ ivals of a former stage in a stale of transi-
tion, and have not as yet lost the full power of
flight." Paessler (14(W:|{)3) also believed that
steamer-ducks comprised a single species, although
he had seen some individuals fly for .'iOO-IOOd
meters w hen pursued. Scott and Shaipe ( I *■) 1 2:4M2 ).
after an examination of specimens of steamer-
ducks in the British Museum and Ihe Museum of
the Jardin des Plantes. including those identitied
by Oustalet (l<S9i) as flying Mnropierus
paiachdiiicits. conc\uded. as had Cunningham, that
flying individuals are the young members ol a
single speciesof steamer-duck, the adults of which
are flightless. They (p. 492) also described plum-
age patterns and soft parts of these ■"immature'"
birds, thereby hypothesizing a molt sequence to
account for the plumages described by Oustalet
( ISMI ) for T. pukn liciiiciis,

Blaauw ( im2a:46-4y). in a narrative of his
voyage through the Straits of Magellan in 1911.
became the leading proponent of the two-species
view during the first two decades of the twentieth
century, in two papers about this expedition, he
(191 2a:46-f9. I 9 1 6:4X,S-492 ) established several
important points thai contradicteil the traditional
one-species hypothesis: (I) flightless steamer-
ducks are distinctly larger than the flying species:
(2) young of the flightless T. ci/icirii.s are as
flightless as the adults; (3) flightless steamer-ducks
are confined to the sea whereas the fl\ing species
frequent both fresh and salt water: (4) sexual
dichromatism is much less pronounced in the
flightless species, in which the adults of both sexes
have sirav heads and orant:e-\ellow bills, than in

ll\ my birds, in w Inch aikill males ha\e gi"a\ heads
aiul orange-\ellow bills but females have brown
heads and dark-colored bills; (.^ ) the flying species
is much smaller and browner in plumage than the
flightless form, although both species have a white
speculum; (6) members of the flying species also
■"steam" across the water like the flightless birds.
bLit 1.I0 so more buoyantly.

Brooks ( 1 9 1 7 : 1 5."!- 1 ."iy ) attempted to reconcile
these observations with his own of steamer-ducks
in the Falkland Islands, but had little success. He
reported that (p. \5(i): '"Among many hundreds of
these ducks seen in the F-alklands. all. except
perhaps in size (Mr. Bkuuiw gi\es no measure-
ments) answer absolutely his description of what
he diagnoses as T. patacluuucus. No birds of dark
plumage, the females, even \sic\ had yellow bills,
ami no females were seen in anything that could
possibly be referred to as a gray plumage. And out
of many hundreds seen none took flight, although
1 do not doubt for an instant that a small percentage
can fly." Brooks ( 19 I 7: l.'i.S) concluded: "There is
no doubt in m\ mind that there are both flying and
non-llying steamer ducks, but how they are to be
satisfactorily separated and diagnosed remains a
task as yet unaccomplished." Sclater ( I9I7:62{)).
then editor of The Ihis. commented on the ■■vexed
question" debated by Blaauw and Brooks, and
concluded that "...the whole mailer still remains
obscure."

In that same year. Phillips ( 191 7: 1 I 7-1 I S )
quoted at length from a letter (dated 14 August
1916) in which Brooks went further (p. I IX; em-
phasis in original):

"Wc arc worse off lluin ever. His i- pauu honu ns
agrees in appearance with the only birds (perhaps
thousands) that I saw on the Falklands. His T.
< inereiis. v\ith orange-yellow bill in both sexes,
perhaps does not exist at all. Is it not very rare in
Ducks sexually unlike in colour to both have the
yellow bill which so often characterizes the male?

■■1 rather doubt if these birds can ever be satis-
factorily differentiated, for it seems to me that this
species is in the midst of its transition from a flying
to a non-flying form, as in the Falklands it cer-
tainly exhibits every stage from mere flapping to
flights from nest to the w ater. probably not greatly
exceeding half a mile. It would surprise me if a

UNIV. KANSAS MUS. NAT. HIST. MONOtiRAPH NO. 8

satislaclory line ctuikl be drawn ansvvheie. Obvi-
ously the flying birds are greatly in the minority
throughout its r;nige.and ifnioree.xisi inTierradel
Fuego and southern Patagonia, it may be because
it has become necessary in a region where for ages
they have had primitive man and other natural
enemies to contend with."'

Phillips (1417:1 l,S-llt)) followed this excerpl
with his own opinions, based only on the reports
and specimens of others:

"First, then. 1 should ihnik that the theory olDr.
Cunningham, which connects volant power with
adolescence, must certainly go by the board.

"Second. Volant steamer ducks appear to be
more common on the mainland and on Tierra del
Fuego than on the Falklands.

"Third. The power of flight may be associateil
with a differenl si/e and different plumage, but
this fact has not been clearly demonstrated.

"Fourth. The Falkland Island Steamer Ducks
are well differentiated as to sex. The males are
large and light coloured (apparently getting lighter
with age) and have yellow bills (at least in the
breeding-season). The females are smaller,
browner, and have dark bills,

"Fifth, The species seems to be on ihe boiiler-
land as concerns its power of flight, Fven in non-
flying birds there is a marked variation in the
ability to use the wings,"

Blaauw ( 1917:274-276) replied to these criti-
cisms with equal confidence, reaffirming the va-
lidity of his diagnoses and questioning the basis
for the doubts expressed by Brooks and Phillips.
He wrote (pp. 274-27.'i):

"It seems evident thai Mr. Phillijis' collector,
Mr, Brooks, has only seen one species of steamer-
duck and that Tachycrcs palaclioiiiciis.

"Mr, Phillips has therefore experience ol unc
species only, and accordingly it may perhaps be
doubted if he can reasonably talk with authoriiv
about i\\i>\ Mr, Phillip's collector has only been lo
the Falkland Islaiuls, which are a siionghold of
Tachycrcs luiuicliniiicus....

"That Mr, Brooks has not seen /. jnitiU lioniais
fly and could not make them lis although he has
seen "thousands." notwithstanding thai those birds
were, judging I'rom his descriiition. really /
paliK li(>iii( lis. oiilv lends lo |iro\ e thai Mr. Brooks

has either exceptionally bad luck or was not able to
identif) those birds when seen on the wing,"

Evidently, it occurred to neither lilaauw nor
Phillips that a population of flightless, sexually
dichromatic steamer-ducks similar in aspect to /'.
Piihiclioiiiciis inhabited the Falklands.

Mogensen ( I917:84-S.'^). indcpeiulentlv of
Blaauw. was convinced that two anatomically dis-
linguishable species of steamer-ducks occurred on
ihe continent. He noted that both sexes of the
flightless species have grey heads and yellow-
orange bills; w hereas in the flying species only the
male is so colored, the female being darker in the
head and bill. Mogensen also observed that the
flightless species is limited to sea coasts, but Ihe
flying species can occur in both fresh and salt
w ater. and in the latter both species often occurred
logether. He even provided measurements to dem-
onstrate that the wings e)f flying T. pnuiclwnicus
were longer (.^4-36 cm) than those of heavier,
flightless T. ciiicrciis (26-28 cm).

Qualihed support for the two-species view also
was forthcoming from observers in the Falkland
Islands, Wace ( 1921:201 ) reviewed the literature
on the controversy and. although he went so far as
to neat the flying form as a taxonomic variety
paiiiclioniciis of the single species T. ciiicrcii.s. he
concluded by reviving the idea that flying birds are
the lighter-bodied adolescents ol Ihe flightless
species, Vallentin ( 1924:322-328) concluded that
(p, 324): "According to my observations there are
two species of Microplerus lo be lounil in ihe
I alklamls, and those accurate observers. Captains
King and .Abbott, were absolutely correct in their
brief diagnoses," Vallentin ( 1924)expliciil> listed
onl_\ y , rincrciis for the Falklands (p, 322). as in his
previous works (Vallentin 1901:3.'i(): 1904:33):
however, he referred (p, 32.^) to "the "Flying Log-
gerhead". .U. piitdcluiuicus (King)" in the text,
reported having flushed several flying steamer-
thicks from nests located well inland, and noted
ihai lhe\ had proportionately longer wings and
more oval eggs than the flightless form,

1 he situation in the Falkland Islands was clari-
lied significantly by the observations ol' Bennett
( 1924. 19261. although evidenlh his contribution
largelv was ignored hv sLibscqiieni woikers,
Bennell ( 1924:2S()-2S2 ) provided mensural com-

STEAMF.R-DICKS lANATIDAH: lACHYIiRLS)

|i.u"isons lit ilic common "logger-lieail" ( 7, i uicrciis i
and llic "Lainas-back duck'" {T. piiUii linnicus).
including total length, wing length, four dimen-
sions ol the bill, wing-spread, and lengths of tarsus
and nntklle digit. He also noted interspecific dil-
ferences in bill lamellae, bill shape, wing-spurs,
coloration of primaries, sternal shape, si/e of su-
praorbital glaiul. intestinal color, si/e ot testicles,
and habitat. However, Bennett ( l'-)26:.^27) cau-
tioned that, despite these distinctions, the plumage
pattern of the Ihing species is almost identical to
that of its tlightless relative.

Phillips (IM2,S:287-2*^7). in his classic lour-
N'olume work .1 Ndtuidl Histmy aj the Dm ks. had
become much less certain of his laxonomic con-
clusions on steamer-ducks. He stated in llic lirsi
paragraph of his tiescription (p. 2S7 ). "I regaril ihc
question of two races as yet unresolved but think
we may go so far as to say that the hndings cannot
all be explained on the basis ol one natural spe-
cies." He still retained Tachycrcs ciiicrciis as the
single species in the group, but repeatedly admit-
ted in the text that more than one species might be
recogni/ed. in hisdiagnoses Phillipscompromised
by separately describing a ""gra> phase. Tcicltxcrcs
rincirits'.'" (p. 2S7) which correspondetl to the
Patagonian tlightless form discussed by Blaauw
(1916, 1917): a "red phase. Tin hxctcs puiiu hun-
iciis?" (p. 2SS) which agreed v\ith the tlying form
of Blaauw and others: and an ""intermediate t\ pe"
(p. 2SM) comprising the large, possibly tlightless
birds from the Falkland Islands, described by
Brooks ( 1917) and Phillips ( 191 7). that resembles
in plumage and soft parts the tlying birds of the
continent. He pro\isKinall\ concliKled that these
"phases" represented age-classes, which presumed
that sieamer-diicks require up to three years to
reach matiirilN'. Phillips (pp. 290-291) acknowl-
edged several problems with this treatment: (1)
there were known to exist large tlightless steamer-
ducks (on the continent) in which both sexes ha\e
yellov\ bills, the \oung of which being flightless
trom birth, but that have wings that are absolutely
(not relativel\ ) shorter than those of the smaller,
""red" tlying form: (2) some ""red-type" birds were
known to be reproductively mature, and appeared
to be lulls developed in plumage anil wing spurs:
{?< ) apparent abundanceof ll\ ing birds \ arieil inex-

plicabl\ even m the same localit\. e.g.. R. M. Beck
tinind at Chiloe Island that tlying birtis were com-
mon during May-Jinie but, during December-Feb-
ruar\. W. Percy did not see a single steamer-tluck
ll\. even when pursued: (4) in the 1-alklands it
appeared that males of the large "gray-type" mate
w ith ""red-type" females, but the young produced
from such parents were unknown. The apparent
mixing of "types" and diagnostic characters in the
Falklands seems to have been primarily respon-
sible for the reluctance of Phillips to elevate his
gra\ and red '"phases" to full species.

Pliillips ( 192.^1) was not alone in his i|uandary.
Snouckaert van Schauberg ( 1926: l."i()-l .S 1 ) re-
viewed the differing views about the genus, but
olTered no opinion of his own. Wetmore ( 1 926:4 1 S )
listed only one species. T. vincirns. but com-
mented: ""The question of specific entity among
the flying and non-llying steamer ducks is one that
IS tar from settlement." .Stresemann ( 1927:47) re-
V ievved briefly the controversy, and concluded by
quoting a letter from Phillips (dated 14 December
1926) that "...the presence of one species will not
explain the story of the steamer duck." Stenhouse
( 1929: IS."!- 1 86). in a catalog of several of the Hrst
specimens of steamer-ducks stored at the Scottish
Museum, acknowledged the taxonomic debate,
but judged that (p. 186). ""The balance of opinion,
especially among held naturalists, is in tavour of
there being two | species j."" Mogensen ( 19.^0:207),
however, adopted a weaker position, relegating
living pdiacluiiiicus to a subspecies of a single
species T. ciiiereus. in his Clwcklisi oj Buds ofrhc
World. Peters (19.i 1:176) listed only a single spe-
cies of steamer-duck. T. hviichxpicnis. but foot-
noted that the question concerning the number of
species to recognize in the genus was ""...still an
open one." Conversely, Hellmayri 19.i2:.^.^.^-.^.^7)
described both 7'. hrachyplcriis i.\rn\ T.palavhonuiis
for Chile, but sinnlarly stated (p. .^^7) that ""...the
question whether the II v ing iiuliv iduals reallv con-
stitute a different species is tar trom being settled."
Reynolds ( i9.^2:.^.'i) went further, stating: ""it is
quite incomprehensible to me thai the huge series
ot skins in the .States has not established definitely
the fact that in Tierra del Ftiego — at all events —
two species must be acknowledged." Dabbene
I U),^2) reviewed the |iublished controversy con-

10

UNIV. KANSAS MUS. NAT HIM MONOGRAPH NO. 8

ccrniiii: ilic s\sicm;itKs cil Tiiclivcrcs. including
tiic lliive "phasL's" discussed h> l^iiiiiiiis (192.'^).
and prov iiicii accoiinls I'oriwo species — tlightless
7'. cincrcKS ami IligiUed I', paluchonivus. Casares
( 19.^.^: 14(1) tallietl t\u) species olsieanier-ducl\ fur
.Argentina linciiuiing llie Falklands). j-iiii listed no
binomina or distrihulional limits.

At this late tiate. a curious, almost l.amarckian
variant ol the "adolescence' hypothesis ot
Cunningham was proposed by Chapman
( iy2fi:l2(); iy3-^:.^6l-.Vi2). a natmalist with sub-
stantial lield experience with both Hying and
flightless steamer-ducks on the coasts and moun-
tain lakes of southern Chile. Chapm.m obsersed
that flying indivitluals occurreil on the coast in
winter but evitlently not in summer, when they
were seen on inlaiul lakes, and flightless birds
occurred year-round on the sea coasts, accompa-
nied by obviously young birds in summer. He
allempted to reconcile this apparent seasonality of
tlightlessness by suggesting thai there was only
one species of steamer-tluck in which all yining
birds (until their first winter) could lly. but that
birds nesting on saltwater later became flightless,
whereas birds nesting on freshwater must travel
betvseen their nests anil coastal feeding grounds
and hence retained the power of flight throughout
life. Palmer (19.^4) also cited the 'adolescence"
hyothesis as the explanation for flighted and
flightless steamer-ducks.

h'inally Lowe( 1934:467— W.'Sj.armeil v\ithsiinl\
skins, eggs, embryos, ami tietailed field notes on
both flying and flightless steamer-ducks collectetl
by I'. W. Reynolds in Tierra ilel I-iiego. as well as
single spirit specimens of both the Hying (from
Reynolds in Tiena del Fuego) ami flightless forms
(fromW. Percy at Chiloe),csiablished bey omi doubt
the existence of both flying ('/'. pdiuchonicus) and
flightless (■/'. /jrcuiiyplcrns) species of steamer-duck
in continental .South .America. Lowe and Resnokis
ilocumentetl a number of tliffeiences: hafiital amf
locomotion; plumage pattern and soff parts; tracheal
ami s\ ringeal morphology ; egg si/e and thickness of
shells; weights, tlimcnsions, muscle weights, and
plumage pattern of well-tle\eloped embryos; and
dimensions of cranial and postcranial skeletons.
They even listetl the ihlferent names given the two
species by the local ^'ahgan and ( )iia tribes. Re\ nolds

and Lowe lackeil specimens from the lalkland Is-
lands, but Reynokls (/// Lowe 1934:470) as.serted:
"In the lalklami Islands the case, if not identical, is
similar; possibly the forms found there may require
subspecihc separation from the corresponding cat-
egories of Tierra del Liiego. I have heard this belief
expressed, and Mr. Bennett's remarks (Ibis. 1926. p.
327) do not altogether fit my Tierra del Fuego
specimens."

Lowe (1934) also specifically aiklressed the
hy|iothesis of tiev clopmental loss of flight pro-
posed by Cunningham. Based on an examination
of skeletal specimens then available, he wrote (p.
4SS-489): "...At this distance of time we may. too,
have little or no hesitation in stressing the opinion
that Cunningham hati a v cry inailequate idea of the
complexity of the |iroblem v\hich lay before him.
We may. loo, feel confulent that the birds he col-
lected with their cranial sutures still unfused were
luvenile specimens, which mav well have be-
longed to either the flying or non-flying species.
Be this as it may. however, there does not seem to
be a scrap of ev idence for Cunningluim's theory
that the fly ing Sleamer Ducks are only the Juve-
niles of the non-flying. The osteological speci-
mens collected by Mr. Rev nolds. as well as those
in the British Museum, so far as one can place
reliance on them. disprove it." With this statement.
Lowe finallv laid to rest the hvpothesis of
Cunningham, altfiough the idea remained in the
popular literature for decades (e.g., Neilson cl al.
19(10:2466).

Not surprisingly. Reynolds ( I934:3.'i()-3.'il;
l93.S:S4-S.'i) promptly employed Lowe's new tax-
onomy in hisow n works. However. Percy ( 19.34:867-
S6S). having |irov ideil Lowe wiih the important
spirit specimen of the (conlinental) flightless fonii.
was not enthusiastic about scime of Lowe's conclu-
sions. Percy (1934:867) denied having statetl any-
where (as averred by Lowe | I934:46S|) thai he was
com inced ol the v alidity of the "one-species' view,
but then went on to point out ""undoubted facts" on
steamer-ducks w hich he felt vv ere m)i considered by
Lowe( 19341. Ihese points were: ( I ) flying birds are
absent from the coast of central Chile during De-
cember-February when downy young are present:
ami (2) during May ami .lune tfie ""same flock"
contains a mixture of flving. Ilightless, ami "inter-

STEAMER-Dl CKS (ANATIDAE: IACHYI:RI:S)

iiicdialc" slcanioi-dLicks. coiilrais lo ihc claim ol
Lo\\c( l'-)34:46<S)iliatllK' tliyhllcNs hirds iiuoasial
Chile keep to themsehes.

Boiibier (1934). evidenil\ iiKlepeiuleiiilN ol
Lowe ( 1 934 ). included Tciclixcirs in a bnet re\ iew
ofavian fiightlessness. Citing ihe works otBlaaiiw
(1916). Wace (1921). and Bennett (1924. I92(i).
Boiihicr ( 1 934 ) locogni/.ed two species ofsteaniei-
diick anti notetl that the living species ( /'
ptitiii liiiiin ii\) was characterized by smaller total
length (662 mm) but longer wings (28.^ mm) than
the respective dimensions (720 mm. 270 mm) ol
the flightless species {T^ ciiicrcii^. considered to
inhabit both the continent and Falkland Islands).
BoLibier (1934) also mentioned the interspecilic
dit't'erences in bill color and patterns of secondary
remiges described by Bennett ( 1924).

Unfortunately, significant errors in taxonomy
were soon to follow the landmark work by Lowe
(19.^4). Zotta (193.^:1X0) listed both of the ta\a
recognized by Lowe ( 1934). but provided inexpli-
cably inaccurate distributions for both species.
Zotla ( 1935: reprinted in 1944) linnicd the distri-
butional range of flying T. pcilacluinuii.s to Isla
Chiloe. the Straits of Magellan. Tierra del Fuego,
Isla dc los Estados. and Santa Cruz, whereas he
included in that for flightless T. hracliyptcms a
much larger region ( Valdivia to the Straits on the
Pacific coast, the Falkland Islands, and the Argen-
tine provinces of Neuquen. Ri'o Negro. Chubut.
Santa Cruz, and Tierra del Fuego). one that postu-
lated the presence of the flightless form on inland.
Ireshv\atcr lakes. This discrepancy cannot be at-
tributed to a simple reversal of distributional de-
scription between the two taxa. in that the opposite
aiTangement wnuld exclude the Falkland Islands
from the range of the flightless species. It is likely
thai ihe erroneous distributional descriptions given
b\ Zotta (1935) contributed to the errors made
subsequently by Reed (1939) and Junge (1939).
both of whom included the land-locked .Argentine
province of Neuquen within the distributional
ranges of taxa described as flightless.

A Second Flightless Species

Eventually, a taxonomic anal\sis that encom-
passed flying and flightless steamer-ducks from

both continental and Falkland localities was con-
tributed by Murphy ( 1936:951-972) in his classic
w ork. The Oceanic Birds of South AiuericiL From
an examination of 106 skin specimens and a num-
ber of eggs and downy young. Murphy distin-
guished three species: ( I ) Falkland Flightless
Steamer Duck (Tachycics hi\u iiypwiiis), limited
to the Falklands. earlier assumed by Lowe ( 1934)
to be conspecific with the continental flightless
species; (2) Flying Steamer Duck { Tpiiuu hoiiu us).
occurring throughout southern South America and
the Falkland Islands: and (3) Magellanic Flight-
less Steamer Duck (f. ptcncrcs) of the coasts of
southern Chile. Tierra del Fuego. and Staten Is-
land. Murphy (1936:954) dismissed the name
(7/k7c;(.v (first applied to steamer-ducks by Gmelin
1 1788:506]) as unavailable for an\ of the species
of Tiichyercs because it had been applied previ-
ously to the Gadwall {Anas strepera) by Gmelin
( 1 774:249 ). a conclusion reached earlier by Collin
( 1927:54). He characterized the three species us-
ing standard skin measurements and plumage de-
scriptions, as well as detailed comparisons of
downy young, egg size, life histories, locomotor
behavior, and body proportions (especially the
ratio of tarsus length to wing length). His studies,
augmented by the field notes of R. M. Beck, also
revealed (p. 953 ) that in some respects the Falkland
Flightless Steamer-Duck more ck'sels resembled
the Flying Steamer-Duck than it did the Magel-
lanic Flightless Steamer Duck. Stoner ( 1942:17-
IS) later reported the finding of J. E. Hamilton of
the Falklands that whereas flightless T.
Ivin hxptcrns was considerably heavier than T.
ptitui lionicus. it had wings of "identicar" length.
The three-species taxonomy proposed by
Murphy ( 1936). with few exceptions (e.g.. Schmidt
1943:55: Berlioz 1950:881 ). was adopted by orni-
thologists during the next four decades (e.g..
Ilellmayr and Conover 1948:374-377: Goodall el
al. 195 1: 162-167: Delacour 19.54:296-278; Meyer
de Schauensee 1966:40: Weller 1976:45). One
taxonomic error, however, is noteworthy because
of its perpetuation by subsequent authors. In ac-
cordance with the taxonomy of the day. Hellmayr
( 1932:335) listed T. hnichypteius as the flightless
species found in coastal Chile. The taxonomic
implications of Murphy ( 1936) lor Chilean oini-

12

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

thology were ciaiiticti b\ Reed and I'lidipjil B.
( 1 938: 1 3 ). who pointed out that flightless Tachycrcs
on the Pacific coast were T. ptenercs. not T.
/7/w/n'/»/('/7(.v. Evidently unaware of Muiphyl 1936)
or Reed and Philippi B. ( 1938), probably misled
by Zotta ( 1935). and perhaps attempting to follow
Lowe (1934). three authors— Reed (1939:34-36),
Housse (1942:177. 1948:329) and Behn
(1942:121) — misclassitied the flightless birds of
Chile. T. ptenercs. as T. hrachypterus. a name
applied by Murphy (1936) to the Falkland en-
demic. Housse ( 1942:177. 1948:329) even explic-
itly listed the Falkland endemic as T. ptenercs. and
later he ( 194.5:91-92) worsened the distributional
confusion by listing all three taxa for Chile. Housse
( I94.'S:'-)1 ) explainetl that 7". hrachypterus was a
resident of the Falklands but that, although
flightless, its rapid swimming enabled it to visit
southernmost Argentina. Chile and adjacent is-
lands. Another naturalist, Barros V. (I94.^:2()();
I948:.52), repeated the error by listing T.
hrachypterus as the flightless steamer-duck of
coastal Chile. Perhaps in response to these errors.
Philippi B. ( 194.5) noted the new name applied by
Murphy (1936) to the flightless steamer-duck of
Chile.

A Foi KIH Sl'KtiKS

.Substantive ilifliculties with the taxonomicand
distributional conclusions of Murphy (1936) be-
gan to appear by the late I95()"s. Steamer-ducks
were known to occur on the Atlantic coast of
Patagonia as far north as Puerto Deseado. Santa
Cruz Province (48°S) since Burmeister( 1888:248).
Murphy ( 1936:969) gave this as the northern limit
for T patachoniciis on the Atlantic coast, evi-
dent I \ Luiaware of the s|iecimcn ot Tpaiui hcnu lis
reported by Scott and Sharpe (1912:487) farther
north in Rfo Negro Province (41"S). Much later.
Bo (1958:39) reported an adult male /
patachoniciis liikcn in Bahi'a Solano. Chubut Prin-
ince (46^S). These distributional revisions soon
were incorporated into regional avifaunal works
(Olrog 1959:71, 1963:100, I968a:lll. 1474:50:
Meyer de Schauensec 1966:40).

Observations of apparently flightless steamer-
ducks on the Atlantic coast of Patagonia also

challenged the information gi\en by Murphy
(1936:958), who stated that the continental
flightless species ( /'. ptenercs) was limited in dis-
tribution to coastal environments from Corral.
Chile to the islands of Cape Horn and Slaten
Island: an earlier description of the range of T.
ptenercs by Murphy (1936:179), however, left
some doubt as to the possible infrequent occur-
rence of the species in coastal Santa Cru/. Argen-
tina. It is clear from the route taken by R. M. Beck
(Murphy 1 936: 182), the exceptionally industrious
collector working for Murphy, that Beck made no
collections of birds in coastal Chubut. Without
presenting supportive specimens or sight records.
Olrog (19.59:70. 1963:100) described the Atlantic
distribution of 7'. ptenercs as seacoasts from Tierra
del Fuego to Chubut. He (1968a: 1 1 1 ) later limited
the Atlantic breeding distribution ol 7. ptenercs to
Tierra del Fuego. but slated thai the species ranged
farther north during winter. In three of his later
works. Olrog (1959:70. 1463:100. 1968a:lll)
described the Falkland Flightless Steamer-Duck
('/'. hi aclnptcrus) as limiied entirel\ lo ihe
Falklands. One decade later. howe\er. Olrog
( 1474:50) extended the range of T. hrachypterus
"cNentualmente" to the coast of Chubut. while
maintaining the \ iew that T ptenercs also occurs
on the coasts of Santa Cru/ anil Chubut. In his last
work. Olrog ( 1984:269) continueti to mclude the
Atlantic coast of Santa Cru/ and Chubut (to Ciolfo
San .lose) within the distributional range of 7".
ptenercs. Meyerde Schauensec (1966:40; 1470:33)
also included the pro\ inces of Chubut and Santa
Cru/ w ilhin the distributional limits of 7, ptenercs.
The ulea thai /, ptenercs seasonally extended its
tlistribiuional range northward along the .Argen-
tine coast was amplihed b\ a distributional map in
.lohnsgard (1478:137). which depicteil a winter
range for this species encompassing the coasts of
Santa Cru/ and Chubut (to Peninsula Valdes).

The diagnostic characters gi\en by Murphy
(1436). based almost entireh on museum skin
specimens. v\ere of little hel|i in tield identitication
of sieamer-ducks on saltwater, ami dillicullies in
idenliticationof specimens continued. A skin (held
at .American Museum) of a male steamei-diick.
collected on the coast ol Cluibui in 1886 b\ .1.
Vouiie. was labeled as A/, cincrciis and later as /'.

STEAMER-DLICKS (ANATIDAE: TACHYERES)

piciicnw. iirobabl\ on tlic basis cil ihc localitv and
its moderately large size: the skin w as ciitL-rcd into
the catalog of the American Museum in pencil as
"piciicrcs'?". Apparently, this specimen was a\ ail-
able lor study (perhaps cataloged) by R. C. Murphy,
but was never mentioned in a publication and
evidently was overlooked by all subsequent inves-
tigators. On 7 November 1460. P. S. Humphrey
collected a leniale steamer-duck (skin specimen at
F'eabody Museum. Yale University ion Isla Blanca.
near Camarones. Chubut. which he identified by
k>cality as T. paiaclidimiis. Three skiii specimens
col Iccted by C. Kovacs — a male from Piinta Tombo
(Chubut) on 19 April 1968 and a male and female
from Camarones on 10 July 1970 — were origi-
nally idenlihed as 7. prcncrcs and arc held at the
Museum of Natural Science. Louisiana State Uni-
versity. C. Kovacs also collected and prepared as
skins two male steamer-ducks (now at the Museo
Argentino de Ciencias Naturales. Buenos Aires).
collected on 16 November 1971 and 5 February
1972 in the Bahi'a de Camarones. Chubut: these
were identihed as T. pataclhuucus. In November
197 1 . M. Gochfeld collected a male steamer-duck
found dead on the beach at Punta Tombo which
was prepared as a skeleton and identified as /
ptcncri's (now at .^merican Museum of Natural
History. New York). On 10 June 1972. C. Kovacs
collected another pair of steamer-ducks at
Camarones. Chubut. which were donated as
mounted specimens to the Museo Argentino: the
specimens remained uncatalogued and unidenti-
fied until 1989. On 25 August 1972. J. R. Jehl. Jr.
collected one male and one female steamer-duck
in Bahia Concepcion. Chubut: the male was pre-
pared as a study skin and the female as a skeleton
( both deposited at the San Diego Museum of Natu-
ral llistor\ ) and both initially were labeled as T.
piciicrc.s. then re-identified as 7". patiichnniciis.

Boswall and Prytherch (I972:l2.-i) found
steamer-ducks nesting at Punta Tombo. Chubut.
which they initially identified as T. ptcncrcs be-
cause of the apparent fiightlessness of the birds.
Later the\ were persuaded by Olrog (based on
presumed breeding ranges) and J. Delacour and P.
Scott (from their examination of a photograph of
three birds i that the species involved was 7'.
puicK liiiiiuits. Boswall and his colleagues only

savs a biril "'tl\ ' once in live da\s of observation,
and this was a very short, weak, downhill passage
of a female from nest to water. Evident
fiightlessness of the birds was attributed lo wing-
molt, which seemed to be indicated in the photo-
graphed birds (p. 78). a condition confirmed later
by M. \V. Weller and O. S. Pettingill (Boswall
1 973a:35). Boswall (197.^a:35) stated that the wing
length of a drake found dead also supported the
identification. Boswall (I973a:33) and Boswall
and Maclver ( 1979:75) also reported the measure-
ments and weights of six eggs from a nest at Punta
Tombo. which were larger than measurements for
[\ pahuhiiniciis presented b\ Murphy (1936:969)
and agreed most closely with those for T.
hruclnpienis. Boswall and Maclver (1979:75)
speculated that the small means given by Murphy
( 1 936 ) for T. palachimicus may have resulted from
misidentifications of large 7'. /'(//(/( In in mis eggs as
those of 7\ hrachyplcnis. Similarly. Daciuk
( 1976:27-29. 1977:363) identified by locality the
steamer-ducks nesting on Isla Quintano. Golfo
San Jorge, Chubut as 7'. patch hoiiicus. despite the
apparent fiightlessness of the birds and their un-
usually large eggs.

Todd ( 1979:160) reported the suspicion of M.
Rumboll. an Argentine ornithologist, that flightless
steamer-ducks on the Atlantic coast of Argentina
were either T. hvacbyptcnis. or an undescribed
species or subspecies. Rumboll and F. Erize per-
suaded P. S. Humphrey and M. C. Thompson to
collect specimens of the steamer-ducks in coastal
Chubut during an expedition to Patagonia in 1979.
Based on these specimens, collected from Puerto
Melo (Chubut). Puerto Deseado (Santa Cruz), and
Llshuaia(Tierradel Fuegoi.as well as skins exam-
ined in Argentine museums. Humphrey and Thomp-
son ( 1980) provisionally recognized (but did not
formally describe) four new species of steamer-
tluck: ""white-headed steamer duck. "" flightless, of
coastal Chubut: "'masked steamer duck." also
flightless and from coastal Chubut: "lesser Hying
steamer duck" of southern coastal Patagonia: and
■"pygmy flying steamer duck." based on a single
skin specimen froni Lago San Martin ( Santa Cruz I.
Additional specimens collected by Humphrey and
B. C. Livezey in marine and freshwater localities
during the next two years permitted a formal de-

14

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

sLTipticni ot llic VVhiiL'-licadctl l-'lightlcss .Slcaincr-
Duck (7. leucoccpliulus: Humphrey and Thomp-
son 1981). Upon .sub.sequent examination, the
specimen.s collected earlier in Cluibut by Young,
Humphrey, Kovacs, Gochfeld. and Jehl also proved
to be /'. leucoccphalus. Humphrey, howe\cr. did
not describe the other three putati\e laxa. The
"masked" torm was found to be a collection of
small individuals ol' T. leucocephalus in alternate
plumage. A larger sample of flying steamer ducks
revealed that the "lesser" form was an artificial
collection of small specimens from the osteologi-
cally variable and geographically differentiated T.
patachoniciis (Humphrey and Livezey iy82a,
Livezey 1986b). The single specimen of the
"pygmy" form was determined to be a juvenile of
freshwater-nesting T. piitiicluuiii us.

OVKRVIF.W

Throughout the taxonomic history of steamer-
ducks, there were repealed, protracted, and often
imaginative attempts to reconcile contemporary
view s with new. distinctly contradictory informa-
tion. There also w as a stubborn reluctance to admit
the existence of two closely related sympatric

species of duck that appeared to ditfer |irmcipally
in the ability to fly. Indeed, ornithologists for
several decades preferred the improbable notion
advanced by Cunningham that flight in steamer-
ducks was a function of immaturity, a conclusion
based on a small, unfortunate sample in which the
flightless species (7". piciicrcs) was represented by
adult specimens and the flying species by incom-
pletely ossified juveniles or subadults. The tax-
onomy proposed by Murphy (19.^6) had a pro-
loimd influence on subsequent workers who en-
deavored to make their observations and interpre-
tations conform to his scheme. Taxonomic progress
undoubtedly was impeded also by the overall simi-
larity in size and appearance of the species, a
problem exacerbated by the occurrence of three
molts and plumages per annual cycle in some or all
of the species ofTcicliycrcs (Humphrey and Live/ey
i982a). Difficulties of collecting and preparing
specimens of these heavy, toughly built, and diffi-
cult-to-kill birds, as well as the remote distribu-
tional range of the genus, further limited the num-
bers of specimens available for siiid\.

Remarkably, the history of the taxonomic con-
sensus for Tachyeres mirrors a current phyloge-
netic hspothesis for the genus (Fig, 2: Livezey

Separate genus recognized
by Lesson (1828).

Tachyeres

Flying and flightless species
distinguished by King (1831)

Continental and Falklond flightless

potachonicus

pteneres

— brachypterus

species distinguished by Murphy (1936).

Two continental flightless species distinguished

by Humphrey and Thompson (1981).

^- leucocephalus

Fig. 2. Phylogenelic tree for Tachyeres. based on Live/.ey ( 19S6r) and Corbin ci uL ( l')SX). aiul aiuiolnlidii of
the chronological coincidence of key diagnoses of species by taxonomists.

STEAMER-DUCKS (ANATIDAE: TACHYEKES)

15

I^Sdc. C\)rhiii (7 cil. l'-)XS). The (irmlhological
ciiinnuinilN tirst recogni/ed ;i single laxon (Tepie-
sentinu" the aneestiir ot tlie geiuisi. and hiler dis-
tinguished the tlighted lineage from the eollectiv e
flightless (minxMed h\ the tirst branehing in the
tree). Next. Magellanic T picncics v\as distin-
guished taxdiioniically ticini Falkland T.
hidihyptci IIS. which corresponds to the second
In pothesi/ed vicariance event and associated spe-
ciation. Finally, the recent recognition of /'.
lciU(Kcplhilii\ parallels the last glaciation-related
vicariance event presumed to have isolated /
Iciicoccpluihis of Chubut from its sister-species 7.
hi iiclixplcnis. This congruence of taxononiic his-
tory with phslogeny is particLilarl\ mUessorthy
because of the poor correspoiKlence. inferred ear-
lier bs Miirph\ ( 1 436). betueen similarity of pkim-
age aspect and ph\logenetic relationship.

Variation in flying ability in Tlu Incirs has pre-
occupied most taxonomists. and the impact ol

lliyhilessness on the classitication ol the genus
has been profound. Ironically, m light of current
know ledge, ability to fly is at best an unreliable,
composite character that is difticult to iletermine
aiul is the result ot a lumiber of anatomical,
behavioral, and environmental conditions. Pereyra
( I^.SO; 146) was one of tlie last authorities to
recogni/e but a single species of Eik Incic.s al-
though he (1943:227) listed two species in an
earlier work: he explained the variation in flying
abilit\ 111 the genus as strictly the result of sexual
ditferences in body weight, the massive males
being flightless but the lighter females being
capable of low flight. It is known now that an
appreciable proportion of male Flying Steamer-
Ducks (T. pafciiiii'iiiciis) at some marine locali-
ties are permanently flightless (HLnnphre\ and
Live/ey l'-)S2b). Such locomotion-independent
determinations, however, required systematic
methods that were not available until recentlv.

SYSTEMATIC REVIEW

Rklationships of Tachyeres

Of all the ornithologists recogni/mg more than
one species of steamer-duck, only Dabbene ( 1 402 )
dill not consider them congeneric: the assignment
of flightless steamer-ducks to Tachyeres and the
flighted speciesto.W/c/v'/Vt'/zr,', by Dabbenet 1402),
however, may have resulted as much from the
taxononiic confusion that reigned at the turn of the
century as from a perception of relationships.
Most other systematists placed all steamer-ducks
together in their own genus: the older name
Mu iiipivnis Lesson, IX2X. being preoccupied in
Pisces, was replaced by Tachyeres Owen. IS75.
although the former was used infrequently into the
twentieth century.

Exceptions to this separate-genus treatment
includeil assignments of steamer-ducks to the gen-
eralized Linnaean laxa Aiiser (lor 'geese') and
Alias doi" 'thicks') by early taxononiists (e.g.,
Gmelm I7SS. Latham 1790). Another view of the
generic relalit)nships of steamer-ducks was iiuli-
caled by several nineteenth-century ornithologists
who included the steamer-ducks in already recog-
ni/ed eenera of di\ iul! ducks: Ouleniia (currenth

included in Mclaiiilia. scoters: King 1S2S).
Fiili'^^iilii (currentiN A\ih\a. pochards: Schlegel
IK66), and Caiiipu>laiiuiis (currently Caiiiptu-
iliYiniiiis. Labrador Duck: Gray IS7I ).

The perception of a relationship between
Taihxcres and largely northern-hemisphere div-
ing ducks was shared by a nuniber of other taxono-
mists who. although they assigned the steamer-
ducks to their own genus, indicated this view by
their subfamilial classitications. These higher-level
afliliations with diving ducks involveil sea-ducks
i.Piilxsiicta.Somateria.Melaiutta.m^ABiicephala)
and pochards ( Aythy ini ). and were inferred prima-
rily on the basis of shared diving habits and di\'-
ing-related anatomical characters (e.g.. Scott and
Sharpe 19 12: Peters 1931: Delacour 1936;
E^oellicher 1939. 1942: Hellmayr and Conover
194S: Verheyen 1953a. b. 1955. 1961: Simonetta
1963: Markham 1971). This 'alliance" between
largely northern-hemisphere genera of di\ing duck
and the austral steamer-ducks iiecessaril\ influ-
enced early biogeographic sur\e\s of waterfowl
(e.g., Sclater and Salvin IS76. Sclater ISSOa.
Sclaterand Hudson I8S9, Casares 1940).

16

UNIV. KANSAS MUS. NAT. HISI'. MONOGRAPH NO. S

On iho basis ol iho bclun ior. e Menial nioipliol-
ogy. and syriiigcal anatomy ol stcanicr-dLicks.
Delacour and Mayr (1945) concluded that the
reseiiiblance ol Tuchxcirs to the eiders was super-
licial and that steaniei-ducks were most closely
related to the shelducks (their Tribe Tadorninii.
This treatment was followed by most taxonomic
discussions involving Tiuliycnw dining the next
three decades, but most authorities chose to em-
phasize the distinctiveness of the genus by placing
it in a sepaiale tribe allied with the shelducks
(Boetticher 1952: Delacour IM54: Gilliard 1M5S;
Moynihan 1958; Johnsgard 1960. 1961a. b. |9ft.^i.
1965. I96,S. l97S;Lack 1974; Brush 1976; Winkler
and Walters I9S,^; Kolbe 19841.

An osteological study of \\aterfov\l led
Woolfenilen ( 1961 ) to recommend that /(/iV/vcrcs
be moved from the Tadornini to the dabbling
ducks, tribe Anatini. Previously suggested by
Ripley ( 1957). this 'aflinity" between the dabbling
ducks and Tacliycrcs did not prove influential for
subsequent writers in that none adopted this clas-
sification. Several writers, however, subsequently
retreated from a tirm assignment of Tacliycrcs to
the Tadornini. either listing the genus between the
shelducks anti the liabbling ducks (Meyer tie
Schauensee 1966. 1970; Blake 1977; Johnsgard
1979) or stating that the intrafamilial relationships
oi'Tachycrcs were unclear ( .Austin 1 96 1 ; Delacour
1964. Weller 1976). One series of investigations
did provide some equivocal phenetie support for
the "altinity' between Taclncrcs and the dabbling
ducks; biochemical comparisons of uropygial se-
cretions by Jacob (1977. I9S0. 19S2) and Jacob
andZiswiler( I9S2) revealed similarities between
those of steamer-ducks anti those oi Anus and the
eiders (Soinalcrid).

A phylogenetic analysis of Recent genera of
walertbwl based on morphological characters con-
hrmed the inclusion of Tinlncrcs within the
Tadorninae (l,i\e/ey 1986a). with a less well sup
ported hypothesis of close relationship between
Tacliycrcs and two other 'aberrant" genera — the
neotropical Torreiil Duck {Mcriiaiiciin urnuiui)
and the New Zealand Blue Duck (IImiiciioIciiiiiiis
iiialacorlnncluis). The corresponding classilica
lion of TacliYcics — subtribe Merganetleae of
the tribe radoiiiini in the aiuilul snhlamily

ladorninae — is followed here. Relationships
v\ithin the genus Tacliycrcs were inferred using
morphological (Livezey l986c)andelecirophoretic
tiata (Corbin c! ai. 1988). These studies indicated
that the comparatively primitive but variable T.
iniiaclioniciis is the sister-species to the three
llightless species, and. of the latter, the medium-
si/eii .Atlantic species (/'. Icucoccphalns and T.
hracliyptcriis) are closest relatives.

Sibley and Monroe (1990:.^2) considered the
three llightless species as constituting a
superspecies. but incorrectly considered piciicrcs
to be the senior includetl specitic taxon. More
surprising was the inclusion of Tacliycrcs in an
enlargetl Tribe Anserini. an eclectic group com-
prising the true geese, sheldgeese and shelducks.
and the 'perching ducks' (Sibley and Monroe
1990); no empirical support for this arrangement
was cited.

Synonymies for Ta( idiri-s

Members of the genus Tacliycrcs ha\e been
given 25 different binomial (and trinomial) names
(excludingapparent misspellings) involving seven
genera. Most of the oldest taxa were ambiguous
with respect to the four currently recognized spe-
cies. Many provided no distinguishing characters
or described broad distributional ranges, and are
presumed to have referred to the entire known
genus. Others provided localities of observation,
which in some cases exclude certain llightless
species from further consideration on distribu-
tional grounds, but the information given does not
permit a confident identitication of species. The
tieieiniination of whether the birds were T.
jhiiaclidiiiciis or members of a llightless species
presents particular difficulties, and is often impos-
sible for birds described from coastal habitats (see
discussion of identification beyond). For example,
the numerous early accounts of birds seen on
saltwater in the f-alkland Islands (e.g.. Lesson
1826. Darwin I8.i9a, b) described birds of large
size and apparently incapable of llight. I'nforlu-
nalelv for purposes of identification, both charac-
teristics can apply to both T paiacht>iiiciis and T.
hnichypicriis. and the species are virtually inilis-
lint!uishable in the field.

STEAMER DliC'KS (ANATIDAI:: lACHYERES)

17

Llntoniinatcl\. lor dL-cadcs rulliiwiiiu ihc dc-
\^:\■\\■)U^motl . pulcH limiu u\b\ Kinu( IS.il. 1X3*-').
most writers iikrIc no mention ol a second species
of steamer-dnck (e.g.. Darwin iS34a, b). Lesson
(1S37. IS.iS) was one ot the lirsi to accept the
existence ot a second species of Tiniiycics. but
interpreted the discovery to mean that the large
flightless species was loiind in the F-alkkuuls (which
lie had visited) and the smaller /'. ihiuiclinnlcus
was found in the Straits of Magellan. The tax-
onomy of Eyton ( IS.^S. 1869a) presents a special
problem, in v\hich he recognized luo species —
hrachxpicnis and palaclionictis — hut slated that
both species v\erc Hightless and he provided sus-
piciously similar measinements for the two forms.
Most 19th-century iirmthologists. however, fol-
lowed their prominent British colleagues — nota-
bly Sclater. Cunnmgham. and Owen — in treating
Tcichxcrcs as monoiypic. During this period, pro-
ponents of the one-species \ iev\ varied in the
distributional limits applied to steamer-ducks: e.g..
through the IS7()s. Sclater and his co-workers
listed only collections and reconls of steamer-
ducks from the l-alklanil Islands, but subsequenth
extended the distributional limits of the genus to
the continent. Salvadori (1X95:373) wfote that
steamer-ducks were '"Confined to Straits of
Magellan and Falklands."' Reed ( 1939) was one of
the last authors to recogni/e but two species of
steamer-duck — Tacliycrcs hrarlnplcnis and T.
pcikicluiiiicus — and was alone in listing both for
the inland, moimtainous Argentine province of
Neuquen! Similarls. Junge( 1939) included moun-
tain lakes among the habitats of the single taxon he
recognized for southern Chile. T. pauu luniuus. a
species he described as flightless. Both aiuhorities
may have been misled by the inexplicably inaccu-
rate species disii ibutions given by Zotta
(1935:1X0).

Consequently, we list midcr the generic ac-
coimi the lollou mg classes of references: ( 1 ) ref-
erences which explicitly or are presLuiied to in-
clude the entire genus Tacliycrcs imder a single
taxon: (2 1 references to apparently tlightless
steamer-ducks, generally with locality informa-
tion, but with descriptions inadequate for excki-
sion of /, piikniiii/iiciis: aiul (3) references to
steamer-ducks, presumed flightless or otherwise.

Ill which the ilistributional limits given include the
ranges of two or more species of flightless
Tacliycrcs. For these nonspecific citations we in-
clude a single-letter designation (in brackets) to
iiulicate the geographic region concerned, thereby
defining the subset of species that ina\ have been
included. These designations are:

G general: referred to entire genus (often con-
sidered to be monotypic ). or the region poorly
delined or included entire distributional range
of genus.

F Falkland Islands: T. hiiicliypicrus and/or T.
pataclwniciis involved.

T Tierra del Fuego (including Isia de los
Estados); 7'. ptcncrcs and/or T. patachoiiicus
involved.

A Atlantic coast of Patagonia (coastal Argentina
north of Tierra del Fuego): involved T.
paUii htiiiicus and/or possibly T.
Iciicoccplialiis.

P Pacific coast of Patagonia (Chi lean coast north
of Tierra del Fuego): involved 7. /'?(7;c;c.s and/
or 7. palachoniciis.

Sources clearly referring to flightless forms but
as distinct only from the flying form (i.e., there
was no diagnostic or distributional information by
which to determine which flightless form was
intended), are included under the flightless species
included in the distributional ranges described
(annotated as "in part"). References to cmrently
recognized species (based on examination of listed
specimens, descriptions, illustrations, observations
of birds in flight or on inland lakes, inability to fly
in captivity, and/or distributional information) are
listed under the corresponding current ta\a.

Pages listed include all references to the taxon
in the works. Apparent misspellings also are in-
cluded (indicated by asterisks), as are errors in
gender, if the erroneous taxa were used consis-
tently m the works. Other taxonomic complica-
tions are annotated following the individual cita-
tions. Etymology of species names was describeil
by Ciotch (1981 ). Published vernacular names are
listed by language and are followed by the earliest
references to each name. Suprageneric classifica-
tion follows Livezes ( 1986a).

18

L:N1V. KANSAS MlIS. NAT. HIST. MONOGRAPH NO. 8

Oicici' .AnsciiloiniCN (Waglcr. 1S31 )

Suborder Anseres Wagler. 1831

Family Analidae Vigors. 1825

Subraniiiy Tadt)riiinac Reichenhach, 18.^2

Tribe Tadornini Delacour and Mayr, 1945

Sublrihe Mergaiiclteae Bonaparte. 1853

Genus Taciiyeres Owen, 1875
Steamer-Di ( KS

■n)i,wu-ilca (7;;/.«7/.v/.v.— Molina (1782:239) |P|;
considered synonymous with "Microptcnis
cincrciis Gray" by Philippi ( 1867:793) but not
by Deautier and Steullet (1930:474).

Alias cliicrcu. — Gmelin ( 1788:506 |F.T|); Garnol
(1826:59 I F|): Brelim ( 183 1:903 |G|): Menem
( 1 841 :29 |G| ): Giebel ( 1 872:347 |G|): Frauscher
(1 894a: 174 iT|).

,4/((V.v hnwhyplcni. — Latham ( 1 790:834 | F| ); Qut)y
and Gaimard (1824:347 |G1): Garnot (1826:59
|F|): Reichenbach (I836:entry 394 |G|): Dar-
win (1839a:257 [F]: 18.Wb:l90 |F1).

Aiisvr cincrciis. — Bonnaterre (1790:112 |F|).

Auscr hrachypiciiis.—W'icUUn (1818:344 |F|):
Dumeril (1825:470 |G|).

Alias hrai Inplcra el i incrca. — Lesson ( 1826:227-
228|G|: I831:630|F|: I837:533|F|: 1838:720
|F|).

Micniplcrus hiiichxpicnis. — Lesson ( 1828:416
|F|. gender of species not gi\en): Gould
(1841:136 |F|): Lichtenstein (1854:100 |P|):
Wood ( 1 862:735 |G1): Hubbard ( 1907:2 1 7 |(i |).

Xficriipicnis (incrca. — Reichenbach (1845:t. 77.
illus. 894 |G|).

Microptcnis cincrcns. — G. R. Gra\' ( 1840:74 |G|;
1844:623 |G|i: .1. E. Gray (1844:140 |G|):
StrickIand(1841:39|G|):Hartlaub(l846:l9|Fl):
Des Murs (1847:457 |P.T|); Reichenbach (1852:
plate VIII. table VII |G|):Boeck( 1 855:5 II |P|):
Bonaparte (1856:651 |G|): Gemiain (1860:315
|P|): .Sclaier( 1860:389 \l-\: 1867:335. .MO |P1):
Pelzein ( 1 865: 1 39 [P| ): Cunningham ( I S68: 1 27
|F.T|: I87lc:262 |F.T1: Giglioli\ 1868:498 |T|):
Philippi (1867:793 |P|: 1868:283. 309 |P|):
.Sclater and Salvint 1868: 189 |T|: 1873: 130 |T|):
Thomson ( 1 877:205 | F.Tl ): Vinciguerra ( 1 883:58
|T|): Lalaslc( 1893:122 |T|); Paesslert 1909:103
IF.T.Pj).

*|/\/;(;,s| piciicros. — Attributed erroneously to
Forster (1844:338) by Bonaparte (1856:651).
.Salvadori (1895:374). Scott and Sharpe
(1912:489). and Phillips (1925:288).

Fnlii-nla cinerea. — Schlegel (1866:13. 118 |F|;
1872:274 1G|): Sundevall (1872:149 |G|).

Cainpiolainiiis |subgenus indeterminate!
(7/UT('/(.s.— Gray (1871:88 |G|).

Tacliycrcs hracliypicrns. — Owen ( 1875:254. 258.
266. 272 |G1: 1879:366 |G|): Collin (1927:54
|G|): Peters (193 1:76 |G|): Pereyra (1950:196
IT.F.PI).

I'achycrcs cincrcns. — Sclater and Sal\ in ( I 876:402
|G|; 1878:437 |T|): Sclater (l879b:3U) IT]:
1 88 1 : 1 50 |T| ): Sharpe ( 1 89 1 :309 | Fj: 1 899b:224
|G|): Reichenow ( I882a:48 |G|: 1 882b: 1 7 |G|):
Coppinger (1883:56. 61-62 |T|): Stejneger
(1885:149 |G|): MacFarlane (1887:202 |F.fl):
Burmeisier( 1888:248 I A|): Ridgway ( 1889: 138
|T|): Sclater and Hudson (1889:137 |F.T|):
Tristram (1889:47 |T|): Lucas (I89I:I.W |T1):
James (1892:10 |P|): Gadow (1893:154 |T|:
1902:169 |G|): Newton (1894:518 |F.T|:
1895:597 |F.T|: 1896:737 |F.T|: 1899:518. 597
IF.Tj): .Salvadori (1895:326. 373 |G|; 1900:633
IGj); Lane (1897:195 |P|): Beddard (1898:456.
460. 466. 468 |G|): Martens (1900:25 |G1):
Dabbenet l9l4:296|G|):()ates( I9()2:I84|F.T|):
Nicoll (1904:49 |r|); Vallentin (1904:33 [F|):
Hubbard (1907:217 |G|: Reed (1907:105 |P|):
Wilton cl al. (1908:6. 62 |F|): Fvans ( 1909:121
|G|): Knosvlton and Ridgway (1909:195 |G|);
Townscnd (1909:242 IT]; |9|():6 [T]): Cobb
( 1 9 1 0:66 1 1- 1; 1 933:80 1 1- 1 ): guijada-B. ( 1 9 10:339
|G|); Mitchell (191 1 :5l4|G|):Paessler( 191 1: 128
|T|: 1913:41.43.48 1T|: 1914:272 |T|; 1915:60
|T|): Brabourne and Chubb (191 2:57 |T.F| ): Scott
and Shaipe (1912:487. 489-492. 498 1 G | ): Bertoni
(1913:76 |G|): Shuleldt (1913:210-215. 217-
220 |G|): Brooks (1917:155 |F|); Brooks in
Phillips (1^17:117-118 IF. T]); Aiion>moiis
(1918:205 |F|); Finn (1924:138 |G|): Lynch
Arribal/aga (1924:270 iA.T|): Chapman
( 1926: l20|P|):Heinroih(l929:532|G|): Palmer
(li}34;4()y6 |G|); Schmidt (1943:55 |G1):
Hamilton (1946: 1 31 1 1- 1 ); Glegg ( 1947:433 |F|):
Meunicr (1959:453 |G|); Neilson cl al.
(1960:2466 |Cr|).

STEAMER-DUCKS i ANATIDAE: I AC //) 7 /^7 S)

19

.\/(.s(7- ( iiicrcii. — Milne-Edwards ( ISS2:4n |Ci|)-
AiiiisiMn nipicnis)ciiici-ciis. — FrauxclK-r( lSM4b:

205 |T|1.
Tachycrcs cincrca. — Beddard (1897:467 |G|):

Boker(1935::()2 |C,|).
'^Trachycii's (//k'/CH.v.— Vallenlin { U)()| :35() |F|).
Tachycrcs hruchxpicra- — Peters (1931:176 |("i|):

Boetlieher (1939:434 |G|); Berlicv ( 19.S():,SS1

Ki|): Simnneita ( 1963:127 |Ci|).

Vernacular Names

Race-horse. — Byron (1773:?()); Hawkesworih
(1773:411); Cook (1777:186): Forster
(1777:492): Buffon (1798:159: 1812:369).

Loggerhead. — Penrose (1775:35): Claylon
(1776:104).

Loggerhead goose. — Penrose (1775:35); Latham
(1785:439).

Loggerhead duck. — Forster ( 1777:493).

Steamer-duck. — King ( 1839:35).

Sea-horse.— Blaauw (1916:448).

Spiinish

Ouethu.— Molina ( 1782:239).
Quetu.— Des Muis (1847:457).
Cagues.— Des Murs (1847:457).
Quetru. — Germam ( 1860:315).
Oueira.— Giebel (1872:347).
Palo quetru. — James ( 1892: 10).
Quelar.— Lane (1897:195).
Quaitar.— Lane (1897:195).
Palo vapor.— Blaauw (1912:67).
Quetri).— Phillips (1925:287).
Quettio. — Chapman ( 1933:361 ).
Pato vapor grande no volador. — Pereyra
(1950:196).

Duhh
Stoomboot-eend.

-Schle^el (1872:274).

■Reichcnbach ( I836:entry 394).
R i e s e n e n t e . — R e i c h e n o w

(jcyi)ian
Kur/llugelente.
P a I a g o n i s c h
(1882a:48).
Dampt'ergans. — Frauscher ( 1894a: 174).
r)uetra der Patagonier. — Fiauscher ( 1894a: I 74 1

tiraueii Tauchente.— Cobb ( 1910:20-21 ).
DamplschiHente. — Agosiini ( 1924: 114).

I- rciicli

Oye grise. — Pernety ( 1769:576).

Oye du plein. — Pernety ( 1769:576).

Canard-lourdaut. — Cook ( 1 778:285 ).

Canard au\ ailes courtes. — Quoy ami Gamiard

( 1824:139).
(Jie du plain. — Lessi)n ( 1826:228).
Canard-loiudaud. — Lesson ( 1826:228).
Canard a ailes courtes. — Reichenbach ( I836:en-

try 394).
Canard micropiere. — Oustalet ( I891:B2I2).
Canard (a) vapeur. — Oustalet ( I891:B2I2).
Canard cendre.— Cobb ( 1910:20-2 I ).
Canard geant. — Boubier ( 1934:85).
Macreuse australe. — Housse (1942:329).
Canard plongeur de Patagonie. — Berlioz

(1950:881).

Ihllhin

Pato a vapor. — Agostmi ( 1924:1 14).
Aniira a vapore. — Agostini ( 1955:74).

C:c( lii>sli>]\d

Kachyne.— Kolbe (1984:170).

Russian
y iKii - nopoxoa. — Kolbe ( 1984: 170).

Japanese

.— Yamashina (1986:70)

Fiiciiian: (tribe not given)
Karawiis-poug. — Coppinger ( 1883:122).

Content

Tiuhycrcs comprises totu species, one com-
paratnelx widespread, geographicallv variable,
and (largely) (lighted species, and three mutually
allopatric. marine-coastal, flightless species: Fly-
ing Steamer-Duckt /./)<//</( 7/()/;/(7f.v). tirsi described
by King ( 1 83 1 ) and decisively diagnosed by Lowe
(1934); Falkland Flightless Steamer-Duck (T
hrinii\picri(s). segregated Irom the continental
flightless species by Murph\ ( 1936); Magellanic

20

UNIV. KANSAS MllS. NAT. HIST. MONOCiRAI'H NO. 8

Flighlies.s Stcamcr-Duck (/./uc/k'/cv). aconipara-
tively distinct species tiiat was liie lirsl to be
distinguished from tlie Hying Ibrni. and toiniaily
diagnosed by Murphy (U>.^6); and While-headed
Flightless Steamer-Duck (7. Icucdtcpluilus). an
overlooked or misidcntitied endemic ot coastal
Chubut, Argentina, described by Humphrey and
Thompson (1981).

TviM-: Spf-Cies

The type species of the genus Tacliycrcs is. by
monotypy. Anas hruchypicra Latham 1790. i.e..
the species name was that to which Owen ( 1S7.^)
reterred in naming the genus Tachycrcs. A neotype
for I. hnitliypicnis is designated below. Fortu-
nately, this species (as currently delimited) is rep-
resentative of the genus for several reasons: {\)T.
hrachypicriis shares all the diagnostic characters
of the genus: (2) the species is flightless (a distinc-
tive character rare among the Anatidae btit shared
by T. ptcncrcs. '['. Icmoccphalus. and some males
of T. pauiclioniciis). of moderate size, and its
plumage pattern is very similar to those of its
congeners (with the possible exception of the
unique 1. picucrcs): {?>] T. hnichxptcnis is the
species mosi frcquenlK kept in captivitv: and (4)
this species was of historical importance, and ref-
erences to this form occur in the writings of most
early explorers and naturalists (e.g.. Lesson IS.^ 1 :
Darwin IS.VJa. b: Ciould 1S4I: Sclaler lS61a).

BkII I Dl S( kllMION

Steamer-ducks are metlium to large Fuego-
l^atagonian marine-lilloral (all species) and Iresh-
ualer (one species) thicks, are predominantly
battleship gray with lov\er breast, belly, and most
secondaries white, sluiw variable pattern anti col-
oration of the head, and have moderately elongate,
recurved central reclrices. Members of the genus
lack any metallic coloration anil are sexually di-
chromatic in some definitive plumages. Males are
larger and more robust (bull -necketl ) than females.
Bills of adult males are largely bright orange.
Except in juveniles and subailulls. the leet are
bright yellow-orange.

DisrRiBirioN

Members ot the genus are limited in distribu-
tion to marine coasts and (in 7. palachoiucus)
freshwater, primarily mountain lakes, throughout
southern .Argentina. Chile, and in the Falkland
Islands (Fig. 3). The northern limit of the conti-
nental range of the genus can be approximated by
a line connecting Concepciiin. Chile vi> ith Viedma,
Argentina. The marine-litioral range of the flighted
species o\erlaps. at least seasonalh. those of each
of the three, mutually allopatric llightless species.

Tachyeres patachomcvs (Kinc;, 1831 )
Fi.viNc Steamf.r-Di ( K

Micropicriis pataihonuiis. — King ( 1 S3 1:15;
1 S3y:.S42); Lesson ( 1837:533: l838:720):Eyton
(1838:143: 1 869a: 100-101 ): Abbott
(1861:162): Sclater (186lb:46): Giglioli
( 1 875:934 ): Oustalet ( 1 89 1 : 2 1 2-2 1 6. 2 1 8. 220-
222. 224-226. 227-23 1 . plate 5. in part): Sclater
(1892:173-174); Dabbene (1902:403-404).

■''MicniptcilDliispiitcuiuiiiit litis. — Eyton ( 1 838:50;
1869b: plate 18. reprinting of tigure from 1838
work with misspelling).

Micropicriis puruchnnica. — Eston ( 1856:348).

Micropicriis ciiicrcus. — Cox (1863:235. m part):
Sclater and Salvin (1870:499): Cunningham
(I871a:493. in part); Paessler (1909:103. in
part).

{Micropicriis niucroptenis. — Giglioli ( 1875:934).
parenthetical suggestion of alternate name.l

Micropicriis Inncliyptcriis. — Moreno ( I879:| 165.
173|).

'''Micropicriis hriuiiiplcriis. — Bove ( 1883:13).

'Micropicriis paliaclioniciis. — Vinciguerra
(1883:58).

"■Micropicriis pcihr^oniciis. — Carbajal ( 1 900:282 ).

Tiicliycrcs ciiicrciis. — Sclater (1881:1 07. in part );
Sharpe ( 1 88 1 : 1 3. in part ): Craw sha\ ( 1 907: 1 1 0,
in part): Nicoll ( 1908:163. in part); Skottsberg
( 1 9 1 1 :47 ); Scott and Sharpe (191 2:487. in part);
Phillips ( 1 925: 1 34. 287-288. in pari ); Weimore
(1926:418).

Tuclixcrcs puiiiclioiiiciis. — llolmherg ( 1895:
|22l|): Dabbene (1910:233: 1932:205-206);
.Sclater (1913:315); Blaauw (1916:488-489,

STEAMER-DUCKS (ANATIDAE: TACHYERES)

21

-40°

'5° W

-35° S

Concepcio

Puert

<I I . Chilo

UJ

o
o

-45°

P Taita

<

Q.

— 50°

T. ptenere

-55°

Fig. 3. Approximate dislrihutuiiial liinils ot the lour spcLics (.liTiniixi-j cs. Range of/', paUn liciui ks (excluding
vagrants) is enclosed b> diagonal barruig (meludes coastal arul uiland areas), and the coastal ranges ol the three
(mutually allopatric) tlighlless species are shown in stipple.

97

UNIV. KANSAS MKS. NAT. IlISI MONOCRAPIl NO. X

441; 1417:274-276; 1421:5S): Mogcnscn
(1417:85): Anonymous (1420:77): Bcnncll
(1924:280-282: 1926:327); Vallenlin (1924:
325): Snouckaert van Schauberg (1926:150-
151 ): Sirescmanii ( 1927:47): Helhnayr ( 1932;
336-337): Boubier (1934:85-86): Lowe
(1934:449-482.484-487.489^93: 1935:4261:
Reynolds (1934:351): Re\nolds /;/ Lowe
(1934:470-472.477-179); Reynokls( 1935:85):
Zotta (1935: 180; 1944:30): Bullock ( 1936: 137);
Murphy (1936:199. 208. 953-956. 958. 964-
965,968-969): Steulleland Deautier( 1936:.Vi4.
366-367); Junge (1939: 1 66. in part): Laubiiiann
(1940:18-20): Morrison (1940:254): llousse
(1942:177: 1945:92: 1948:329); Stonor
(1942:17-18): Pereyra (1943:227): Trimble
( 1943:420); Delacour and Mayr ( 1945: 15. 38;
1949:42, 63): Parques Nacional Argentina
(1947:39); Hellmayr and Conover (1948:374-
377); Olrog (1948:473: 1950:518: 1959:70;
1963:100: 1968a:l 1 1: 1968b:plate 11; 1979:50;
1984:92. 269); Yane/ (1948:154: 1949:8-10):
Ripley (1950:5; 1957:225); Goodall ci al.
(1951:162-163): Boettieher (1952:23. 68-69,
91); Pergolani de Costa (1953:36: 1970:35):
Verheyen (1953a:384. 410. 434-435:
I953b:463. 486-487: 1955:2.15): Delacour
( 1954:271. 276-277; 1964:335): Philippi-B. ci
al. (1954:29); Scott (1954:61: 1972:48);
Agostim ( 1955:74): Holgersen( 1957:59);Tour
(1957:162); Bo (1958:39); Moynihan
(1958:183. 200-201): Van Tyne and Berger
(1959:234); Cawkell <■/ al. (1960:216); (). .S.
Petlmgill (1960:606); .Sclionwelter( I960: 1 3 1 );
Cawkell and Hamilton (1961:15): Johnsgard
(1961b:64: 14(,2:14(); 1965:94; 1968:105:
1978:135; 1979:453): Berndt and Meise
(1962:192): Godoy (1963:31): Philippi-B.
(1964:46): Bernalh (1965:98); Caik|iiisi
(1965:232): .lohnson (1965:195-196; 1969:5:
1970:2): McKinne\ (1965:195): Peltingill
(1965:71): .Smith (1465:56); .lohansen
(1966:231): Meyer de .Schauensee (1966:40:
1970:33; 1982:33): StresemannandSiresemann
(1966:305): /apata (1467:364): Lack
(1968:347); Weller (1468:200: 1469:128;
1472:26.37: I975a:295: 1975b:87: 197.5c:ll();
1976:45: 1980:26); llumphre> <7,//, ( 1470:129-

130. 135-139); MarkhanK 1970:46: 1971:48);
Sibley and Ahlquist (1972:93): Strange
(1972a:256); Bock (1973:208): Boswall
( 1973b:248); Duguy (1973:6: possibly included
/; leiKoceplialiis): Jehl ( 1973: 129); Jehl ct al.
( 1 973:6 1 . may have included 7'. leiicocephaliis):
Vigil ( 1473:69-70): Jory ('?(//.( 1974: 132): Lack
(1974:85): MacLean (1974:193); Merne
(1974:34. 78): Schlatter (1974:2: 1976a: 14:
I976b:137. 140; 1979:163): Morony ci al.
( 1975:2 1): Woods (1975: 123:1 982:50): Gruson
(1976:11); Jehl and Rumboll (1976:146);
Kiihnemann ( 1 976: 157); Vcnegas C. ( 1 976: 1 77-
178. 183): Wolters( 1976:98): Blake( 1977:227):
Daciuk ( 1 977:363. 37 1 ; probably included in T.
Icucocephalits): Jacob (1977:52. 54-58:
1 982:87 ):Navas( 1 977:35,86): Reed (1977:27):
Navas and Bo (1977:79): Clements ( 1978:27):
De la Peiia (1978:57: 1986:79; 1987:39);
Soothill and Whitehead {1978:280-281):
Blandamer and Burton (1979:132): Goodall
(1979:76): Todd (1979: 160): Hillgarth and Kear
( 1979: 142): Venegas C. and Jory H. (1979:73):
Conlreras ct al. (1980:45): Howard and Moore
(1980:71: 1984:71): Erize ct al. (1981:131.
178. 194): Goich (1481:83): Humphrey and
Thompson ( 1 48 1 : 1 . 3. 5-6, 8): Storer ( 1 48 1 :53;
1484:637): Venegas C, (1981:217: 1986:11.
61); Araya (1982:5): Humphrey and Livezey
(1982a:l-2. 10. 12. 15.21-22: I982b:368.370.
371: 1485:444-451); Jacob and Ziswili
(1982:274. 276): Live/ey and Humphrey
(1982:12-16; 1983:485-486; 1984a:257:
1984b:368-376: 1985:154-156: 1986:540-553.
556): Scherer and Hilsberg (1482:.360, 373);
Corhm (1483:216): Carpi (1484:116): Daciuk
and Heber(1984:174):Kolbe( 1984:170, 172);
Walters ( 1984: 1 8): Edwards (1985:2 1 ): FjeldsS
(1985:111): Harrison (1985:665); Live/ey ct
al. (1985:18-19: 1986:445-450): Murray
(1985:567): Narosky ct al. (1985:11):
Nuechiorlcm.ind Storer ( I985a:87; 1985a:568):
Raikow (1985:82. 86-87); Araya M. ct al.
(1986: 116): Clark ( 1986: lOO); Live/ey
(I986b:51 1-512. 515-523; I486c:458. 460-
466. 467: 1484a:l. 3. 6-15. 17. 20-26. 28-28,
31_33. 40: 1989b: 1 8 1-1 82: I989c:428;
1490:661): McGowan (1986:306; 1484:538,

STEAMF.R-I)l CKS lANATlDAE: TACflYERFS)

23

.•S4:); VaniashiiuK U'XfrTO); Duiiiiiiii: ( l'-)S7:23):
lliimpliiex (7 (//, ( IMS7:6<S-6M); Naiosks and
Fianioni {I9S7:I6): Narosky anil ^■/Ln■ieta
(mS7:7i));Wolsey(19S7:3y):Cabal(l^)XS:25);
Craulhicr ( 1 '■)S.S: 113); Madge and Bum ( 1 4SS;,SS.
1 SO): Ryan crul. ( 1988:29. 32. 33 ): Bniiion and
NiiCLlitcrlcin (1989:18): FJelds;i and Krahbc
(19^)0:120. 712. 718): .Sibley and Monroe
( 1990:32).

Tinli\cic.\ ciiivrviis var. \Tcicliycivs pauulKni-
;(7rs|.— Waee (1921:201).

raclivcrc.s ciiwrciis pauu lionu us. — Mogensen
(1930:207).

ruclwcrcsiuacnipicnis. — Anon_\nioLis( 1933:230):
evidently based on informal suggestion of al-
ternate name Micmptcrus nuicropienis by
Giglioli (187.^:934).

Tachycics hrachypicnis. — Zotta ( 1 93.'i: 1 80. in part
|?|): Pereyra (1950:196. in part); Gollan
(19.S 1:286).

*Tacliycrcs paiir^oiiiciis. — Reed ( 1939:34): Behn
(1942:121); Pisano V. (1973:33); Daciuk
(197.^:172).

*Tcnliyrcs piiiathoiin us . — Krieg ( 1940:161:
19.S 1:1.^9).

*Ttnh\crtis ptiiiu iinnicus. — Zapata ( 1969:23).

*Tachycrcspataclu)imlnis. — Raikow ( 1970:. 570).

'■'Tacltycrcs pard'^hnnicus. — Barros ( 1 97 1 : 1 72 ).

'■^Tacli\ cries pahu hnnii us. — Adams and
Templeton (1979:39).

'■■TlachycrcsJ pahichomicHS. — McGowan ( 1982:
21.5).

Tavhycirs ptcncics. — De la Peria ( 1987:40).

Vkrnacular Names

Eii\ilish

Patagonian niicropleiLis. — Eyton ( 1838:143).

Flying loggerhead. — Abbott ( 1861:162).

Lesser .Steamer Diiek.— Blaauw ( 1912a:54).

Canvas-baek(ed) (duek).— Bennett (1924:280).

Lake logger. — Bennett ( 1924:281 ).

Flying Steamer-Duek.— Bennett (1926:327).

Flying loggerhead duek. — Bridges ( 1948:64).

.S7)(//;/.\//

Pato silvon. — Bove (1883:13).

Pato leal.— Revnolds ;;; Lowe (1934:470).

Pato \ apor que \ uela. — Bulloek ( 1936: 1 37).

Pato quetru volador. — Housse ( 1945:92).

Pato vapor volador. — Delaeour and Mayr

(1949:63).
Pato vapor grande volador. — Pergolani de Costa

(1953:36).
Pala vapor gran volador. — Za|iala ( 19(i9:23).
Pato vapor de agua duke.— Vigil ( 1973:69).
Pato volador. — Kuhnemann ( 1976: 157).
Pato azul. — Kuhnemann (1976: 157).

Cicnuan

Fliegende Dampfsehiffente. — .iohansen ( 1966:23 1 ).
Langflugel-Dampfsehiffente. — Beiiidt and Meise
(1962:192). Wolters (1976:98).

FiCIH I)

Mieroptere de la Patagonie. — Lesson ( 1837:533;

1838:720).
Canard-vapeur volant. — Johnsgard ( 1978:135).

Czcihoshnak

Kaehyne patagonska. — Kolbe ( 1984:172).

Russtari

nararoHCKaH yxKH-napoxoan . — Kolbe ( 1 984:
172).

.Icipanese

Y |v^^ j,-^ . — Yaniashina (1986:70).

Fuci;ian (Yahi^an)
Tachka.— Phillips (1925:288).
Dusea.— Reynolds in Lowe ( 1934:47 1 ).
Tushea.— Bridges (1948:435).

F-^uci^iiiii [Oiui)

Tari.— Reynolds ;// Lowe ( 1934:471 ).

Original Dt-:scRipri()N and Tvpf.

First distinguished from regionally sympatrie
tlighiless eongener(s) by King ( 1S31 ); an earlier
applieation of the speeies name lo T. picucics. in
the binomen Oidcniia paiiU hoiiicti King. 1828.
has been suppressed by the international Commis-
sion of Zoological Nomenclature ( 1 99 1 ) antl placed
on the Official Index of Rejected anil linalid Spc-

24

UNIV. KANSAS MUS. NAT. HIST. MONOCiRAI'H NO. 8

cific Names in Anilogy (Livezey IMSMbi. The
original description by King (1831:1?) included
the reddish throat and scapulars and compara-
tively small si/e of the species: King ( 1X3^:542)
later included the capacit\ I'or flight among iis
diagnostic characters. Substantial geographic varia-
tion exists in T. ixilaclioiiicus. and the species may
best be considered a superspecies (Humphrey and
Livezey 1982a. b: Livezey 1986b. c).

No type material o'iT.pahichonicus is knov\ n to
be extant. Accordingly, we designate as neotype
the follov\ing skin specimen, held at the Sub-
department olOrnithology. British Museum (Natu-
ral History). Tring. Hertfordshire. England:

Specimen no. I928-4-2I-I — Male: collected on
Estancia Viamonte. Isla Grande. Tierra del Fuego.
Argentina; on 1 September 1 927: by P. W. Reynolds.

Standard Mhashrements
(mean ± stantlard deviation, range. //)

Toial wcialii (g).— Males: 29.S8 ± 296. 2100-
.3600. 54. Females: 2347 ± 295. 1665-31 IS. 51.

Mhs; Icii'^ihiMX. mm).— Males: 304± 1 1 . 282-
325. 62. Females: 287 ± 10. 265-312. 64.

Ciilmrn lcn;^!h (mm). — Males: 53.9 ± 2.6. 48-
60. 67. Females: 52.3 ± 2.3. 47-58. 67.

Nail width (mm).— Males: 11.6 ± 0.9. 10-14.
66. Females: 10.8 + 0.8. 9-12. 67.

Tarsus Icn^lli (mm ).— Males 60.0 ± 3.0. 53-66.
65. Females: 56.3 ± 3.1. 50-66. 67.

Tail lcn;^tli (arc. mm). — Males: 111 ±6. 93-
119. 31. Females: 104 + 6.91-117. 30.

Mi:asiiki;mi-.nis (m\0 oi- Ec.cs (v = 40)

Leiii^lh. — mean = 77.1. range 73-84.
Width. — mean = 52.2. range 51-55.

Bkii I l)i s( kii'iioN

This species is the smallest of the steamer-
ducks, but the mean length ol wing (arc) is greater.
sex for sex. than in the three larger, flightless
species. Body is predominaiiil\ battleship gra\ in
aspect with considerable chcsinul on scapulais,
sides, and tlanks: lower breast, belly, and most
secondaries are white (l-'ig. 4). Recurved central

tail feathers are longer, bill proportionately longer
.inii more delicate in prolile. anil the bods and neck
are more slender than in the flightless species.
Males are larger and more robust than females.
Bill color of adult males is bright yellow -orange,
duller during the prebasic molt; bill is darker in
adult females and subadults and juveniles of both
sexes.

The species (at least Atlantic-coastal popula-
tions) is characterized by three molts and plum-
ages per cycle, the prebasic moll replacing the
whole feather coat, the other molts replacing only
the feathers of the head and neck. The detinitive
alternate and supplemental plumages are sexually
(.lichromatic.

.luvenal and basic plumages: head ami neck
(both sexes) are dark brown with a faint whitish
|iostocular streak in the Juvenal plumage.

Dehnitive alternate plumage: male — gray
crown, brown cheek, white postocuhir streak; fe-
male— head and neck dark brow n w itii interrupted
postocular streak.

Detiniti\ e supplemeni;il plumage: male — head
and neck white (crt)wn pale gra\ in some individu-
als) with small patch of chestnut on throat; fe-
male— head and neck medium brown with short
whitish postocular streak.

CTass-l downy differs from tlownicsof all otiier
Taclncics in having \er\ narrow, continuous
supraloral and supraocular patches which are sepa-
rated from (not continuous with) the postocular
streak.

DisiKiiu HON

FUing Steamer-Ducks occur throughout the
distributional range of the genus (Fig. 5). Murphy
(1936) was overly conservative in his delimitation
of the inland, freshwater distribution of this spe-
cies, as were .lohnsgard (1978:134). Kolbe
(1984:171). and Madge and Burn (1988:58). T.
parachoniciis breeds on many freshwater lakes (in
low densities) from Isla Grande north to Lago
Nahuel lliiapi. Neuquen. Argentina; the species is
also known to breed on Isla de los Estados. Tierra
del Fuego (P. Angle, pers. comm.) and on islands
111 the Beagle Channel (llumphrev ci <// 1970).
Oliog (1984:269) inexplicably extended the dis-
tributional range ot'T. ixitachoniciis on the coast of

STEAMER-DUCKS (ANAIIDAE: TACHYERLS)

25

M »- ' . ■

Fig. 4. Photographs ot ihc tour species ot Tavliycics in the held: A T. leucocephaliis. male (left) and female
(right), by R. Straneck (PunlaTombo. Chubul. Argentina. October 1977); B — T. ptcncirs. male (front) and female
(rear), by D. Zimmerman (I'shuaia.Tierra del Fuego. Argentina. December 1983): C — 7' hiu( livplcni.',. male (left)
and female (right), by B. C. Live/ey (Port Stanley. Falkland Islands. January 1984): D — I . /hiun liaiiii /(s. male, by
G. L. Nuechterlein (Laguna Nevada. Santa Cruz. Argentina. January 1982).

26

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

-40

55°-

-55°S

Fig. .>. IX-l;iilcd m;ip o\ the distribution of /, puhuiuiniciis based on speeiniens. published reeords. and
atlequately doeurneiited, unpublished observations. Speeiniens are shown as sohd eireles. sight leeorils as open
eireles; evidenee ol breedins; (nests, broods) is indieateil b\ diai;onal slashes.

Cliilc north to the \teinit_\ of .Satiltaiiii (3.V'S): or the l'io\ itiec of Nuble ( Araya M. c/ <;/. 10S6).

this species occurs at least inlrec|uciill\ as far (ioodall (7 1//. ( IM.'S 1 : 16.M ga\c its nortiierti limits

tiorth as 39"S in CTiilc (M. Christie, utipiiblished in Chile as Bahia dc Talcahuaiio on the coast ami

inventory tor Parqtics Nacionalcs dc .Arueiitina) Niihlc mlami. I-jcklsa ami Kiabbe (I')4(1:I2())

STEAMER-DUCKS (ANATIDAE; TACHYHRES) 27

dcsL-nlxHl / inihnhoiiicus as: "('omnioii at 700- T \CHYERES BRACHYP I liKl S (LaTHAM, 1790)

1200 111 (111 hanvn upland plateaus ol iiilaiul Sla F.M.Kl.AM) FlJCHTLKSS StEAMKR-DicK
Cru/ and on the Sonuineuia plateau ol' Rio Neuro.

Arg.. and in Nubie aseends to I SOO in.'" The Amis IvachxpieriL — l.athani ( 1 740:S34; listed ni

northeinniost Atlanlie specimen ol /, iniituli- generic syiion\m\. iiia\ ha\e incliided T.

onlciis Ironi Rio Negro Prinince. Argentina (Scott pauu honii tis).

and Sharpe 1M()4). and sight records troiii Bahia Mu lopicnis Ivdt Inptcrus. — E;_Nton (lS.vS:144. in

San Bias. Buenos Aires Pro\iiice(M. Nines. |icrs, pail; IS(i4a:101. in parti.

comiii.). and Cosia Bonita. Buenos Aires Pro\ - '■ Mu lophi us hi in iixuiits. — Eyion (!S.^d:.i4S. in

ince (Narosky ci al. \'-)'ts>. Narosky and Fiameni part).

!'-)S7) probabK pertain to casual, nonbreeding Muinpiciiis viiicrcus. — Gould ( I S.SM:96); Abbott

vagrants. (ISO 1: 150. 161 ); Sclater( lS(ila:367; 1868:529;

Although inland records of Flying Steamer- 1872:256; 1877:337); Cunningham (1 87 la:493.

Ducks are most Irequentlx maile on high-altilude in part).

lakes, the species also has been reported on low - Tm lixcics cinereiis. — Sclater l 1 879a:376:

altitude lakes in Santa Cru/. Argentina and in 1880b:529: 188 1:107. m part; 1882:792;

riverine habitats near Lago Viedma. Santa Cru/. 1883:442; 1896:450): Holmberg (1895:|22l |.

Argentina, it is believed widely that / ^ P;""'; Dabbene (1902:403-404, in part);

pannlionuus on the Falklands breeds onlv on Ramsay ( 191 5:21 1 ); Wace ( 1921 :201 ): Bennett

freshwater lakes (Weller 1972, 1976), and that (1^^24:280-282: 1^)26:327. in part): Vallentin

the species is uncommon throughout the archi- < 1^24:322): Phillips (1925:134, 287-288, in

pelauo (Strange 1972b:2()6). It is likely that birds P'""- Snouckaert van Schauberg (1926:150-

breedino on fi^shwater. both on the continent and '-^l- "^ P^"''*- Selh-Smith (1927:245): Smyth

,, c iTi 1 , , r ,1 (1927:12): Stresemann (1927:47, in part);

the Falklands, nunc lo marine coasts lor tlic '

r. 11,1 wi^i i-7;> . . r Boubier ( 1 934:85-86, in part )

winter. RcNUolds (//) Lowe 19.i4:47.^) wrote ol /. , ^

putucliiiiiiiiis in Isla Grande, Tierra del Fuego:
"Tn winter it is restricted to the coast, where in

Micniplcntspaiachdiuciis. — Oustalet ( 18M1 :2 12-
216.218. 220-222. 224-226, 227-23 I , plate 5,

, I- 1 ,■ 111 P'li"-

summer man\ breed; but others penetrate tar -r , , , , ,,>^, n,, i.,.,

' Taclixcrcs hiiU hxpicnis. — Lowe ( l'^)-i4:479-4S8,

inland, spreadiiiL' wherever there is water from ,,,,. ,,,., . ., r> ii • i ,i(iii i-i,\

' - 490-493, in part ):Revnolds(// Lowe ( 1 934:470-

the sea to the mountains." However, Finn

( 1924:139), who recogni/ed but a single species

472. 474-177, m part); Zotta (1935:180, in
pan: P)44:30. in pari); MiirpliN ( 1936:194.208,

of Tcninercs. wrote: "...In Tierra del Fuego they 4xV956. 958, 961-962, 964-965, 968-969);

Isteamer-ducksl are found on fresh water also, Steullet and Deautier ( 1936:365-367, in part);

and when this Iree/es in winter, often die m ^^.^.^^ (1939:34-35, in part); Laubmann

trying to tiiul other quarters." This remark may ( |i)4(); \t))-^ Boetticher ( 1942:42: 1952:23, 68,

stem from the statement of Crawshay ( 1907: 1 14- i,| ,. Sionor ( 1942: 1 7-1 8): Delacour and Mayr

115): "[-requently I found these birds Istcamer- (1445:15. 38: 1949:42. 63): Hellmayr and

ducksl lying dead inland, starved to death appar- Conover (1948:374-376); Goodall cl al.

ently. through the free/ing of their waters." In (1951:162): Anonymous (1952:49); Sladen

contrast, but without dociimentar\ evidence or ( 1 '■)52:222 ); Pergolani de Costa (1953:36;

references, SoothiU and Whitehead (1978:280) 1970:35): Delacour ( 1954:273, 276): Moynihan

stated that the species: ■•In winter, tlies less often (1958:183); Olrog (1959:70: 1963:100;

and can be found resting or sleeping on fro/en I968a:110: I968b:plate 11: 1979:50; 1984:92,

inland waters, but m Isla Grande (Tierra del 269); Van Tyne and Berger (1959:233-234;

Fuego) it is restricted to the coast during winter 1976:397): Cawkell ct al. (1960:217); E. R.

months." ^ Peltiiigill(l9(,():145):O.S.Peltingill( 1960:606:

28 UNIV. KANSAS MUS. NAT. HIST. MONfXiRAPII NO. 8

UXi.^i:?!: 19S2:')2()); Schoinvcltei- ( lM6():l.^li: 7(/(7mTc.s7)/(7/r;<'v—ll()Lisse (194.^:91: m48:.^2M).

C'avvkell ami llamillon (1961:1.^, 1.^); Beriuil *T<niiyci('.\ hiachyptcins. — AnoiiMiKuis (19.'>l:

and Meisc (I962;1M2): Johnsgarii (1^62:l.^l; 34).

1 965:9,^: 1 96S: 1 05: 1 97S: 1 .38: 1 979:452 ): ^Tachycirs hrainlixpicra.—KcnLktixh [ 1952: 187);

PiiiK-c Philip (1962:54): (iodoy (196.^:31): Coll ( 1953a:4!4: 1953b:651).

Carlquisi (1965:231-233. in part): McKiniicy '■■'rachycre.s hracliyapicnis. — Gruson (1976:11).

(1965:212): Smith (1965:55): Johaiisen ■■'Tacliycrtcs hnnhyplcrus. — Adams and

( 1966:23 1 ): Meyer de Schauensee ( 1966:40): Templeton (1979:38).

Siresemannand Stresemann ( 1966:305): Gewalt Tachxcirspaiachoniviis. — WitienhergerandTilson

(1968:188-189): Griswold (1968:32): (1980:211).

Johnstone (1968:127): Lack (1968:347): *Tarhycrc\ hruchyllcrus. —Prowuc (1983:19:

Schmiilt (1969:125): Raikou (1970:570: ii-)s4:453).

1985:82): Woods (1970:18-19. 1975:118: */(,r/nr(TC,v /.;■,/< 7/v/)/<'n(.v.— McGowan (1982:

1980:49): Weller(1971:l()8: 1972:26,44. plate 215).

1: 1975a:295: 1975c:110: 1976:45): Scott

(1972:48): Strange (I972a:256): Bock

(1973:208): L.aek ( 1974:85): Merne (1974:34. Vern,\cll..\k N.amf.s

80): Daciuk (1975:172: 1976:27): Morony er

al. ( 1975: 12): Welly ( 1975:239. 458: 1982:282. ^-",i,'/'.v/'

543): Brush (1976:482): Wolters (1976:98): Logger-head.— Bennett (1924:280-282).

Jacob (1977:52): Navas (1977:35-36): Navas

Sea logaer. — Bennett ( 1924:281

and Bo (1977:79): Clements (1978:28): De la Logger (duck).— Bennett ( 1926:327).

Pena (1978:58: 1986:81): Kear (1978:61): Falkland Flightless Steamer Duck.-Murphy

Soothill and Whitehead ( 1978:281 ):Blandamer (1936:9.i4).

in . , 1.1-7(1 T :!Tv u II IN/11 Falkland Steamer Duck. — Clements ( 1978:28).

and Burlon ( 1979:132): Bosvvall and Maclver

( 1979:75-76): Todd ( 1979: 160. 162): Howard

andMoore(l98():7 1: 1984:71 ):Tonni( 1980: II. V""""'/'

,,, , ,,,,.,> ,w> ,-• 1 ,,>u, uT Remero vek)/. eortas alas. — Housse ( 1 94.1:91 ).

I4i: Warham (1980:98): Gotch (198 1:82): , , .. , ■ r. , . »,

,, , , ,,,, ,,,„, , , , ,„, Palo vapor de Malvinas. — Deiacour and Mayr

Humnhrev and I hompson (1981:1. .1-6. 19): ,,.,;,-,

" (1949:63).

Ilumphre\ and Live/e\ (l982a:l-2. 21-22'. ,, , , »» 1 ■ r> i ■ 1 <-■ .

' ■ • Palo vaiior de Lis Mahmas. — Peraolam de C osta

1982b:368. 371: I98.'^:944-9.M ); Mlikovsky ,u)sV^6

(1982:728): Carpi (1984:116): Live/ev and ,, " ' '" '', . ., ,^ , ,,,,,, ...

' - Pato-vapor inahniero. — MacDonaulH 1941 :45).

Humphrey (1 982: 1 2: 1983:485-486: 1 984a: 257-

259: I984b:368. 375-376: 1985:154-156: ,.

I986:.54(). .S49. 551-556): .Seherer and Hilsherg M,tteklamprsch,riente.-Berndt and Meise

(1 982:360): Daciuk and lleber( 1 984:1 74 cKolbe (ii)6"'-|92)

(1984:66. 170-172): Mendall ,7 ,_,/,( I984:,^06): ,.,iKhuul-Damplsch,llente.-Bock (1973:208):

Wolters ( 1976:98).

Walters ( 1 984: 1 8 ): Etiwards ( 1 985:2 1 ): Harrison

(1985:655): Nuechterlein and Slorer ( 1985:87):

Livezey ( 19K6b:5 1 2: I986c:458. 460-463. 465: /-,■,,,„■/,

1989a: I -3.. 5-7. 9- 1 6. 20-22. 24-28. 3 1-33. 40: Canard aux ailes courtes.-Lesson (1837:533:

1989b: 1 82): Live/ey (■/«/. (1 986:44.5-448.450): 1838:720).

McGowan (1986:305, 306): Yamashina Canard-vapeur des lies lalkland.— Johnsgard

(1986:70): Narosky and ^/uneia (1987:79): (1978:138).

Cabal (1988:24): Gauthier (1988:113): Madge

and Burn (1988:58.183): Ryan ci al. ( 1988:29): Czcvlu>sl,n<,k

Siblev anti Monroe (1990:32). Kachvne kr:ilkokokiidla.— Kolbe ( 1984:171).

STEAMER-DLICKS (ANATIDAE: IMIDhRES)

t>ojiKJieHacKasi yTKii-iiapoxoa — KolixM 1^84;

171).

Japuiuwc
y-^-i]'^ ^Yamashin;i ( 14X6:70).

Okkiinal Di;,s(kii'IK)\ and Tvpf.

This species, and ihe MagellaiiiL- /, piciicics
(below), were collectively dit'terentiaied trom the
smaller, flighted Tpcnaclioiiiiiisby luinieroLis w ork-
ers since King (1831 ). Although nian\ ol the early
accounts ot steamer-ducks were based on obser\ a-
tions of apparently flightless birds in the Falkland
Islands (e.g.. Lesson 1826. Darwin 183'-)b). com-
paratively tew authorities included specimens from
the Falklanil Islands in their comparisims: excep-
tions included Abbott ( 1861 ). Bennett ( 1M24. 1926).
and Phillips ( 1425. in part). The original description
by Latham ( 1790:834) included as diagnostic char-
acters of the species its orange bill, gray body, short
wings, white wing patches, and large size (between
that of a goose and a swan). In his 1790 work.
Latham gave the range of the species as the Falkland
Islands, whereas in his earlier work he ( 1785:439)
included Staten Island (Isia de los Estados). This
species was diagnosed as specihcally distinct from
continental flightless steamer-ducks by Murphy
(1936).

No types were designated and no t\ pe material
is known. Accordingly, we designate as neotype
the following skin specimen, held at the American
Museum of Natural History. New >'ork:

Specimen no. 443786 — Male: collected at Port
Stanley. Fast Falkland Islands; on 27 October
1915: by R. H. Beck.

Si AsmRM Mi.Ast KiiMf-NTS or Adi its
(mean + standard deviation, range. /;)

T.iUil wvr^ht (g).— Males: 4228 ± 443. 3300-
4800. 12. Females: 3519 ± 336. 2900-1196. II.

H//;,','/c/(,t;r/M arc. mm).— Males: 276+13.238-
296. 24. Females: 268 ± 12. 245-292. 15.

Ciilnicn Icniitli (mm). — Males: 56.8 ± 2.2. 53-
61. 25. Females: 57.2 ± 2.1. 5.3-60. 15.

/Vt/// U7(///; (mm).— Males: 13.5 ±0.8. 11-15.
25. Females: 12.5 ±0.8. 1 1-14. 15.

Tarsus Inr^lh (mm). — Males: 67.8 ±3.1. 60-
72. 25. Females: 63.8 ± 2.5. 58-67. 15.

Tail Icir^ih (arc. mm).— Males: 102 ± 5. 92-
1 10. 15. Females: 96 ± 7. 76-103. 12.

MlASliRKMtiNTS (MM) Ol- EgCIS (,V =11)

Lcn;^ih. — mean = 81.8. range 77-86.
Width. — mean = 56.6. range 56-57.

Briei- Di sckipiion

The body is predominantly battleship gray in
aspect with considerable chestnut on scapulars,
sides, anil flanks: lower breast, belly, and most
secondaries are white (Fig. 4). Central tail feathers
are elongate and recurved. Males are larger and
more robust than females. Bill color of adult males
is bright yellow-orange: bill is largely orange in
adult females, and darker in subadults and juve-
niles of both sexes.

There are three molls and plumages per cycle.
the prebasic molt replacing the whole feather coat,
the other molts replacing only the feathers of the
head and neck. The deflnitive alternate plumage is
sexually dichromatic: the deflnitive supplemental
plimiage is also probably sexually dichromatic.

Juvenal and basic plumages: head and neck
(both sexes) tlark brown with a faint whitish
postocular streak in the juvenal plumage.

Deflnitive alternate plumage: male — gray
crown, brown cheek, white postocular streak: fe-
male— head and neck dark brown with white
postocular streak.

Deflnitive supplemental plumage: male — head
and neck w hite (crown pale gray in some mdi\ idu-
als) with small patch of chestnut on throat; fe-
male— imknown.

Class-I tlow ny differs from di)w nies ot all other
Tcichycrcs in having the postocular streak undi-
vided and the supraloral and supraocular patches
narmw and continuous with the posiocular streak.

DisrKimrioN

Endemic to and abundant throughout the
Falklanil Islands on marine coasts and nearby
ponds: unfortunately, available records prov ide an
inadequate representation of the disiiibulion and

30

UNIV. KANSAS MUS. NAT. HISI . MONOGRAPH NO. 8

breeding range ol llic species dig. 6). Tlie pres-
ence of 7". hrachypicnis on tiie .lason Islands is
likely but unconfirmed, bul tiie s|5ecies evidently
does not inhabit Beauchene Island. Cawkell and
Hamilton (1961:13) reported that individual birds
have been observed three miles from shore.

TaCHYEKES PTENERES (FoRSTER, 1844)
M ACELLANIC FeKJHTLESS StEAMER-1)| ( K

Oidcntiapiiiiichonicii. — King{ IS2S: 100); synony-
mi/ed with Microptenis hrachyp/cnis {cunvnt\y
segregated as T. pteneres) by King (1839:35.
542). Strickland ( 1 841 :39), Gibson ( 1 877: 1 36).
and Stenhouse (1929:185; 1930:274). Kuroda
( 1 942:4 1 ) mistakenly stated that Gibson (1877)
synonymi/.ed Oidcmia patachonica King uith
Anas crislala Gmelin. As detailed by Herman <■/
al. (1990:13). Oidcmia patachouica was sup-
pressed and placed on the Official Index of
Rejected and Invalid Specific Names in Zool-
ogy via Livezey ( 1 989b) and International Com-
mission on Zoological Nomenclature (1991 ).

*Mivnipivnis hrachyplcro. — King ( 1831: 15).

Mivnipicnis liravliypUTiis. — liylon ( 1838: 144. in
pan: 1869a: 101. in part); King (1839:542).

Anas picncrcs. — Forster (1844:338).

Micnipicriis cinercits. — Cox (1863:235. in part);
Newton ( 1 870:504); Cunningham ( 1 87 1 a:493.
in part); Giglioli ( 1 875:93.3-943.963); Oustalet
(1891:212-216. 220-222. 224-226. 228-231.
plate 4); Sclater (1892:173-174); Carbajal
(1900:282); Agostini (1955:216).

Tachycirs cincreiis. — Sclater ( 1881:107. m part);
Sharpe (1881:13. in part): Holmberg
( 1 895:|22 1 1. in part ); Schalow ( 1 898:672-673 r
Dabbene (1902:403-404. in part; 1910:233)
Crawshay ( 1907: 1 10. in part): Nicoll ( 1908: 163
in part); Blaauw ( 19l2a:47-48: 19l2b:7
I M 16:488-492. plate XIV: 1917:275-276
1921:57-58): Sclater (1913:315); Mogen.sen
(1917:85; 19.30:207); Anonymous (1920:77);
Phillips (1925:134. 287-288. in part); Bennett
( 1926:327. in part); Snouckaert \on Schauberg
(l926:l50-15l.inpart):Slresemann(l927:47.
in part): Stenhouse (1929:185; 1930:274);
Dabbene ( 1932:205-206); Reynolds ( 1932:35);
Boubier ( 1934:85-86. in part).

-52

Fig. 6. DclailcxI map of the disiribulioii of 7'. hiai hypicnis based on specimens, published records, and
adequalcly documeiUetl. unpiibJisJK-d obscrvallons. Specimens arc shown as solid circles, sight records as open
circles, and evidence ot breedim: (nests, broods) is indicaleil b\ iliaiional slashes.

STEAMER-DUCKS (ANATIDAE: TACHYERES)

31

liulixcrcs h}\u hxptcrus^ — Hcllma>r ( 1432:335.
337): Lowe (1434:474-4X8. 440-443. in part;
143.5.424): RL-ynolds ( 1434:3.50-351: 1935:S4):
Reynolds in Lowe ( 1434:470-472. 474-477. in
part);Caslellanos( 1435:36): SieulletandDeauiier
( 1 435:36.5-367. in pail ): Zolta ( 1 435: 1 SO. in part;
H)44:30. in part): Junge (1434:161. :n part);
Reed (1434:34-35. in part); Belin (1442:121):
Housse (1442:177; 1448:324); Pereyra
(1443:227); Bairos V. (1445:200; 144S:52);
Cailqiiist ( 1465:231-233. in part).

Tdchycrcshnuhypteia. — Anonymous ( 1435:124).

lachycrcs /J/c/zcrcv.— Murphy (1436:144. 453-
95S. 964-465. 468-464); Bulloek (1436: 1 37);
Steullet and Deaulier (1436:367); Reed and
Philippi B. (1438:13): Lauhmann (1440:14-
20); Anonymous ( 1442:310; 1450:44); Housse
(1445:42); Trimble (1443:414); Delaeour and
Mayr ( 1445:15. 38; 1444:40. 42. 63); Philippi
B. (1445:144; 1464:47. in part ); Hellmayrand
Conover (1448:374-376); Olrog (1448:473;
1450:518; 1454:70; 1463:100: 1468a;lll:
1468b:plate 11; 1474:500; 1484:42. 264; (he
last live references evidently included both T
ptciicics and T. Icucuvepluiliis): "^ahe/
(1448:153; 1444:8. 10); Goodall cl al
(1451:162. 165. 167); Boetticher ( 1452:23. 68.
41): Pergolani de Costa (1453:36; 1470:35):
Verheyen (1453a:384. 435; 1453b;463. 486-
487; 1455:2. 15; 1458:4); Delacour( 1454:270-
271. 274): Scott (1454:61: 1472:48); Philippi-
B. Cl ill. (1454:24); Holgersen (1457:54);
Moynihani 1458:183.201 ); Lysaght( 1454:284.
312); Van Tyne and Berger (1454:233:
1476:347); Wooltenden ( 1461 :4): Schonwetter
(1460:132); Berndt and Meise (1462:142);
Godoy (1463:31): Humphrey and Clark
(1964:186); Bernath (1465:48); Johnsgard
(1465:44; 1468:105; 1478:136. in part:
1474:452. in part); Johnson (1965:145):
PettingilH 1465:71 i; Smith ( 1465:55): .lohansen
( 1466:23 1 ); Meyer de Schauensee ( 1466:40. in
part; 1470:32. in part; 1482:32. in part);
Stresemann and Slresemann ( 1 466:305 ); Ciew all
(1468:188); Griswold (1968:32); Lack
(1468:347: 1474:85); Schmidt (1464:125);
Weller ( 1464:128; 1475h:86; 1475c:110;
1476:45): Humphrey ct al. (1470:124-137);

Markham (1470:45. 48; 1471:22); Raiki)w
(1470:570; 1485:82); Barros V. (1471:172);
Bock (1973:208-204); .lehl (1473:124:
1475:546); Pisano V. (1473:42); Texera
(1473:245-247): Vigil (1473:64, 71. in part);
MacLean (1473:24; 1474:143); Merne
( 1474:34.79); Morony ctul. ( 1475; 12): Woods
(1475:122): Brush (1476:482. 485): Gruson
(1476:11); Jehl and Rumboll (1476:146);
Kuhnemann ( 1 476; 1 57); Venegas C. ( 1 476: 1 77-
180. 183: 1481:216-217; 1486: 1 1 .61 ); Wolters
( 1476:48); Blake ( 1977:227. in part): Daskam
(1477); Jacob (1977:52-58; 1482:87); Navas
(1977:35-36); Navas and Bo ( 1977:74); Reed
(1977:27): Sielfeld K. (1977:285. 294):
Clements (1978:28); De la Pena (1978:58;
1986:80. in part); Soothill and Whitehead
(1978:281); Boswall and Maclver (1979:75):
Goodall (1979:76): Todd ( 1979: 160); Venegas
C. and Jory H. (1979:72); Clark (1484:212-
213: 1486:100, in part); Howard and Moore
(1980:71; 1984:71); Erize cl al. (1981:178);
Gotch (1981:83): Humphrey and Thompson
( 1 98 1 : 1 . 3. 5-6. 10); Araya ( 1 982:5 ): Humphrey
and Live/ey (1482a:l-2. 21-22; 1482b:368.
370-371: 1485:444-451); Jacob and Ziswili
(1482:274. 276); Livezey and Htimphrey
(1482:12-16; 1983:485-486; |984a:257;
1984b:368-373: 1985:154-155; 1986:540-549.
552. 556); Mli'kovsky (1982:728); Scherer and
Hilsberg (1982:360); Carpi ( 1984: 1 16. in part):
Daciuk and Heber (1984:174. m part); Kolbe
( 1484:66. 170-172); MendalU7(//.( 1984:306):
Walters (1984:18); Edwards ( 1985:21 ); Araya
M. ct <//. ( 1986:1 16. in part); Livezey ( 1986b:
512; 1986c:458, 460-466; I989a:l. 3. 6-15.
20-22,24-27.31-33.41: 1989b:182); Livezey
(7 (//. (1986:445-448. 450): McGowan (1986:
305); Yamashina (1986:70); Narosky and
Yzurieta ( 1987:79); Wolsey (1487:39); Chebez
(1988:26): Gauthier (1488:113): Madge and
Burn (1488:58. 181); Ryan (7 <//. (1488:24,31.
33); Sibley and Monroe (1990:32).

lachxcrcs pahulioniciis. — Junge (1934:166. in
part).

*Tacltcrcs picitcrcs. — Vera ( 1974:1 ).

■Taciixcilcs ptcncvcs. — .^dams and Templeton
(1979:38).

32

UNIV. KANSAS MUS. NAT. HIST. MONOCKAril NO. S

Vhrnaciii.,'\k Nami-.s

/-.';; i,'//.v/)

Shorl-wingccl niicropierus, — Eyton ( 1S.^S:I44).
C'oninion Steamer. — Finn ( 1924:139).
Magellanic Mightless Steamer Duck. — Murphy

(1936:954).
Flapping loggerhead. — Bridges ( 1948:97).
Flightless Steamer-Duck. — Narosky and Y^uneta

(I9S7:79).

Spiiiiisli

i'ato vapor que no vuela. — Bullockt 1936:137).

Palo quetro.— BaiTos V. ( I945:2()()).

Palo quetru.— Housse ( 1945:92).

Remero \elo/ sin alas. — Housse ( 1945:92).

Pato vapor magellanico. — Delacour and Mayr

(1949:631.
Palo quetru no\olador. — Goodall (7(//. ( 1951: 165).
I'alo vapor no volador de Caho dc IhMiios. —

Pergolani de Costa (1953:36).
Palo vapor comun. — Oirog (1959:70).
PaH) motor.— Barros V. (1 97 1 : 1 72 ).
Pato vapor grande. — Vigil ( 1973:69. 71 ).
Pato vapor de mar.— Vigil (1973:69).
Pato-vapor austral. — Narosky anil Y/uriela

(1987:79).

Diilcii

Sloombooteenden. — Blaauu ( 1912b:7).

Gerniaii

Reiscndamiilschiffente. — Berndt and Meise

(1962:1921.
FlugloseDamplschitlente. — Johansent 1966:231 ).
Magellan-DamptschilTente. — GevvalK 196S:18S):

Wollers (1976:98).

rrcnch

Microptere cendie. — Oustalet ( 1891:229).
Canard-vapeur de Patagonie. — .lohnsgard
(1978:136).

Czeclioslovdk

Kachyne parm'kova.— Kolhe (19S4:17()).

Russian

MorenjioHOBo yxKii nopoxoa KollxM 1984:

170).

Japanese

-Yamashina i 1986:70).

Fucfiian ( tanfian)
Alakuch.— Phillips (1925:288).
.Macush.— Reynolds in Lov\e ( 1939:471).

I- in':^iiiii iOna)

Aloksh.— Reynolds /// Lowe (1934:471).

/• iici^ian i Yamuna)

Alakush.— Barros V. (1971:172).

Okiciwi Dt s(KM'I1()\ anoT'iPE

This species was prohabl\ the s]iecies lirst ob-
served by European explorers (Sarmiento de
Gamboa in 1582). contrary to the claim by Sclaler
and Salvin ( 1876:402) that the genus was discov-
ered by Europeans in the Falkland Islantis. ant! it
was this distinctive flightless form against which
the flighted form \\as compared and ultimatel\
distinguished as specilicall\ distinct (e.g.. King
1831. Oustalet 1891. Blaauv\ 1917. Lowe 1934).
This species was segregated from its Falkland
flightless congener by Murphy ( 1936). The origi-
nal description by Forster (1844:338-340) was
e,\ceptionall\ detailed, including mention of its
flightlessness. descriptions of phnnage patterns,
colors of soft parts, anatomical iletails of the bill
and feet, counts of rectrices and remiges. its Ma-
gellanic disinbuiioiial range, and a \ ariety of mea-
siuements. including an (unfortunateh exagger-
ated) boih weight ( 16 libras. 7-8 kg).

No holotvpc lor /'. pwneies was designateil.
Purporteil civt\ pe material for suppressed Oideiiua
pahicluiniiii \\ascited b\ Stenhouset 1929. 1930).
WaiTcn ( 1966). and Warren and llarrisiin ( 1973).
Consequeiuly. we designate as iieot\pe the fol-
lowing skin specimen, held at the .American Mu-
seum of Natiual History. Nev\ \o\\:

Specimen no. 443669 — Male: collected at Isla
ChMoe. Chile: on 19 May 1914; by R. H. Beck.

SfANtJARt:) Mkasiiri-mi-nis oi- Adiit.s
(mean + standard deviation, range, n)

Total wciiilii (g).— Males: 5394 ± 392. 4950-
6500. 16. Females: 4184 ±463. 340()-50()(), 17.

STEAMER-DLICKS (ANATIDAE: TACHYliKIS)

33

\l m:^ Icir^thiiux. mm ).— Males: 273 ± 1 2. 243-
2^)4. 3S. I-emalcs: 262 ± 1 1. 235-282. 2S.

Ctilmcii Icir^ili (mm I.— Males: 59.4 ± 3.S. 54-
70. 37. Females: 5S.4 ± 3.4. 50-63. 30.

^(//7 ir;<///; (mm).— Males: 16.1 +0.9. 14-lS.
37. Females: 15.3 ± O.S. 13-17, 30.

Tarsus Icir^ih (mm).— Males: 71.4 ± 3.S. 65-
79. 37. Females: 67.5 ± 3.2. 62-75. 30.

Tail lcii;^lli (arc, mm ).— Males: 98 + 8. S3- 1 1 2.
14. Females; 87 ± 7. 73-106. 27.

MEASliRHMF-MS (M\l) OP E(,GS (\ = 32)

Length. — mean = 82.7. range 78-88.
Width. — mean = 56.5. range 52-61.

Brief Description

This species is ihe largest ofthe steamer-ducks.
The bi)d\ is prednminantly battleship gray in as-
pect, and dilTers trom /, pahu lioiiuns. T.
Ic'iicocc'piialiis. and 7. Ivacliyptcrus in lacking
extensive chestnut on scapulars, sides, anil Hanks.
The lower breast, belly, and most secondaries are
white. The central tail feathers are slightly elon-
gate and recurved (Fig. 4). Males are larger and
more robust than females. Bill color of adults of
bi)th sexes is bright yellow-orange: bill is dark in
siibadults and Juveniles of both sexes.

There are two mi>lts and plumages per cycle,
the prebasic limit replacing the whole feather coat.
the prealternate molt replacing only the feathers of
the head and neck. The definitive basic and alter-
nate plumages are sexually dichromatic. The de-
linilive basic plumages of the head and neck of
neither sex resemble the juvenal plumage. Juvenal
plumage of head and neck (both sexes) is medium
to dark gray, lighter ventrally: there is a small
patch of brownish chestnut on the throat.

Definitive basic plumage: male — dark gray
crown, light gray cheek, indistinct postociilar
streak, small indistinct chestnut throat patch; fe-
male— head and neck medium-dark gray, short
faint postociilar streak, small indistinct patch ol
chestnut on throat.

Dehnitive alternate plumage: male — light gray
crown, rest of head and neck pale gray to white
with indistinct patch of pale cinnamon on throat;
female — crown dark i:ra\. cheeks iiKHlium gray.

short pale grav to \s hilish postociilar streak, chest-
nut patch i)n throat.

The class-! downy difleis Irom ilownies of all
oilier Taclncrcs in having the |iostociilar streak
divided, and the supraloral and supraocular
patches are very small (and separate) or lacking
entirely.

DisrRiininoN

Resident on marine coasts and islands from
immediately north of Isla de Chilotf. Chile south to
Tierra del Fuego. including Kla de los Estados.
Argentina, where H. M. Cadot. Jr. (pers. coiiini..
1971 ) found them to be the most common duck
(Fig. 7). Olrog ( 1963:100) stated that the species
ranges north to Concepcion. Chile, during winter,
but confirmatory specimens are lacking. Olrog
( 194S:473) suggested that T picncrcs nested also
on Lago Fagnano. a large inland freshwater lake
on Isla Grande. Tierra del Fuego, but no documen-
tary evidence was provided and Olrog deleted this
idea from his subsequent works. Contrary to the
statements of Olrog (1959, 1963. 1968. 1979.
19S4). Philippi-B. (1964:47). Smith (1965:55).
Meyer de Schauensee (1966:40: 1970:33). Vigil
( 1973:69). Woods (1975:122). Blake ( 1977:227).
De la PeiKK 1978:58: 1986:80; 1 987:40). Johnsgard
( 1978:137: 1979:452). Carpi (1984:117). Daciuk
and Heber( 1984: 174). Clark ( 1986; 1 00). and Araya
M. (7 (//. ( 19X6:61 ). there is no specimen to docu-
ment that 7. picncrcs occurs, even during winter,
on the Atlantic coast north of Rio Grande. Isla
Grande. Tierra del Fuego. The idea that T picncrcs
occurs on the Atlantic coast of Patagonia may
represenl. in part, confusion (iii Chubiii) with
llightless T Iciicdi cplhiliis or the reluctance of
many T. paiac/uniicus to take llight. but it appears
to have had its origin in the vague, partially incor-
rect delimitation of its range given by Murphy
(1936:199); "The distribution of Ihe mainland
Flightless and Flying species lar:.^cl\ n'linulcs
iliniii:;li(iui a range extending from I'uerto Deseado
on the Atlantic, southward to Cape Horn.... The
Fliizhtless species. ..IS nurnhilly abseiil Irom the
whole eastern part of 1 ierra ilel Fuego and the
.Atlantic coast of Patagonia. Most of the steamer
ducks 111 these districts represent the Flying spe-
cies lemphasis added]."'

34

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

Fig. 7. Detailed map of the distribution of/', piciwivs based on specimens, published records, and adequately
documented, unpublished observations. Specimens are shown as solid circles, sight records as open circles:
evidence ofbreedini; (nests. bro(Hls) is indicated bv diuiional slashes.

STEAMER-DUCKS (ANATIDAE: TACHYERES)

35

TaCIIYIKES EEICOCEI'IIAEI S

HUMPHRKY AND TH()MI•S()^ 1981

WhITK-HRADKI) FLKiHTI.KSS SiEAMKR-Dk K

Taclncirs piciwns—0\wi (l^SM:?!); 1M63:1()();
1968:111; 197'):5()(); IMS4:92. IM: in part, sec
under T picncics): Meyer de Sehausensee
( 1966:40. in pari; l')7():.32.inpart); Vigil ( 1973:69.
in pari); .lulinsgard (1978:136. in part): Carpi
( 1 984: 1 1 6. in part ): Daciuk and Heber ( 1 984: 1 74.
in pari): Araya M. ct <//. ( 1986:61 . in part): De la
Pena 1 1986:80. in part).

'■■'Tcniiicrcs jniuulioniviis. — Korschenewski
( 1969:52; may have included T.pahichdim us).

Tachycrcs pnuu linni( us. — Boswall and Prythercli
(1972:12.";); Boswall (1973a:33); Jehl ct <//.
(1973:58. (il. ni part); Daciuk (1976:27-29;
1977:363. 371. in pari, probably included /'.
paicuiiiinit IIS): Bosuall and Maciver( 1979:75-
76.78).

Tcniiyvivshnu livpicnis. — Oirog( 1979:50. in part).

Tachycrcs Icm m cpluiliis . — Humphrey and
Thompsdn ( 1*^)8 1 :3-fi. 8.10); Humphrey and
Live/ey (1982a:l. 21. 22; I982b:368. 37;
1983:4; 1 985:944-95 1 ); Live/ey and Humphrey
(1982:12-16; 1984a:257; 1984b:368-369.371 .
375-376; 1985:154-156; 1986:540-552.554);
Meyer de Schauensee and Mack (1982:431.
438): Straneck ci ,il. ( 1982:256); Howard and
Moore ( 1984:71 ); liduards ( 1985:21 ): Live/ey
('/ <;/. (1985:18-19; 1986:445-450); Raikow
(1985:82); Live/ey (1986b;512; 1986c;458.
460^63. 465-466; 1989a: 1 , 3. 6-7, 9-15. 20-
23, 25. 28. 31-33. 41 ); Humphrey cl al. ( 1987:
68-69); Narosky and Y/urieta (1987:79);
Madge and Burn (1988:58, 182); McGowan
(1989:538-540. 542); Sibley and Monroe
(1990:32).

'■■Tcichycrcs Icinin cpluiUi. — Corbiii ( 1MS3:216);
Kolbe (r)84:i7(). 171).

Vi;RNA(iir\R Namii.s

White-headed Flightless Sleamer-Duck. —
Humphrey and Thompson ( 1981:3).

Chiibut .Steamer-Duck. — Narosk\' and ^■/urieta
(19X7:79).

Vvhitc-lace(d) Steamerduck. — McGowan ( 1989:538-
539).

\/>(/;».s7/

I'ato \apor iioi -palagc'inico. — Eri/e cl <//.

(l')8 1:148).
Pah) xajioi no volador de cabe/a blanca. —

Humphrey and Live/ey ( 1985:944).
Palo-vaporcabe/;i blanca. — Narosk\' and Y/ureita

(1987:79).

Originai. Di scKii'iioN andTi'I'i:

This species was recogni/ed as specifically
distinct only in 1980 (Humphrey and Thompson
IMSO) and described by Humphrey and Thompson
(1981). although specimens of this form were
observed and collected infrequently during the
19('i()sand 1970s: a single skin specimen was taken
as early as 1 886. Humphrey and Thompson ( 1 98 1 )
diagnosed the species using a combination of its
intermediate external measurements (body inass,
wing-loadings, and lengths of the culmeii. tarsus,
and middle toe), two qualitative osteological char-
acters (robustness of the humerus and caudal
breadth of the sternal basin), the largely white
head of adult males in alternate plumage, and the
comparatively broad white postocular stripe of
adult females in alternate plumage.

The holotype (skin specimen) was designated
by Humphrey and Thompson (1981 ) and depos-
iteil at the Museo Argentiinule C'iencias Naturales.
Buenos Aires. Argentina:

Specimen no. 52694 — Male; collected at Puerto
Melo. Chubut. .Argentina; on 24 September 1979;
by M. C. Thompson and P. S. Humphrey.

Si WDAKII Ml ASI RIAII \1S (11 .Am lis

(mean + standard tle\ iation, range. //)

lonil nci'Jil (g).— Males: 3808 ± 491. 2600-
4400. 19. Females: 3013 ± 295. 2450-3550, 16.

ll;/;-/<7;.i,'///(arc.mm).~Males: 281 ± 10.262-
295. 14. Females: 273 ± 10. 255-290. 13.

Ciilnicn Iciv^ih (mm). — Males: 55.9 ± 2.9. 51-
63. 16. Females: 55.8 ± 1.5. 54-59, 13.

/V(»7 M7<//// (mm).— Males: 12.4 ±0.8. 11-14.
16. Females; 11.8 ±0.8. 10-13. 13.

36

UNIV. KANSAS MLS. N.\T. HIST. MONOGRAPH NO. S

7(//-.v((,v Icir^ih (mm). — Males: 64.8 ± 1.4. 61-
69. 16. 1-cmalcs: 62..^ ± 2.3. 5M-66. 1 .v

Tail Iciv^lh (mm).— Males: 97 ± 10. 7S-I()9. 7.
Females: 94 ± 6. 83-101. 7.

Mr-;ASi'Rf-;Mi:NTs (mm) oi- Eggs (,v =15)

Lcii'^rh. — mean = 81.2. range 72-86.
Wulili. — mean = .54.2. range 51-56.

Brihi- Dkscription

The b()il\ IS predominantly hallleship gray in
aspeel with ennsiderable dusky brown on scapu-
lars, sides, and thinks: lower breast, belly, and
most secondaries are white (Fig. 4). Central tail
feathers are slightly elongate and reci.n'veil. Males
are larger and more robust than females. Bill color
of adult males is bright yellow-orange: it is darker
yellow-orange in adult females and subailiills and
juveniles of both sexes.

There are two molls and plumages per cycle,
the prebasic molt reiilacing the whole feather coat,
the prealternate molt replacing only the feathers ol'
the head and neck. The definitive basic and alter-
nate plumages are sexually dichre)matic.

.luvenal plumage: head and neck (both sexes) is
dark brow n.

Deliniti\e basic plumage: male crown dark
gray, cheeks reddish-brow n, broad white postocular
stieak, large cinnamon patch on throat: female —
heail antl neck dark brown with small, while
postocular streak.

Dehniti\e alternate phmiage: male — head and
neck predominantly white: crown, lores, and ante-
rii>r cheek gray in some individuals, with small
patch of cinnamon on throat: female — crow n gray,
cheeks brown: long, uninterrupted, prominent
while pi>stocular streak.

Class-I dow ny differs from clow nies of all other
liicliycrcs in having the supraloral ami supraocular
patches v\ide and continuous with the wide
postocular streak.

DiSTRIlU TION

I leiuiH epiialits is limiled in distribution to
coastal Chnbui. .Argentina, from Peninsula Valdes
south through the Bahi'a de Camarones and Bahi'a
de Concepcion to the northernmost regions of the
Colli) San Jorge (Fig. 8). Within this limiieil range,
at least during the breeding season, this species is
by far the most abundant species of Tcicliycirs: it
may be that the \er\ similar /'. iniUic/ioiiicii.s oc-
curs in this area only as a (non-breeding) straggler
iluriim the breedinsz season, or durinii w inter.

MOLTS AND PLUMAGES

Hisioin OK Sum

Gi-:ni-:rm. KnowlI'DG,!: oi^

AnAIII) Pll AlAlil s

The early exploreis of soLilhenimosi South
.America aiul (he I-alkland Islaiuls ikiring the I7tli
and 1 8tli centuries w ere not liamed ornithologists.
Nevertheless, they coiitribuleii a great deal to
early understanding ol the distribution ami habits
of steamer-ducks. Many of those who worked on
steamer-ducks in the 19th ami early 20lh centu-
ries— whether in the held or with museum speci-
mens— were ornithologists by training or experi-
ence, or. at lhe\er\ least, naliiialisis. riiereloie. it

is useful to assess the state of know leilge of molts
and plumages of waterfowl in the 19th and early
20th centuries and ln)w this might have intluenced
the assumptions, preconceptions, and conclusions
of ornithologists of the period about the molls and
plumages of steamer-ducks.

Newton (1895), in his classic Dicrioiiary of
liinls. sialetl that knowledge of molts and plum-
ages of a great many species of Furopean water-
fowl w;is minierately advanced by the 19th cen-
tuiv even though, as he pointed out ( 1895:595):
"The literature relating to this branch of
ornithology... I was] very small.'" Nevertheless there
must have been considerable knowledge about the
molts and plumages ol those species of luiropean
waleiiowl that hail been huntetl for centuries for

37

■42° 67°W
S

66°

65° ^ 0064°

0 1/

63°

ARGENTINA

PROVINCIA DE
CHUBUT

ATLANTIC
OCEAN

I — I — I — I — r
50 KM

Gol f 0 San Jorge

-46°

Fisi. X, Dclailcd map ol the disinhution of T Icuccccplhiliis hascd on specimens, publislietl reeiirds, and
adeqiiatelv iloennieiiled. unpublished observations. Specimens arc shown as sohd circles, photographs as heavy
rings, and siglit records as open circles: evidence of breeding (nests, broods) is indicated by ihagoiial slashes.

IciikI or sport. The llightless cotuiilion ot water- durinj; the nesting and moiling seasons v,'ere passed

fowl during the sLiinmer following the nesiiiig in Hnglandiisearly as the 16th century (cf. Newton

season was well know n as early as the 1 2th century I SM.Si.sy? ). Popular and scientific knowledge about

and laws |irohihitiiig the hunting of waterfowl molts and plumages of many species ot European

38

UNIV. KANSAS ML'S. NAT. HIST. MONOGRAPH NO. K

walcrl'ovvl duiiiiL; iIk- I ''ill (.ciiluiN uas consider-
able, and it was known that nian\ species:

( 1 ) Are se\iiall> dichronialic:

(2) Exhibit seasonal dilterences in appearance,
\ i/,. males of sexually dichromatic species have a
bright plumage worn nn)st ot the year and assume
a brief, dull eclipse plumage dining the llightless
period t'ollowing the breeding season:

(3) Take two or three years before attaining
adult (definitive) plumage: and

(4). Have male 'eclipse" (basic) and teniale
plumages that are similar to or identical to the
Juvenal plumage.

The controversy thai most affecteti early under-
standing of molts and plumages in Tachyevcs was
the debate concerning recognition of one or two
species of steamer-duck. Most workers on steamer-
ducks during the IMth and early 20th centuries
were preoccupied with this taxonomic problem
and not with interpretation of molts and plumages
per sc. In addition, most of them knew little or
nothing about the molts anti plumages of waler-
fov\l and ignored the subject except insofar as
descriptive data concerning plumage aspects ap-
peared relevant to the taxonomic question.

There were, however, a lew workers (e.g..
Oustalet. Blaauw. I'liillips. Chapman, Lowe.
Murphy) who presumably were knowledgeable
about the molts antl plumages of European and
other northern-hemisphere waterfow 1. Their inter-
pretations of the molts and plumages of steamer-
ducks, however, either did not take this knowledge
into account or were based on certain preconcep-
tions concerning southern-hemisphere waterfov\ I.
Because sexual dichromatism is weak or lacking
in several southern-hemisphere species, these
workers inay have assumed that all southern-hemi-
sphere waterfowl had only a single molt and one
sexually monochromatic plumage per year. These
workers, too. were preoccupied w ilh the problem-
atic taxonomy of steamer-ducks.

Even with good series ol' specimens of known
age. a resource not available to ornithologists in
the 19th and early 2()th centuries, understanding
the variation in plumage pattern of an\ species of
waterfowl is diflicult. lurthermore. until re\ iew
of the genus b\ Murphy ( 19.^6). the whole prob-
lem was confoundetl bv substantial taxonomic

uncertainties. In what follows, we examine the
growth ot know ledge anil interpretation ol |iluni-
ages and solt parts of steamer-ducks in three eras:
(1) Era of Exploration. (2) Era of Taxonomic
Controversy, and (3) Era of Murphy.

Er.a of Expi oRvnoN

From the 16th into the 19ih century, steamer-
ducks were treated as a single species and descrip-
tions of their plumages were typological. Three
important points characterized this period: ( 1 )
descriptions of steamer-duck plumages v\ere not
associated with an\ taxonomic controversy: (2)
steamer-ducks were universally understood to be
llightless: and (3) it apparently did not occur to any
of these early workers that sieamer-ducks might
have more than one plumage a year.

The explorers and naturalists of this period
variously observed and collected specimens of
steamer-ducks in the Magellanic region of south-
ernmost South America and the Falkland Islands,
and the cabinet naturalists of the day examined
specimens collected in these regions and took
account of the notes made hy the collectors. Al-
though some of the resulting descriptions of
steamer-ducks were more detailed than others, all
of them captured the essential generic features of
a steamer-duck, namely that they were large, gray
thicks w ith underparts and secondaries white, and
\ellow or orange bill and feet. Some accounts
mentioned the orange wing-spurs (Forster 1777).
ami iris color as red brown (Forster 1777) or
orange (Latham I 7S5).

The description hy Forster ( IS44i of the plum-
age pattern ol Tucliycrc.s lAiuisi pteneres was an
exceedingis detailed account that, in its careful-
ness and attention to detail, w as a century ahead of
its time. His account of the structure and colora-
tion of the bill and feet was exceptionally thor-
ough. In addition. Forster described the white on
the secoiuiaries in great detail on a feather by
leather basis, and he was the lirst to have noted that
the lower breast, abdomen, and under tail coverts
are yellowish- white (ochroleuca). an evanescent
color not preserved in museum specimens. Forster
also was exceptional because he specified the sexes
of the specimens he described. He characterized

STEAMER-DUCKS (ANAIIDAE: TACHYHHhS}

39

lliL" hoaci ol the male as lulcsccnti-alhiiin willi tin.'
eye icgiDii wliilc and llic upper neck silk\ while
(sericeo-alhus): he stated that the head and neck ol
the female are cinereous and the eye region is
while.

Other descriptions of the plumage and soft
parts of steanier-ducks by early explorers and
naturalists were few in number aiul t\pically not
sex-specilic (e.g., Forster 1777. Latham 17X5.
Bonnaterre 1 790. Buffon 1 S 1 2. Quoy and Ciaimard
1X24. Knig IS2X). Quoy and Gamiard ( 1X24) vis-
ited the Falkland Islands in February. March, and
April, and their account was the only one that
mentioned red on the throat and bieasi; their de-
scription e\idently concerned '/'. hrachypicrii.s.
which, although indistinguishable from /'.
putiU lu'iiu lis in color pattern, was the species
most frequently encountered in the coastal w aters
of the Falkland Islands. None of the early explorers
and naturalists mentioned downs \oung steamer-
ducks and |u\eniles. and none indicated any differ-
ences between the sexes in soft part colors.

Era Ol- Taxonomic Controvkrsv

Accounts of the molls and plumages of steamer-
ducks from the early IMlh century until 1436 in-
cluded considerable new information about de-
finitive. immature, and downy plumages, sexual
dimorphism, and interspecitic differences in plum-
age coloration and pattern of adults. Although a
greal man\ specimens of steamer-ducks were col-
lected during this era and many descriptions of
their plumages were detailed, the consensus con-
tmued to be that steamer-ducks had hut a single
plumage per year.

Interest in the taxonomic issue led several natu-
ralists of the time to characterize phenotypic dif-
ferences more enthusiasticall) than they might
have otherwise. Because T. initiuiioiiiiiis and /'.
Ivin lixph'i us are virtually indistinguishable in the
held and diflicult to tell apart as skin specimens,
ourdisciission here will focus primarily on findings
related to the continent, i.e.. comparisons of /
/)<//(/<7;()///(//.v with 7". /)/(';((';c.s. Whether interpreted
as taxonomic or age-related differences, many of
the characteristics of T. pahuhunit ii\ and I.
ptciwrcs were included in these early descriptions.

Characteristics (.if .'Xdult /. pauu luinuns

.Adult 7. paiacluinu us was described by vari-
ous authors (under the names hracliypterus and
cinercus) as differing from adult '/'. piciicrcs in
being smaller, having redder feathers on throat and
scapulars (King IS.^I. IX.^9; Lesson 1X37;
Cunningham lS7lb; Phillips l')2.'i)and in having
leathers of back, breast ami Hanks, scaly in appear-
ance because of their dark borders and silvery
centers (Oustalet 1891 ). Cunningham ( IX7lb:9.'>)
wrote that "...Younger individuals (M.
FdliU hdiiu us) are chietly dislmguished by. ..their
greenish-black bills...." Cunningham, of course,
believed that there was but a single species of
steamer-duck of v\hich \ounger iiulis itiuals (called
by other authors patui iiauu us) were capable of
flight.

Oustalet ( 1X91 1 observeil \w differences in bill
color between male and female T. paliuiunmus;
he noted only that in 7". pakicluuilciis the colora-
tion of the beak is generally less li\ely and more
uniform than in /'. plcncrcs. Although Oustalet
( I X9 1 ) presented six comparative statements con-
cerning the differences between 7. ptowics and T.
piiiacluuiicus (using older generic and specihc
names ). Blaauw ( 1 9 1 2. 1 9 1 6. 1 92 1 ) w as the Hrst to
succinctly compare adults of T. plcncrcs (his
t iiu'irus ) and 7". patacluniicus and describe sexual
dimoiphism in the two species. ¥oxT. patch lu uncus.
Blaauw ( 19l2a:47— IX) wrote that "...both sexes
are much smaller than the preceding one \T.
picucrcs] and the female is miich smaller than the
male. The /t'/»t//c' is also coloured quite differently.
1"he male. ..is clear grey with a white breast and
clear yellow bill. ...The female is much smaller
than the male. The head is brown and the rest of the
body of d beautiful wine colour w iih \\ hile breast."
Blaauw (1916:491) noted later that the female
"...is of a beautiful dark wine-colour, with grey
centres to the feathers of the upperside and sides.
The bill. ..IS brown or black." He ( 1916:491 ) also
stated that "...A pair [T. patacltc»iicus\ invariably
consisted of a large clear grey birti with a ncIIow
bill, ami a much smaller brown one w ithdark bill."

Scott and Sharpe ( 1912:492) recogm/ed only
one species of Taclixcrcs and considered T.
paiachnnicus the immature of the tlightless spe-
cies (7, plcncrcs) "...which seems not lo attain full

40

UNIV. KANSAS MUS. NAT HIS I MONOGRAPH NO. 8

adult plumage until at least the second and perhaps
the third year of its lile: moreover, the first breed-
ing is probably accomplished in the phase ot'plum-
age called by Dr. Oustalet M. putachoiiiiiis." Scott
and Sharpe provided a detailed description ol a
male specimen, now in the collections ot the Field
Museum of Natural History, which was collectetl
at the mouth of the Rio Negro in February I S')S.
Based on our examination of this specimen, the
bird was undergoing prebasic molt and the rem-
iges had not attained their full growth. Scott and
Sharpe (1912) described the colors of the soft parts
as follows: "Bill: Horn-color, shaded with blue and
green, the nail abruptly black. ...The feet and legs are
dull greenish brown, strongly shaded with orange."
This description and that of the feather coat indi-
cate that this specimen was molting into dehnitive
basic plumage. Although predicated on a mistaken
concept of phylogenetic relationships. Scott and
Sharpe (1912:492) insightfully commented that:
"The change of color to orange or cadmium-yellow
in the breeding season is to be looked for, as similar
changes in the colors of the bill occur in other allied
sea-ducks." As far as we can tell, this is the lirst
recognition of the fact that colors of the bill and feet
in detinitive male /. paunhonicus become duller
during the prebasic molt.

Phillips (I92.'i) was aware of the problematic
taxonomy of steamer-ducks and divided his de-
scriptions ot adult birds into those pertaining to
three "phases" conesporuling to the three species
to be recognized later by Murphy ( 1936). Phillips
(1925:2SS) described adult red-phase specimens
{Tachycrcs paraclianiciis) as follows: "Many of
these birds (I have studied some forty-three speci-
mens) do not suggest youth. They are mostly
uniform in coloring, with adult tail-feathers, and
in many cases the carpal spur is well developed.
There are no apiiarent se\ ilitfereiices....Bill. in
life yellow isli above, aiul bluish or greenish below
nostril, nail black. In dried skins nearl\ always
dark lead-colorall o\erculmen. sometimes slighil\
yellowish towards base, but never yellow all over
as in Tciiliycrcs ciiicivus....\.ciis and feet yellow-
ish, very nearl\. if not tiuite the s.inie as in Tth li\crr.\
cincrciis." liecause Philliiis noted no sevual tlillei-
ences. we judge that most of the males in his series
of specimens must Iki\ e been in basic plumage.

Chapman ( l933:.Vil ) noted that "On January
24. 1^)24. on a iresh water pond in northern Tierra
del Fuego. 1 saw a pair of adult Quettros (the male
w ith the head and neck white i accompanied by one
young about a week okl. both of which adults,
when Hushed, took wing easily and flew out of
sight toward the sea." This is probably the first
description of a male T. patdi Ixmii iis in supple-
mental plumage.

Characteristics of 7'. picucrcs

Cunningham (ISTIb:^,^) described the plum-
age of 7'. j)!cncrcs. w hicii he considered to be the
adults of a single species of steamer-duck, as
"...The bill is orange-yellow, with the unguis black.
The head is cinereous, becoming gradually paler
as the individual increases in age, with a small
patch beneath the eye, and a streak above it. nearly
white. The whole of the upper surface, the throat,
the superior part of the breast, with the exception
of a white speculum, are lead-gray. The lower part
ol tlie breast and abdomen vary from a lint \erging
on primrose-yellow to pale yellowish-while: and
the legs and feet are dark yellow ."This description
is notable because: ( 1 1 Cunningham apparently
did not consider the species to be sexually dichro-
matic: (2) he attributed variation in color of the
head to \ ariations in the ages of adult birds: and (3)
he noticed the evanescent \ellow bloom on the
lower breast and bell\.

Oustalet (ISMI) examined ten specimens of
w hat he called Micmptenis cinereiis. all of which,
from their localities, were T. ptencrcs. These speci-
mens were descrilied as having gray to bluish gray
heads and that the rest of the body except for the
lower breast and bellv was gra>. paler on the sides
and Hanks, and darker on the back, and without
an\ trace ol red. Bills of both sexes were yellow-
orange with nail black. Comparing 7'. picucrcs
w ith 7. patiuhoniciis. Oustalet noted that the fun-
damental colors of the plumage of the adult are the
same. He considered the colors of T. ptencrcs as
generallv less distinct than in T. paluclioniciis and
that the gra\ color ol the plumage of T. picucrcs is
not as dark as in / patm honiciis and the feathers
of the back, breast, and flanks lack the scaly ap-
pearance I ound in I jhiiiK linnic us. I'i nails, Oustalet

STFAMER-DUC-KS (ANATIDAE: TACHYERES) 41

notcti llial the reil iir reddish tiiu ol Ihc ihioiil anil some tletail. iiicludnig colurs ul bdl and Iccl. hut

bivasi nT /,/ii//(/<7/(i/;;( ;/.s isahnosl al\\a>s lacking lUilL'd (p. M5) of Ihe female i)iil\ llial il was

in 7'. piciwrcs. ■"Similar Ui the male, hiil somevv hat smaller." Nicoll

Snbseqnent deseripiions h\ Salvadori ( IS')5). ( |M()4) and Evans ( I9(W) described both sexes of

Nicoll (l')()4i. Blaanw (im2, 1416. 1421). /. /vc/zc/cv (under V. (7/(c/f/(.v) as having orange or

Mogensen ( 1917). and Phillips! 1925) provideil in orange-yellow bill and feet, respeclively.

varying detail the same descriptive information as Blaanw (1412, 1416. 1421) was the lirst to

did Cunningham ( 1871 ) and Oustalet ( 1S41 ). indicate details of sexual dichromalism in 7'.

I'icncrcs. noting ( 1421:57) diat "...both sexes are

Sexual Differences of Adult T. paUhhi'iiinis giay: the male has a pale or pearl-gray head and

neck, and a bright yellow bill. In the female the

gray is duller, so that the head is not strikingly

iialer than the rest ol the bodv. The bill is also

Cunnineham (1871b) did not remark upon the ,, , , 'i •• n i i .

' vellow but not so clear in color. He did not

sexual dichromatism of 7. /'(//<;(7(r;/(/(7/,v. Oustalet ' ,.,,.. ■ u ..

' . mention anv difference in si/e between Ihe sexes.

( 1841 ) presented descriptions of SIX specimens ot .. ' ,,,,-,, ■, , , •,•

' . . ' 111 Mogensen ( 141 7) described male /./'fcHC/Y.va.s

Presumabl\ because of the small amount of
material available to them. Kiiii; ( 18.^1 . I 834) anil

T. pdidcliiinic us including one adult female and

bemg somewhat lighter than the female especially

one adult male. Althouszh his descriptions indicate ,~i i i i"i lur

' on Ihe head, but did not mention anv differences in

that the beak ol the temale was black becomin>;

greenish-brown at the base of the upper mandible

and that of Ihe male was light orange-yellow, he

made no note about sexual dichromatism in the

species.

The sexual dichromatism ol adult 7'.

pahu lioiiii us was clearly described by several

authors (Blaauw 1912. 1416. 1921; Mogensen

1417; Lowe 1434). Blaauw ( 1916:491 ) noted that: Juvenal Plumage of 7. pataclunmus

".\ pair iii\;iriabl\ consisted of a larue clear iirev

, . , ... I, ■ , .., , 1 " II u " There was no mention ot the juNenal plumaae

bird with a yellow bill, and a much smaller brown ' c , "

bill color. Phillips (1925:288) noted of adult te-
male 7. ptc'iu'ix's: "Size somewhat smaller; color
same as in male... .Bill yellow or yellowish but not
such a clear or brilliant yellow as in the male."
Lowe( 1934) stated that the adult feiiKile has '■head
and neck iirev. not much ilarker than."

one with a dark hill." Blaauw ( 192 1 :58) described
the sexual dichromatism of ;idult /'. patdchoincus

as follows: "The male is clear erav with a white

, , , I 11 , I, Vi ' I- 1 I "vounti" specimens which he identified as T.

breast and a clear vellow bill. ...The temale has a • ^ ^

ol steamer-ducks until the statement by Sclater
(1881:108) that "In all the immature birds the bill
is uniform black." Oustalet ( 1891 ) described two

brown he;iil. and the rest of the body is of a
beautiful vinac
bill is brown."

pdidi luiiiiciis. One of these, for which sex was not

, . .■ , , ,, I , u' , 11 ttiven. had the plumaae mixed with tufts of down

beautiful vinaceous color, with a white breast. I lie ^ *^ ^

on the back and on the wings but still show ing the

principal colors of the adult plumage and the red

tince of the sides of the head and breast. The other

Sexual Differences ot Adult 7. /'?(7;c;c.v " . u- u u i . ■ i. u e i i

' specimen, which he determined to be temale and

Most early descriptions of plumage pattern and younger than the first, was collected on 9 February

soft part colors of T. ptenercs did not address 1 883. The specimen had dark gray plumage with

sexual dichromatism ( Des Murs 1847, Cunningham blackish brown on the borders of the feathers, the

I 87 lb). Oustalet ( 1891 ) examined ten specimens head was uniform gray without a while streak in

of 7. plena cs. hve of w hich were determined to be the vicinitv of the eye. and there w ;is no white band

temales and one a male. He described both sexes on the w mg; the last obsers alion indicates tluil the

asha\ ing yellow oryellow-orange bills with black growing Juvenal remiges were still quite short,

tips and feet yellow or yellow-orange variably Lowe ( 1 434:476) stated that "When able to fly.

mollled w iili gray. and lor some time afterwards, young T.

Sahadori (1845) described an adult male in piihu Iidiiu us of both sexes are scarceK ilisiin-

42

UNIV. KANSAS MUS. NAT. HIST. MONOCKAPII NO. 8

guishablc liDm ihc aclull Icmalcs. In the inimaliirc.
however, the transocular stripe, although appar-
ently longer, lacks sharp contrast with the contigu-
ous plumage and is not clearly defined." Evidently
the "immature" plumage referred to by Lowe en-
compassed the post-Juvenal, pre-detinitive plum-
ages of the head and neck.

Juvenal Plumage of T. picncrcs

Nicoll ( 1M()4) collected in southern Chile west
of the Straits of Magellan three specimens of what
surely must have been I', ptcncics (the adult male
and female both had orange bills). One of the
specimens was a Juvenile with dark brown bill and
feet. Blaaiiw ( 1921:.57) noted that ■'In the young
birds |of 7". /)/('/;(';£'.s|...the plumage is tinged in
some parts with brownish gray, but not enough to
obscure the generally gray aspect. The bill color of
such young birds is mi.xed with a dark greenish
tint, and their legs are dark. These birds were
evidently young of the year, since they were under
the guidance of a pair of adults."

r^hillips ( U)25:2S8) stated that: "We know that
there are individuals which do not pass through
any red or reddish-tinted phase. Whether these are
exclusively the young of the gray phase C/i/r/nc/r.v
cincrciis) we do not know. A specimen in ju venal
plumage from Cape Horn with the primaries not
yet fully developed. ..is gray all over the upper side
and without the prominent wine-colored edges to
the feathers on the breast, sides, and Hanks. Abdo-
men white as in the adult; whole head and neck
gray with some lust color on the cheeks and lower
side of neck, but not nearly so dark or so ruddy as
in most examples of the red phase Crachycics
pcitaclutnii ii\). In other words, this young bird
does not look as though he were going to pass
through the e.xtreme dark and ruddy phase...." I Ic
noted further (p. 288) that the bill in this specimen
was "probably ilark greenish on the culmen and
lighter below. Legs and feel yellow. ..tarsus (1.^
(rather large for the red type). "

Downy Young of 7". pciuuhoniviis

Oustalet ( \W\ ) evidently had obtained speci-
mens ot downies of both T. pahuhoiiiiiis and T
ptcncics but appaicnily was unaware ol the tli-

agnostic features of the patterns of the head, and it
is not clear how he identified his specimens of
downy steamer-ducks. Oustalet ( 1891 i described
a downy steamer-duck which he identified as 7'.
pataclioniciis but his description could pertain to
either 7. paicnlKiiiiiiis or T. ptcncics. The bird was
a very young female (chick) still in down brought
in alive by the Luegians at Orange Bay on 1 1
Februarv 1 88.^. The iris was light brown: the beak
was black, becoming reddish on the posterior up-
per manilible and light horn at the tip, which still
had the egg tooth. The membrane between the
lower mandibles was yellowish; the tarsi were
dark greenish olive becoming blackish: the down
already showed the distribution of colors of the
plumage of the adult, notably the white streaks on
the sides of the head behind the eyes.

Oustalet described two other downies, collected
on 10 February 1 88.^. which he had identihed as T.
ciiicicus which, from his description, possibly
were /'. pataclioniciis. The specimens had beak
and feet blackish, head and body covered with
down but alreatiy showing the dominant colors of
the plumage ol the ailult. ami a large w hite super-
ciliary streak extended a little posteriori) along
the neck. He described yet another dow n\. a \ery
young I'emale brought in ali\e b\ the Fuegians on
26 January 1 88.^ which was identified as t. cincrcii.s
(but which also probably was 7'. patuchonicu.s).
The head and hocl\ were eniirel\ coveieil with
down which was brown abo\e with white on the
chin and abdomen, above and behind the eyes, and
on the sitles ol the neck w here there was a large
recurved band joining the light ct)lor of the chin.
Two even younger females were brought in alive
by the Fuegians on 12 Januar\ 188.v Here again.
Oustalet idenlilied them as 7. cincrcus but. from
his description. the\ probably wcvcT. pataclioniciis
because the\ each had a wide, while posiocular
streak.

Lowe ( I'J.M) was the lirsl to present an absc)-
lulely diagnostic description of the downv \(iung
of T. pataclioniciis. He (p. 481) described the
".Supraorbital stripe and posiocular patches" as
being "White, broad, more diffuse and continuous
(low n sides of neck. In two chicks a few days old
the jxilches w ere separated b\ a very narrow line of
brow n."

.STEAMER-DL'CKS ( ANAT1I5AE: TACfDTRES)

43

Do\ui\ ^DLinj: dI I\ pivnvn's

Cuiiniiighani (IX7lh:47) dcsL'ribcd a dcnvny
young, cicarh thai ol /, phiicrcs. as tbilows:
"...llic entire uppei" Mirtace ol the body, the sides of
the head, and a jnngel around tlie lower part of the
neek. were eo\ered with a yreN ish-black down.
while the under surface and a spot placed ob-
liquelv abo\e and behind the eye were white."

Oustalet (IX') I) stated that he could identif\
with certainty as M. cincreiis (i.e.. 7' picncics) a
number of \'oung individuals. Based on his text, it
is clcai that his certainl\ was misplaced since the
patterns he described for the heads ol these dow nies
all pertained lo T. pafcn ho/iiciis except for one
young male killed on (i l-ebruar\' I8S3. The last
specimen had the head and body still covered m
large part by down. The upper parts were brown,
the breast brow nish gra\. the bell\ white, the sides
of the head brownish gra_\ with a very liglith
marked postocular streak, wings reduced stumps
but showing a small while transverse band. The
beak and feet were blackish brown with some
yellowish spots on the sides of the toes.

Salvadori ( I Sy.S:.^?.^) describetl downy young
steamer-ducks as ha\ing; "Head. neck, breast,
upper parts, sides, and Hanks dusk\ gray; abdo-
men and underiail coverts white; two white spots
on the sides of the head, one behind the e\e on the
temporal region, and another lower diiwn behind
the ear-coverts ...." From his description, the downy
young in question was without question a speci-
men of T. picnercs. Scott and Sharpe ( l'-M2;442)
described young birds in dow n as having "...head,
breast and upper parts, as well as the sides and
flanks, dull slaty gray, with a brownish tone; the
abdomen and under parts and two spots on the
head behind the eye on either side are white or
cream> white." The specimens examined by Scott
ami Sharpe clearl\ pertained lo /. piencrcs.

Blaauw (1416) described the downy of T
pwncirs but his description was not diagnostic for
the species. Phillips ( U)2.'i:2X'-M described downy
young Tcniivcrcs as ha\ ing "lores and cheeks light
buffv brown shading lo almost white on sides of
neck, while abo\e. behind, and below the eye are
indetinite whitish streaks t(trming. with a slightlv
darker streak between the bill and eye. a definite
■face pattern.' " llie tlowmes Phillips described

wereclearlx those of /'/'/(•;«■;■(' .v. Lowe( 1934) was
the Hrst to compare unequivocally identihed. pre-
halching embryos; he stated (p. 4S I ) that downy T
picnercs had "No supraorbital stripe, postocular
patches white, not so broad or so diffuse, and
interrupted by a conspicuous belt of the general
dark coloration ot the crown."

Ornithologists during the era of taxonomic con-
troversy made several significant contributions to
knowledge of the plumages of Fuego-Patagonian
steamer-ducks. These included description of the
differences between adults of 7. pakichnnicii.s and
/ , ptciicrcs by several authors, regardless of w hether
ihe\ considered them one or two species. In addi-
tion, several authors described the sexual
dichromalism of T pitUicluiun us and the relative
lack i>f it in y. picnercs. Finally. Lowe (1934)
contributed substantially to the later taxonomic
resolution by Murphy (1936) b\. anmng other
things, definitively describing the differences in
the head patterns of downy young T. patachonivus
and /. picnercs.

Era of Mlirph'i-

This era started with the publication of the
classic twci-volume work Oceanic Birds of Smith
Anicruii b\ Murph\ (1936). which included a
landmark analysis of the taxonomy of steamer-
ducks. In addition to bringing the era of taxonomic
conirosersy about steamer-ducks to a close.
Murphy presented detailed descriptions of adult
and downy plumages of three species of Tachye res
based on an examination of a large series of speci-
mens and a synthesis of published and unpub-
lished information concerning the natural history
of each of the species. Subsequent ornithological
works were characterized by acceptance of the
conclusions presented by Murphy ( 1936) concern-
ing the taxonomy, plumages, and thsiributions ot
steamer-ducks. A number of problems remained,
however, and several of his conclusions (some
incorrect) profoundl\ mtluenced later WDrkers.

Number of Molts per C\'cle

Murphy ( 1936:941 i wrote thai "Males of no
South .American duck lia\c an eclipse plumage
which is so characteristic amonii northern-hemi-

44

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. S

splicic species." .AltliDuyli the ikuiiil- oI the so-
called "eclip-se" plumage was not understoDtl at the
time of his writing, a likely implication of this
passage is that linlixcrc, have but one molt per
year. Johnsgard ( I '■Ht2: 1 46) listed Tachycrcs as not
having an "Eclipse plumage present in males..."
hut listed the genus as having "Two molts of body
leathers per year." Weller (I96S:2()6) observed
that "Most southern-hemisphere ducks have plum-
age cycles which differ from northern forms by the
absence of the "eclipse" plumage. ...Some species
lack sexual dimorphism, others have sexual di-
morphism all year, and some possess the first non-
nuptial (basic) plumage strongly developed." It is
not clear from this passage whether Weller be-
lieved that most southern-hemisphere ducks have
but one molt and plumage per cycle. Nevertheless,
with respect to Tuvhyeies. Weller (1976) con-
cluded that variation in patterns of the head and
neck of male steamer-ducks is a function of age
rather than the result of different plumages in a
gi\en cycle, clearly implying that steamer-ducks
have but one plumage and molt per c\cle.

Intraspecific Variation Attributed to Age

Cunningham ( lS71b:95) noted for the ""adult"
steamer-duck that "The head is cinereous, becom-
ing grailiiall\ palei as ilie individual increases in
age...." .Although Murphy ( IQ36:9.'i7) did not e\-
plicitls state this principle of variation v\itli age, he
noted of the retldish spot on the throat o\T. piriicirs
thai ■■...Fletlgluiys and voung adults. ..show less of
n than thoroughly mature birds." L)elacour( 19.S4)
also acknowledged age-related, seasonal, and in-
di\idiial \ariation in I piciiercs.

Woods (197.^:1 IS), in his description ol /
hnu Inptcnis. staled that "Old males liaxe an al-
most completely u hite head, \\ hile vounger males
have a grey heail with white rt)iind the e\e continu-
ing 111 a cur\ e dov\ n the side of the neck...l-roni the
second year, an immature male grailually gams
more grey on the heail and more orange on the
bill." Weller (I976:47i staleil that: ""In I-l>ing
Steamer Ducks and l-alklaiui l-lighlless Steamer
Ducks, mature males are u hue headed...." lie also
slateti (p. 49) that '"On the basis ot plumage coloui
and behaviour ot I alkland island hinls, I suspect

that there are at least four age classes: yearlings in
large Hocks, birds two years or older in smaller
groups or roving pairs, still older non-breeding
birds u ith some white on the head of males resi-
dent on suboptimal territories, and white-headed
males that are successful breeders. I have too few
observations to Judge whether this pattern also is
true of Flying Steamer Ducks, but \ariation in
head and bill color of males suggests this possibil-
ity."" Weller ( 1976:46) also noted that adult males
of the Flying Steamer-Duck and Falkland Island
Flightless Steamer-Duck have the head: ""Whitish;
younger males with greyish or brownish face:
white eye stripe." For the Magellanic Flightless
Steamer-Duck, he stated (p. 46) that the head of
the adult male is: ""Uniform gray: whitish crow n in
older males. ■■

Navas ( 1977) noted of 7". pahichoniciis that the
oldest males are less rusty in general and ha\ e the
head and neck lighter gras or partialis or totally
white. Johnsgard (1978:138) stated of T.
hracliyptcnis that "Adult males have a head that is
predominanll) gra\ ami white (nearl\ pure white
in old males)...." Curiously, the only authors to
attribute intraspecific variation in head coloration
of males to season are Chileans. Goodall et al.
(19.^1) noted of 7". puitii liomciis that the male
during certain seasons of the \ ear has a v\ hite head.
The\ noletl also lor 7. /'?<7/crc,\ iluii the color ol the
head \aries a great deal b\ season being at times
ctmipletely whitish. Araya and Holman (I9S6)
noted of 7, pdUn licnii ii.\ that the male nia\ ha\e a
white head in certain seasons ot the \ear.

Mo\{ of Reniiges

\Iur|ih_\ (1936:M61) wrote that ""Most of the
atiulls 1 7'. pienvics] taken b\ Beck at Chiloe in
Ma\ v\ere in worn and molting plumage....ln these
and other examples some of the remiges had be-
come frayeil practically ilow n to the shall as a
result ol their lrec|uent battering against the water.
.Among most such binls the two outer-most prima-
ries were new. the inner ones at the |ioint ol being
shed in sequence." In his discussion about T.
pulai honiciis. Murphy ( 1936:971 ) noted that "".At
I ishuaia on .April 1 ...ailults in the \ icinit\ had lost
most of their rectrices. while the lemiues were in

STEAMER-DUCKS (ANATIDAE: TACHYERES)

45

ihc nmKi ol nioull. oki wiirii primaries staiulmy m
juMapoMluiii w ith fresh imes."

In eiintrasl, Slreseniann and Stresemann ( 1466)
found lliat in all three speeies of Tachycics the
primaries are shed smiidianeinisly. Of all the speci-
mens (if Tdchyercs we have examined in wing
nidit. we have seen only one individual, periiaps
diseased, in which the remiges were not hemg
replaced simultaneously {T. hnichypleius. male,
collected on Lively Island. 12 February l'-)84; KLI
8052 1 ). Simultaneous replacement of the remiges
is the rule in the family Anatidae; however, the
Ruddy-headed Sheldgeese {Chl«cpha;^a nihidi-
ccps) in Chile and Argentina typically undergo
sequential replacement of the remiges (Summers
I4S2). Other cases of non-simultaneous replace-
menl such as the one T. hrachyptcriis we exammed
must be considered anomalous.

leathers whatsoever. Later in March the soung
bird began to deselop contoLU leathers and by 1
.^pril its head. neck, upper back, sides and Hanks
were completely covered with Juvenal feathers;
there was still considerable down on the lower
back. By I April the primary remiges were c|uite
long but it cannot be determined whether they
were fully grown. This record indicates that the
young T. ptcncres. reportedly well fed. remained
"downy" for two months after hatching, did not
start to develop contour feathers until it was more
than two months old. and that the remiges prob-
ably were not fully grown until the bird was about
three months of age. This inference contrasts with
that for most North .American ducks, in which age
at hrst flight varies from 37 to 77 days and for most
species it is less than two months ( Pettingill 1 970).

Development of Fledglings

Murphy ( l'-).i6:y71 ) stated that "Fledglings ol
the flying species, no less than those of the flightless.
acquire their wing quills very slowly, so that they
only have barely sprouted primaries for a consid-
erable period after the down has entirely disajv
peared. Three of the flying species in this stage
were taken at L'shuaia on April I." Soolhill and
Whitehead (iy7S:2S()). writing about T.
paiaclioiiii IIS. stated that "The fledglings, just like
those of the flightless species, acquire their wing
quills very slowly. Even when the down hasdi.sap-
peared entirely, there is a considerable period of
time during w hich the primaries have only barely
sprouted." From the way in which this was stated,
we suspect that Soothill and Whitehead rephrased
the statement by Murphy ( 1 936) and that their com-
ments were not based on original observations,

Llnpublished notes by Abby Goodall (pers.
comm.. January 1 98 1 ) concerning the early devel-
opment of a downy T. plcnercs hatched from an
egg found at Harberton corroborate the idea that
fledgling steamer-ducks acquire their remiges ver\
slowly. Dated photographs of this bird, which
hatched on 5 .lanuary 1977. during the ensuing
weeks sht)w that from .5 January to 5 March the
young steamer-duck continued to be completely
covered w ith down and had developeil no contour

Resemblance of First-year Males
to Adult Females

Lowe (1934:476) was the lirst to note that
"...young r./i(/r(;(7;<»«;(:H,v of both sexes are scarcely
distinguishable from the adult females." Murphy
(l'-)36:464) noted for T. hracliyptcnis that:
"lounger males exactly resemble females.,.."
Murph\ also stated (p. 968) for T. puhu lunik us
that: "Younger males resemble females in the
extension of reddish coloration to the sides of the
head or even to the forehead and crown. The color
of their bills also resembles that of females."
Delacour ( 1954) also noted that young males re-
semble females in both 7' patch Iuhih us and T.
hiiicliyplcius.

Several other authors (Navas 1M77. Johnsgard
l'-)78. Soothill and Whitehead I '■178) noted that
immature males of T. patachoiiicus resemble the
female. Navas (1977) observed that immatures
resemble females, as do the youngest adult males.
Johnsgard (1978:138). in his description of T.
hiiulixptcrus, wrote that ".luvciiilcs and Hrst-year
birds resemble females but usually lack the white
streak behind the eyes, and second-year males
gradually acquire a grayish head and orange bill."
Woods (1982:49). also writing about T.
hracliyptcnis. stated that "First year birds resemble
the female but usualh lack the white head streak."

46

UNIV. KANSAS MUS. NAT. HIST. MONCXiRAPH NO. 8

Ciokk'ii ("ollai III /, hidi Inptenis

Murpin ( l'-).Vi:M.^.>lsialC(llliat '".An unique cliar-
aclcr ol' 7. hicu Inpicnis is llic more or less distincl
ring of glossv golden lealliers around the neck. It
i.s usually evident in females to a greater e.xteni
than ni males, hut no okl I-'alkland hirtls seem to he
without a traee ot it." In hi.s description of 7.
hraclivplcni.s. Murphy (p.'')64) wenton to say that,
in the adult male, "...neck with a distinct silken
yellowish or golden sheen never present in
plcncrcs...." He (pp. 964-M65) also stated of adult
lemales "...base of neck showing a glossy, golden
yellow ring, somewhat indetinite in extent, but
more pronounced than the same feature in males,
and peculiar to this species...."

Subsequent to Murphy, the descriptions of T.
hi\uli\p!cnis by several authors (Delacour l'-).'S4,
Olrog 19.^9, Pettingill 196.^, Johnsgard 197S.
Soothill and Whitehead 1978) mentioned the
"golden collar." Johnsgaid ( 1978;L^S) slated that
"//( ilic jicUI. this species can be separated from the
flying steamer-duck b\...a golden-yellow ish collar
at the base of the neck." .Soothill and Whitehead
( 197(S:2(S1 ) wrote concerning T. hia< liyptcnis that
males have "...more yellow around the neck than
T. ptcnercs" and noted of the female that "...the
yellow neck collar more pronounced."

We are pu//led by the alleged "golden collar"
of Falkland f-lightless Steamer-Ducks. We have
examined the series of skin specimens o\ this
species available to Murph\ at the American Mu-
seum of Natural Histor\ aiul have observed hun-
ilreds of iiuli\ iduals of this species at close range
in the Falkland Islands, including examination of
st)me 20 freshly collected specimens of atlults and
subadults of both sexes, without ha\ ing tliscerned
a pronounced golden yelk)w collar in either sex of
adults. It is noteworthy that several authors
(Cawkell and Hamilton 1 ')(> 1 ; Woods 197.^, 19X2;
Weller 1976), lamiliar wiih lalklaiul Flightless
Steamer-Ducks in the lieki, have not included the
"golden collar" in theirdescriptions ol the species.

COMMKNTS ON DkSCRII'HONS

Our stuilies ol ihc plumages and molts of
steamer-ilLicks and our protocols lor collecting

data on molt and plumage in the lickl w ere limited
and, in retrospect, unsatisfactory for two reasons.
[irsi, molt and plumage studies initially were a
low priority in our field work. Second, our precon-
ceptions concerning molts and plumages of south-
ern-hemisphere waterfowl, and steamer-ducks in
particular, prevented us from posing appropriate
hypotheses and designing efficient methodologies
for collection of data. These deficiencies have
limited our knowleiige of the molts and plumages
most seriously lor 7 plcncrcs and 7. Iciuocephalus.
Fortunatels, by 1 982 we had worked out many of
these problems so that when we had an t)ppe)rtu-
nity to visit the Falkland Islands we were able to
collect a limited series of specimens of T.
hraclivplcni.s in a way that enabled us to provide
preliminary documentation of the sequence oiniolts
and plumages in that species.

The preconceptions that impedeil our studies of
molts and plumages in sieamer-ducks during 1979-
1981 were the following:

( 1 ) "Males of no South .-Xmerican duck ha\ e an
eclipse plumage, which is so characteristic among
northern-hemisphere species" (Murphy 1936:941 ).

(2) Variation in pattern or aspect of the pluiTi-
ages of the head and neck of male steamer-ducks
is a funclum of age (Weller 1976) rather than the
result of different plumages in a given cycle.

(}) Waterfowl i>f the southern hemisphere in
general have "simple" rather than "complex" pat-
terns of plumage succession as implied by Weller
( 1968:209): "...fairl\ t\pical northern hemisjihere
patterns (of plumage sequence) are apparent in
southern Cinnamon Teal |.\/;(/.v< vi/z/o/vc/i/siibspp.]
and .Argentine Rudtlies [Oxyiira viiialci]. suggest-
ing that these are recent arri\ als to South .America,"

For example, Humphrev and Thompson col-
lected se\ eral adull male 11\ ing Sleamer-Diicks m
No\ ember 1979 which had scattered white feath-
ers in the crov\n vvhich ihe\ atlribuietl to a
leucisiicism when, m fact, thes were the lirst few
white feathers of an umecogm/ed supplemental
plumage. It was not until held work in late 19S0
and earh l''8 1 thai we considered the possibility
that Fl\ mg Steamer-Ducks might lia\ c three molts
and plumages per cycle.

.A breakthrough in our uiuleistaiulmg of the
molls and plumages of Atlantic-coastal and iiiegian

STEAMER-DUCKS (ANATIDAE: TACHYERES)

47

Flying Steanier-Diicks lollowcd our organi/alion
of photographs, head pehs. and skins by sex. age
group, and season. We were then able lo determine
that delinitive males go through a elear sequence
of three molls and |ilumages per c\cle. the three
plumages being worn at distinct!) different sea-
sons of the \ear and ha\ ing ver\ difterent aspects.
There is nothing subtle about il: the plumages of
the head and neck of adult male F-I\mg .Steamer-
Ducks from .-Xtlantic coastal Patagonia and L'shuaia
are distmcils different and easily recognizable.
The while-headed supplemenial plumage was
readily explained as being attained by a
presupplemental molt during the austral spring. As
we noted previously (Humphrey and Live/ey
1 982a:6 1, "specimens of atlult male Fl_\ ing Steamer-
Ducks in suppiemental plumage are practically
non-existent in museum ciil lections, which ac-
counts for the statement by Murphy (IM36:^68l
that "the oldest males. ..ha\e clear gra\ heads,
except for the white postocular stripe and the
reddish throat patch." ""

In 1^X2 and 14,X.i we collected a limited series
of T. putcuhouicus in the Andean lakes of Argen-
tina and the southern lakes and coast of Chile and
discovered that the sequence of molts and plum-
ages of adult males from those populations was
not readil) interpretable in terms of what we had
learned from Fuego-Patagonian coastal popula-
tions. Fly ing Steamer-Ducks from the ,-\ndean lakes
of .Argentina and from southern Chile (Region .\)
may have either two or three molts and plumages
of the head and neck per cycle (see discussion of
plumages and molts for T. paiinhonivus beyond).

During Held work in the Falkland Islands, we
collected 20 Falkland Flightless Steamer-Ducks
and were able to obtain specimens of dehniti\e
males representing three distinct plumages of the
head and neck along with hundreds of photo-
graphs of birds in various plumages. During held
work at Puerto Melo (coastal Chubut). we ob-
tained specimens and photographs of 7
Ic'iicdccplhihis that indicate that the species has
only two molts and plumages per cycle. Material
available to us representing the Magellanic Flight-
less Steamer-Duck ( T. ptcucivs ) also suggests that
the species has onl\ two molts and plumages per
cvcle.

In summar\. our current undersiaiKlmg of the
molts and plumages of steamer-ducks is as fol-
low s:

( I ) The Falkland Flightless Steamer-Duck and
coastal Fuego-Palagoman F-l\ing Steamer-Ducks
have three molts and plumages per cycle. We
h\pothesi/e that Fl\ing Steamer-Ducks from the
.Andean lakes of .Argentina and Region .\ of Chile
also have three molts and plumages per cycle but
it is also possible that the\ ha\ e but two.

(2)The White-headed Flightless Steamer-Duck
and the Magellanic Flightless Steamer-Duck each
have two nutlts and plumages per cycle.

(?<) The basic plumage of the head and neck in
both 7". hi\u hxpicnis and T palaclioiucus is sexu-
alh monochromatic and similar to the juvenal
plumage. The definitive basic plumage of the head
and neck of T. leiicoccplialus is sexually dichro-
matic and that of the definitive female is like the
juvenal |ilumage. The plumages of T. piciwixs are
least well known, but basic plumages of both sexes
are similar to the Juvenal, and alternate plumages
are lighter and onl\ weakl_\' sexualK dichromatic.

(4) Dehniti\e plumages are attained during
molt II in Fuego-Patagonian coastal T.
/'(//(/(7)('/)/< i(,vandprobabl\ also in /'. hiiu hxpients.
The detinitise alternate plumage of the head and
neck in male 7". Iciuoccphalus may not be attained
prior to prealternate molt IV or later.

Unfortunately, molts and plumages ha\e been
stLidied for very few species in the tribe Tadornini
(Live/ey l'-)86a). Taclncrcs is exceptional for the
comparatively detailed information on molts and
plumages that is available; virtualK nothing is
known about the molts and plumages of
llximiuilainnis and Mciy,dnctta. genera of po.ssi-
bly close relationship to Tachxcrcx (Livezey
|4S6a). Some species of Tadornini are known to
base two molts and plumages per cycle but we do
not know whether this is consistentK the case for
all species within the tribe. We can oiil\ speculate,
therefore, that the h\pothetical ancestor of
ItH hxcrc\ had two molts aiul plumages per cycle;
the plesiomoi phic stale may be a single molt per
annual cycle. We feel it most unlikely that the
ancestral condition comprised three molts and
plumages per c>cle because of the extreme rarit)
of this pattern in the .Xnalidae. .Assuming that the

48 UNIV. KANSAS MUS. NAT HIST. VlONOCiRAI'II NO. ,S

anccslial sl'(.|lh.mkc oI inojis and pluinaiies liii- per and lower e\i.-lid and distribution ot while in

TacUxcrcs is two molls ami plumages per cycle, tronl of. aho\e. and behind the eye.

then the sequence ot three molts and plumages per 1 he juvenal plumages of the four species of

cvcle evolved independently twice in the genus, steamer-duck are no! sexually dichromatic and are

once in part or all of 7'. ixiUhliiiiiii lis and once in virtually identical among the four described spe-

r. hracliyplciiis. assuming that the phylogenetic cies. Head and neck of all four species in juvenal

hypothesis of Live/ey ( I'^ASdc) and Corbin ci ul. plumage are unicolor dark brown or dusky gray

(I9SS) for the species of Tcichycrcs is correct. v^ith the crov^n slightly darker anti an indistinct

Alternatively, the three-plumaged condition may chestnut patch on the throat. Juveniles of T.

have evolved in ancestral Tcichycrcs. was retained paniclKiniciis and 7'. Iiracliyplcriis have very faint,

in T. pahicluiiiK lis and 7. hnicliyplcnis. and the narrow, mdistinct whitish postocular streaks. Be-

suppleniental plumage secondarily lost indepen- cause of their great similarity, we Judge that juve-

dently in both 7' Iciicoccplniliis and 7' picncrcs. niles of the four species would be impossible to

We have been unable to identify life-historical, distinguish in the tiekl.

behavioral, or environmental characteristics held Our data on predetinitive plumages in all four

\nc(immonby'I\ paiiicliDnlciisundrhriicliyplcriLs species of steamer-duck are meager and difticult

that distinguish both of those species from 7". to interpret. Baseil on the si/e of the bursa of

Iciicoccpluiliis and 7'. ptciicrc.s and account for the Fabricius. we judge that the majority of detinitive

(possibly independent) evolution of the se(.|uence plumages in all species of steamer-duck are at-

of three molts and plumages per cycle in the lained b\ moll II. A possible exception is the

former. Nevertheless, in 7. piiun Imiiicus and I', detinitive alternale plumage of male T.

/wv/r/n/ncyz/.v. the sec|ueiice. timing, and aspects of Iciicoccplialii.s which ma\ be attained by

plumages are virtually identical and the two spe- prealternate moll IV.
cies cannot be reliably distinguished in the lield

where they co-occur in the Falkland Islands. T ifiivmr^ n\T\riii)\i(ii'i

We have examined specimens of dt)wny young

of the four recognized species of steamer-duck Humphrey and Live/ey (m82a) published an

(Humphrey and Live/ey 1985). The specimen of account of the molls and plumages of Flying

the Flying Steamer-Duck (age class 1) examineil Steamer-Ducks based principally on fresh, sexed

was from Chilean Tierra del Fuego and collecletl specimens with information concerning condition

by G. Watson (LISNM 485600). Additional speci- or absence of the bursa of Fabricius. In that study

mens of class-1 downy Flying Steamer-Duck col- we concluded that Flying Steamer-Ducks have

lecled by M. W. Weller in the Falkland Islands three molts and plumages percNcIc and that delini-

were examined subsequeni to our 1985 jniblica- ii\e plumages may be attained starting with the

lion. From the meager specimens ami data a\ail second prebasic molt when birds arc about one

able, we cannol determine whether there is any year of age.

significant geographic variation in patterns or as- Subsequent to the completion of our 1 982 study

peel of class-1 downy Flying Sleamer-Duck. We we learned that Flying Steamer-Ducks exhibit

ha\e not examined class-1 downy specimens of 7 considerable geographic \ariation. Our early de-

/)(//(/( /((j/»(//.v from populations breeding on moun scriptions of plumages of Flying Steamer-Ducks

tain lakes of Argentina or Chile. ma\ iiol appK in detail to freshwater populations

The plumage of very \oung (age class I ) downy m Chile (Region .\). the .Andean lakes of .Argen-
stcamer-ducks is the oiil_\ iilumage which is abso- una. .iiul the Falkland Islands. I inforlunately.
lutely diagnostic for each of the four species ol samples of fulh ilocumented specimens of Flying
steamer-duck. The diagnosiic differences among Sieamer-Ducks (including data on sex. gonad
the four species in the class-I downy plumage measurements, coiuiition of bursa of Fabricius)
consist principally of variations in the paltern of from these |iopulalions are inadequate to inierprel
the lieail. comiirising specilicall\ color ol the up- then sequences ol molls and plumages. Our I 1982)

Di;H\ITIVE Pi l^MACiKS OF Malhs

Basic Plimiace

STEAMER-DLICKS(ANAT1DAE: TM'lDl-KES) 49

dcsLTi|itioii.s (it tliL' nuilis aiul pluniauL's ot Flyniy worn lor appi()\inialcl\ nine nionllis. I'hc tlctini-

SleaniLM-Ducks lluis appl\ in dclail oiil\ to iiianin.- li\ c Mipiileniental pkiiiiagc ol the head and neck is

coastal populations liom soulhein I'atajjonia and strongly scMuilly dimorphic and is worn lekilively

Tierra del Fiiego. brietly.

The sequence ol molls and plumages of adult The lollowmg descri|itioiis apply to marine

male Atlantic coastal and Fuegian Hying Steamer- coastal populations Irom Patagonia and Tierra del

Ducks comprises (Fig. '-)): (1) a prebasic moll Fuego and include, when possible, notes on plum-

which lesulis in a bnelh-worn |ii\ enal-like ilark ages ot'other populations, all ol which we assume

head and neck and which also replaces remiges. but cannot demonstrate to have three molts and

rectrices. and the entire leather ctuit of the bods ; iilumages per cycle. Flying Steamer-Ducks prob-

(2) a prealternate molt during the growth of new ably attain tlelinitive plumages with the second

remiges which results in a head with dark cap. prebasic molt when they arc about one year old.
brown cheeks, and white postocular streak, worn
about nine months uniil mid or late spring; and {?>)
a presupplemental molt which results in a pre-
dominantly white head and neck wurn for one or
two months from mul to late spring until the early
austral summer. Thus, except for leathers of the Hccniiiiul neck. — Vary from brown, dark brown,

head and neck which are replaceil three times a to dark purplish gray with crown slightly darker

cycle, the body feathers of adult Flying Steamer- and posterior cheeks and side of neck slightly

Ducks appear to be replaced but once per cycle by lighter in some specimens; variation (termed

means of a prebasic molt which usually occurs "phases" by Humphrey and Livezey m82(/)isnot

during a relatively brief time in the austral summer. age-related. Throat dark cinnamon bordered later-

The same seciuenee of molts and plumages is ally by medium to dark gray. Some specimens

also true for adult females in which: ( 1 ) the basic have a very short trace of a whitish postocular

plumage of the heail and neck is dark and almost streak.

unicolor; (2) the alternate plumage comprises a Linvcrhrcu.st.hcIlx.iiiklcrrui/cDVcrts. — White,

dark gray cap. white postocular streak, and dark Upper hack. — Fresh feathers medium gray with

brown cheeks; and (.^) the supplemental plumage narrow dark gray margins anteriorly becoming

of the head and neck has a dark brown cap. dark browner (dusky brown) more posteriorly as the

reddish-brown cheeks and has no postocular streak feathers become more extensively light silvery

or only a very slight one. gr^y-

Adult females from coastal Patagonia aiulTierra Scapulars. — Light silvery gray broadly mar-
del Fuego appear to undergo the presupplemental gined with sepia.

molt somewhat earlier than males. In addition. Lower Innk. ruiup. i/iiJ upper tail (dvert.s. —

from the small sample available to us. the Medium to dark gray; leathers with taintly darker

presupplemental molt in adult males from Tierra margins.

del Fuego may occui as much as a month later than Upper hraisi and .sides. — Fresh upper breast

in Puerto Deseado. leathers cinnamon becoming slightly more red-

In. Atlantic-coastal aiul Fuegian Fly ing Steamer- dish distalK and broadh tipped with blackish
Ducks of both sexes the tielimtive basic plumage brown with a subteiniiiKil patch of light sihery
of the head and neck is acquired immediately prior gray. Laterally, the leathers are less cinnamon and
to and tiiiring the onset of the prebasic molt of the medium grav until on the upper sides there is no
w ing and closely resembles the luvenal plumage. cinnamon. .Also the more anterior upper breast
This is replaced during prebasic molt of the wings leathers are darker cinnamon. There is consider-
by the alternate plumage of the head and neck able indivitlual \ariation in the extent and shade of
which exhibits moderate sexual dichromatism. cinnamon on leathers of ihe upper breast and
differs in aspect from Ihe juxenal plumage, and is upper sides and in the disti ibuiion of leathers w ith

50

UNIV. KANSAS MUS. NAT. HIST. MONOdKAI'll NO. X

ciniianmn b;iscs. .Some iiuli\ ulii;ils lia\c \l'I"\ lilllc
cinnamon on the bases ot the upper breast leathers.
This variation is not clue to wear and lading: ue
have no evidence that tliere is more than one moh
of upper breast anil sides per cycle.

.S'/</t'.v and Jlaiik.\. — Light silvery gray, leathers
with wide chestnut margins. Margins ot worn
feathers become narrow and brownish olive and
eventually fade to buffy brown with much nar-
rower tips. We could detect no differences among
males from the Faiklands, Atlantic coast of
Patagonia, Tierra del Fuego. the Argentine lakes,
and the lakes of Region X, Chile, in appearance of
fresh dclinilive basic sides and Hanks.

supplemental plumage o\ the head anil neck that
comprises either: (a) gray cap. reddish cheeks, and
long white postocular streak, or (b) head and neck
entirely white (as in coastal Palagonian and Iniegian
birds). Wc have collected no specimens of birds in
this latter plumage (.^b) in the .Andean lakes of
Argentina and Region X. Chile.

We tentatively conclude that it is most likely
that Chilean and Andean males have three molts
and plumages (hypothesis 2) and that we have
neither seen nor collected binls in uhat we pre-
sume to be alternate |ilumage. Possibls the alter-
nate and supplemental plumages are indistinguish-
able.

Alternate Plumage

As far as we can determine, only the feathering
of the head and neck is replaced during the
prealternate molt.

Head and neck. — Crouii medium to dark gray;
lores and cheeks medium dull grayish-brown; long
white postocular streak partly occluded in auricu-
lar region: throat medium cinnamon.

The limited series of specimens available to us
from the Andean lakes of Argentina and the lakes
and coasts of Region X, Chile, does not enable us
to demonstrate conclusively that adult males in
these populations have three molts and plumages
on the head and neck per cycle. From the material
available we can formulate two hypotheses con-
cerning the sequence of molts and plumages of the
head and neck of Flying Steamer-Ducks from the
Andean Lake District of .'Xrgentina and Region .\,
Chile:

Hypothesis 1 : Adult males have but two plum-
ages of the head and neck per cycle comprising ( 1 )
an all dark basic plumage and (2) an alternate
|ilumage comprising gray cap, reddish cheeks, and
long white postocular streak, similar to the alici-
nalc plumage of coastal populations liom souihcm
Patagonia and Tierra del luego. fins hypolhesis
|H)stulates the lack ol a Mip|ilemcnlal plumage.

Hypothesis 2: Adult males lia\e three plumages
of the head and neck per cycle comprising ( 1 ) an
all dark basic plumage: (2) an hxpothctical ;illci
nale plumage comprising gray cap. icddish checks,
and white postocular sircak: .iiul ( i) a dehiiiiivc

.Suiiplemenial Plumage

As far as we can determine, onl\ ihe feathering
of the head and neck is replaced during the
prcsupplemental molt.

Head and neck. — White w itli pale gray wash on
cheeks, ilarker on lores; throat medium cinnamon
bordered w ith pale gray. The amount and distribu-
tion of gray on the head and neck of coastal
Patagonian and Fuegian males \aries consider-
ably from: ( I i cap, cheeks, and lores light brown-
ish-gray; to (2) head and upper neck light or
medium gray with a slioii. ikuiow \\ hite postocular
streak. Some individuals ma\ ha\e completely
white head and neck except lor ,i cinn.unon patch
on the throat.

ll IS possible that the delmitisc supplemental
plumage of ihe head and neck of males from the
Andean hikes of Argentina and Region \. Chile
also is while, but we ha\e no specimens to docu-
ment this.'fhe lew specimens of adult males avail-
able to us ( bursa of lahncius \ estigial or lacking)
starling |ircbasic moll ol the head and neck have
medium gras cap and nape, forehead slightly lighter
and nape slightl\ darker; lores ami cheeks light
lusciuis with lainl smoke-gra\ tips, becoming
giaser and slighil\ lighter jiosleriorls. The base of
the neck Is w hite, the chin is light medium brown-
ish-gia\. and ilic lliro.il mediiim icililisli clicsiuut.
I here is a pioiiiincnl white postocular streak.

A highl\ \M)m .laiui.iix specimen (KU 798.S4)
from near Piiciio \loiiii. Chile, had laded head and
neck w itli new d.iik basic ieailieiscomine in on the

STtAMER-DUCKS (ANATIDAE: TACHYERES)

51

loivhcad. The ltowii and nape ol tins bud were
faded gra> and the clieeks anti lores light gra\ with
posieric>r cheeks and base of the neck white. The
hnver cheek was slightly darker and the throat was
niediiuii reddish chestiuit. In the bright sun this
bud woiikl look white-headed in the held.

It IS possible that the supplenienlal plumage of
the head ami neck ol atlult males from the Andean
lakes of Argentina and the southern lakes of Chile
becomes increasingly white in older birds. How-
ever, there is stronger evidence to suggest that, if
these populations have three molls and pkimages
percycle. the detmitive supplemental plumage has
gra\ cap. fuscous cheeks and a prommenl white
postocular streak, and resembles the alternate plum-
age of coastal birds from southern Patagonia and
Tierra del Fuego.

DKFtMTivE Plumages of Femai.e.s

streak occluded postei"ioil\ b\ incthiim bro\Mi
becoming a whitish patch on sitles of neck: throat
dark cinnamon, neck medium brown with paler,
almost whitish collar.

Supplemental Plumage

//(■(/(/ (iihl link. — Crown medium gray with
brownish cast to dark grayish-brown; lores and
cheeks fuscous chestnut to dark reddish brown,
grading to dark grayish brown and then darkish
metlium gray on the neck; throat medium chestnut.
Ihe white postocular streak is short. While similar
to the alternate, the supplemental plumage differs
in lacking the white collar, and in having a very
short postocular streak and ;i pronounced reddish
cast 111 the lores.

Predei-imtim-. Piamage.s
(Both St \es)

Basic Plumage

Ih'ihl iiihl iiciL. — Dark chocolate brown; cap
darker in some individuals; neck medium brown
in some individuals; throat dark cinnamon; eye
lids white; white postocular streak short or (possi-
bly) absent.

Lower hic'iiM. helix . iiihlci mil cavcrts — White.

Upper hack. — As in definitive w liite male ex-
cept that feather margins are sepia to brownish-
olive and wider.

Lower hack, ritnip. and upper tail covens. —
Dark gray; feathers of the low er back and rump are
faintly silvery and have narrow, indistinctly darker
edges.

Upper hreasi and sides. — As in definitive male.

Sides and jlanks. — Slightly darker than those ot
detmitive males, although the ililference is not a
reliable character lor determining sex. Sides ap-
pear to be replaced only once per cycle. The hrst
basic siiles and thinks are identical with those ol
sLibsc(.|uent basic plumages except the chestnut
margins appear to be slightly narrower.

Alternate Plumage

Head and neik. — Forehead and crown dark
gray; lores and cheeks dark brow n; white postocular

Juvenal Plumage

The following account ilescribcs a specimen
(KU 7M2I1), one of two males collectcti on 20
.lanuarv l^'SI at Puerto Deseado from a family
group of five juveniles accompanied by a pair of
ailults; the two males collected were identical in
aspect. Although we have examined no lemales in
juvenal plumage we presume thev are identical in
aspect to males of similar age.

Head and neck. — Dark brown, crown slightly
darker, patch on throat chestiuit. Upper and lower
eyelids white; narrow, ill-dehned pale buffy
postocular streak extending the length of the cheek.

Lower hreast. helix . umlcr unl coverls. — White.

Upper haik. — Feathers silvery gray with dark,
almost blackish gray margins, giving a scalloped
effect.

Scapulars. — Silvery gray with tiarker blackish
margins.

Lower hack. rump, and upper tail coverts. —
Medium gray.

Upper hreasi and sides. — f-eathers pale silvery
grav with dark almost blackish gray margins. No
chestnut at the bases of any of the feathers of the
upper breast and sides except for the last rows of
feathers just before white leatliers of the upper
breast.

52 UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. S

^444

Scd sS sy <

u. a. u- H U-cyj Z

tup UJ_1 iu< ul

Qc/n Q < Qoa >

1-1 ?

O O

STEAMER-DUCKS (ANATIDAE: TACHYERES) 53

<

5S:i Zg ZJ

u-v: u. [- Eg"

Qco Q< S;^

o o o

-'•'3

54

UNIV. KANSAS MUS. NAT.

LSI. MONOCIRAPII NO. S

.S'/(/<'.s iiiul lliiiiks. — Fe;ithers silvery gr;iy v\ itli
blackisli eia> margins; the tlank feathers are nie-
diiiin gray v\ ith very narri)\v. washed out brownish
or chesliuii margins.

Downy Plumage

The following description is based on three
specimens from Chile: USNM 4S56()() (class-l,
female, 1 February 1964), FMNH 120521 (class-
II. female, 28 January 1940), FMNH 1 20?22(class-
II, 28 January 1940).

Head and neck. — Upper eyelid dark biownish
oli\e; lower eyelid whitish. Cheeks, lores, lore-
head, crown and nape dark brownish olive.
Supraocular and supraloral patches are whitish
and very narrow, becoming even narrower anteri-
orly: they are widely separated from the postocular
streak which is broad and whitish.

Upperparts. — Yoke light fuscous; lower back
and rump dark brownish-olive.

Undcrparts. — Upperbreast brow nish-oli\e;
lower breast and belly white.

Taciiyfrks hrxchyptervs

Series of specimens of the Falkland Flightless
Steamer-Duck collected in Februar\ 19S4 tlemon-
strate conclusivels that this species, like the Fly-
ing Steamer-Duck, has three molts and plumages
per cycle (Fig. 9). Detiniti\e plumages of both
sexes are indistinguishable from those of Atlantic
Coastal and Falkland populations of the Fl\ing
Steamer-Duck anil seasonal occurrence of the three
dclniiti\e plumages appears to be appro\imatel\
the same in the two species. Our understanding of
aspects and timing of predelinilive plumages is
\ers liiuned. but we suspect that (.lelinitive pliuii
aees are attameil duruii: molt II.

neck; narrow, rather short white postocular streak.
Chin medium dusky brown: throat chestnut. Fore-
head dark chestnut mi.xed with light gray feathers;
crown chestnut, darker on the nape.

The prebasic molt of the head and neck has just
begun in an adult male (KU 80.52.5) collected on 14
Februar\ 1984; the specimen had no bursa of
labricuis. In this specimen ilark blackish brown
feathers are replacing the supplemental w hiie feath-
ers of the forehead, lores, and anterior cheeks. Two
adult males (KU 80515 and KU 80520) collected
on 9 and 10 February (neither with bursa of Fab-
licius) are in lull basic plumage of the head and
neck except for the crown, which is molting into
the light to medium gray ot the alternate plumage.

Lower hrcasr. helix, under tail coverts. — White.

Upper hack. — Feathers medium gra\. the more
posterior ones with broad blackish brown margins
and a silvery gray wash.

Scapulars. — Sihery gra_\ with broad, dark
chestnut margins.

Lower hack. rump, and upper tail coverts. —
Medium gra\ becoming somew hat lighter posteri-
orly.

Upper hreasi and sides. — Upper breast dark
brovM) with faint margins of pale gravish. The
indi\ idual leathers are metlium chestnut w ith broad
dark brown terminal banil and. in the more poste-
rior leathers, a narrow subtermiiKil baiiil ol pale
gray. With wear the upperbreast becomes increas-
ingly chestnut in appearance. The leathers of the
sides are silvery gray with wide blackish brown
margins.

.V/(/c,s <nid flanks. — Feathers light gi,i\ w ithdark
brown margins which become w uler ;iiul d;uk
chestnut in the long flank leathers.

Reini'.;es luiil redrices. — Blackish blown with
\;ir\ing amounis of sihers gra\ on then dorsal
surfaces.

Di I iMii\ I I'l I \i \(.i s Ol Malks
Basic Plumage

Head and neck. — Lores dusky brown, grading
to dark chestnut posteriorly, medium chestnut on

.Alternate Plumage

•As far as we can determine. onl\ the leathering
of the head ami neck is replaccti during the
prealternate molt.

Head and neck. — Crown medium 'jra\; lores

the cheeks and slightly lighter on the sides of the dusky brown becoming medium gra\ posieriorls:
neck. gr;iyish more postenoil> ami on the hiiul cheeks dullish brow n becoming somew hal lighter

STEAMER-DUCKS (ANATIDAE: TACHYERES)

55

aiul izruNCi" iiosienorlN. Hiiui neck and sides of
neck pale to light gray, darker and more brownish
in some individuals. Chin medium gray, throat and
\eniral neek chestnut. Long, white posiocular
streak, more prominent in some individuals than
others. One specimen (KU 80517) is in hea\ y
prealternate molt of the head and neck and ni \ ery
heavy prebasic molt of the body; the old worn
remiges were still firmly attached. Prealternate
molt of the head and neck may occur as late as
February and as early as October or November.
Color slides provided us by O. S. Pettingill. Jr.. M.
W. Weller. and T. Narosky show bright-billed,
presumably definitive birds in alternate plumage
in November. December, and January. We photo-
graphed and collected definitive males in alternate
plumage in Januar\ and February.

Supplemental Plumage

//(■(/(/ (///(/ iici k. — The definiti\ e supplemental
plumage of males has the throat mednim to dark
chestnut and the rest of the head white. It appears
that some individuals have completely white
crowns and napes. vUiile others have crown and
nape pale to medium gray. We have seen no speci-
mens in presupplemental molt or in fresh detini-
tive supplemental plumage of the head and neck.
All specimens we have examined are in worn
supplemental plumage with the head and neck
predomniantls white except for dark incoming
basic feathers in the lores, forehead, anterior crow n
and anterior cheeks. We ha\e examined specimens
and plK)togra|ihs of definiti\e males with \arying
amounts ot white supplemental plumage on the
head and neck indicating that the presupplemental
molt may start as early as October and as late as
December or January.

DiiiMiiM PiA viaCjES of Females

Basic Plumage

Comparison of specimens show s that, except for
plumages of the head and neck, the basic plumages
of detinitne males and females are identical.

Hcciil and ncik. — The heads and necks of four
females without bursa of Fabricius collected in

I-ebruary all appear to be mostls in tlelimtne basic
plumage with varying amounts ot new alternate
plumage. All four specimens (KU 80516. KU
805.^2. KU 805 1 3. KU 805 1 8 ) have fresh, unw orn.
new remiges. In these four specimens the lores and
anterior cheeks are dusky to blackish brown be-
ciiming chestnut more posteriorly. The forehead,
crown, nape and hind neck are dusky brown be-
coming lighter and somewhat grayer posteriorly.
The throat and ventral neck are dark chestnut. The
eyelids are white and some individuals have a very
short white postocular streak.

.Alternate Plumage

lUiiil uiul neck. — We ha\e not examined any
specimens in full alternate plumage of the head
and neck. Photographs indicate that the definitive
alternate plumage of the head and neck of temales
is similar in aspect to that of the Atlantic-coastal
populations of Flying Steamer-Duck. The crown
IS medium to dark gray; lores and cheeks medium
dull grayish-brown; long white postocular streak;
throat chestnut.

Supplemental Plumage
Hciid and neck. — LInknown.

Predefinitive Pllimac.es
(Both Sexes)

Juvenal Plumage

Slides taken by T. Narosky in December 1978
(file no. 2692) and February 1078 (file no. 2685) at
Port Stanley show two indi\ itiuals in lull juvenal
plumage. The remiges on both individuals in each
photograph are partially grown in that the white
secondaries are barely visible be> oiul theirco\ erts
and the tips of the primaries are not e\ idem. We
assume that, as in other species of steamer-duck,
there is no sexual dichromatism of the juvenal
plumage in this species.

Head and neck. — Unicolor dark brow n; upper
and lower e\elids white; narrow, pale bufl\
postocular streak extends lor about a centimeter
posterior to the eye and then becomes broader

36 UNIV. KANSAS MLIS. NAI . HISI. MONOGRAPH NO. 8

and \ciy taiiil. luixIiil; vcnlrall) posiciioi to ihe species ol stcanicr-duck. the pivallcriiatc iiioll ap-

chcek. parenlly iinoKes onh feathers of the heaii and

Lower breast, belly. Kiiclcr tail coverts. — White, nock (Fig. 9). We have found no evidence that

Upper back. — Feathers medium gray with dusky leathers of other pterylae are replaced more than

brown margins. once per cycle.

.Scapulars. — Medium gray, broadly margined Tlie definitive basic plumage of the head and neck

with dusky brown. of male T. pieneres does not resemble the juvenal

Loner hack. rump, ami upper tail coverts. — plumage. Thus there is sexual dichromatism of the
Medium gray, each leather with narrow diisk\ detinitive basic plumages of the Magellanic Flight-
brown margin. less Steamer-Duck: the females have dehnitive ba-

Upper breast and siJes. — While the ventral sic plumage of the head and neck unicolor mediinii

upper breast is not visible in the photographs, the gray whereas the definitive basic plumage of the

feathers of the sides of the upper breast are me- head and neck of males has a meelium gray cap and

diuni gra\, broadK margined with dusky brown. lores, light gray cheeks and neck, and pale gray to

Sules ami Jlaiiks. — Feathers medium gra> w ith w hitish. rather short postocular streak. The Magel-

broadduskv brown margins. In one indivitlual. the lanic Flightless Steamer-Duck is unique in the genus

elongate Hank feathers are light to medium ilusks m that the detinilne basic plumages of the head and

brown w ith darker margins. neck of neither se,\ resemble the |u\ enal plumage.

We have examined specimens of male Magel-

Dowii\ Plunri"e lanic Flightless Steamer-Ducks in detinitive alter-
nate plumage collected in November. December.

The following description is based on live and January, many of them in the early stages of

unsexed. class-I specimens from the Falkland Is- prebasic molt of the head and neck. In addition, we

lands: AMNH 419160 (7 December ]^\5). MCZ haveexammed four specimens from thcXmerican

70.^21 (15 December 191.5), MCZ 70522 (figured Museum of Natural History, collected by Beck

inMurphy 1936), BM 19.^0. 12. IS. 1. BM (nonum- near C'hiloe Island, also in tlelinitise alternate

ber, 29 November 19,^61. plumage of the head and neck. We have seen two

Headamlncck. — Llppereyelid medium tuscous: specimens (taken m December and .lanuary ) in
lowereyclid whitish lopale fuscous. Cheeks, lores, definitive basic plumage of the head and neck,
forehead, crown, and nape medium fuscous. The Nine additional specimens (taken during .April-
very pale(almost whitish)smoke gray supraocular July) are in definitive basic plumage of the head
ami sLipialoral patches are uninterrupted, very nar- and neck anil one ot them (.AMNII 44.^670) still m
row and even narrower at the junctions of the prebasic molt ot the head and neck,
supraloral and supraocular patches and the From the limited data at ouidis|iosal. we specu-
supraoculai patch aiul postocular streak. The \ en- late that (he majoritv of adult male Magellanic
tral margin of the su])raocular patch abo\e the Flightless Steamer-Duck are in alternate plumage
uppereyelid is dark dusky brown. The supraocular o| ihe heatl ami neck during the late spring and
patch is coniiiuious wiih llic posi<Kulai streak summer ami wear the basic plumage of the head
which is very pale smoke gray and contmuous. and neck during the balance of the year for perhaps

I'pperparrs. — Yoke light fuscous: lower back ,s to 10 months. .Assuming a relationship between

ami rump iiicdium to dark fuscous. the occurrence of the (.lelimtne alternate plumage

Uiulcrparis. — LIpper breast fuscous: lower m niales ami nesting, the occurrence of four males

breast and belly white. collectetl in May in i.leliniti\e alternate plumage of

(he heailami neck woukl indicaie (hat a( least some
Magellanic Flightless Sieamer-L^uck nest during
the austral winter: this Wdulil appear to be espe-

The Magelhimc Flightless Steamer Duck has ciall\ likely in the lower latitudes around Chiloe

two molts and plumages per cycle. .As m all other Maml :iiid larthei to the north.

'/' \( IIYI Urs rilSERES

STEAMER-DUCKS (ANATIl:)AH: I .H'II)I:RFS)

57

Dhl-IMIIVH Pi UMAClhS Ol- MALI'S

B;isic ['kiinage

//(■</</ aiul neck. — An adult male (AMNH
443707) collected on 3 1 July in the Beagle Chan-
nel is in tVesh plumage, wings unworn and appai-
ently quite new. Forehead, crown, and lores me-
dium to darkish gray becoming darker anteriorly.
Feathers of forehead and crown with narrow dark
chestnut shaft streaks. Nape medium gray becom-
ing lighter on dorsal neck. Cheeks light gray be-
coming darker anteriorly and broadly mottled
darker elsewhere. Chin medium gray. Indistinct,
diffuse, light-medium cliestnut thumb-sized throat
patch. Neck light gray, d.ii ker dorsally. Indistinct,
pale gray (mottled slighil\ tlarker) postocidar
streak.

An adult male ( LLSNM .'S.i6.i4S) collected on 24
April in Argentine Tierra del Fuego has crow n and
lores medium gray, forehead slightly paler, ante-
rior cheeks light-medium gray becoming paler
posteriorly and grading into light gray in the neck.
Chin light to medium gray becoming paler poste-
riorly. Throat faintly brownish gray, grading into
light gray on the ventral neck. No leathers on the
head and neck were molting.

Liwcr hiCiist . hcU\. ii/ulcr iiiiUdvcris. — While.

Upper hack. — Feathers dark gray, the more
posterior ones with a patch of light silvery gray
along the rachis.

Scapulars. — Feathers dark gray with patch ol
light silver> gray along the rachis.

Lower hack, niiiip. and upper lail cti\'erl.\. —
Feathers medium to (.lark gray with slightly darker
margins.

Upper hreasi and \ides. — Feathers of the upper
breast are banded with a \ cry narrow pale slightly
worn smoky gray tip; a subterminal band that is
blackish-brown and is broader anteriorly and nar-
rower posteriorly; the next band is variable in
shape and size and color, being cinnamon in more
anterior feathers and becoming faded cinnamon
posteriorly and hnally becoming medium gray in
the more posterior and lateral feathers including
those of the upper sides.

Sides and flanks. — Feathers light silvery-gray
with medium blackish-brown margins. .Sides and

Hanks are moderately worn in a specimen t;iken in
November and the dark margins, especially ante-
riorly, are narrower and the feather tips fra\ed and
light smoke gray.

l\c})U'^e\ and rectrices. — Black or blackish-
brown with varying amounts of silverv-grav on
their dorsal surfaces.

Alternate Plumage

llciul iiuil neck. — An adult inale (AMNH
44.Vi(iM) collected on 19 May at Chiloe Island has
crown and lores light gray becoming slightly darker
anteriorly; cheeks pale gray becoming whitish
posteriorly. White postocular streak present, and
chin pale gray. Throat with very small patch of
pale chestnut becoming paler and grayish/whitish
at its margins. Neck pale gray dorsally grading to
w hitish ventrally. Other adult male specimens in
alternate plumage of the head and neck from Chiloe
Island are AMNH 443661 (12 May) and AMNH
443671 ( IM May).

In addition, an adult male (AMNH 733418)
collected on 27 Novemberat Frutillar(near Puerto
Monti) Chile was in quite wurn pluiTTage with old,
frayed wings. The head and neck appear to be in
worn alternate plumage. The forehead is light faintly
huffy gray becoming darker on the crown which is
medium gray. The lores are medium gray. Cheeks
light smoky gray becoming whitish posteriorly.
Chin pale smoky gray. Throat with diffuse light-
medium chestnut patch. Neck worn and whitish.

The definitive alternate plumage of males is.
except for light gray crown, brownish-gray lores
and pale gray neck, all white with an indistinct
patch of pale cinnamon on the throat. A November
specimen from Tierra del Fuego (KU 77969) and
a December Chilean bird (KU 79S42) are in this
gray-capped alternate plumage in which the rest of
the head and neck is white.

Di iiMiivi; Pi.iiMACiKS or F[;mali-:s

Basic Plumage

Comparison of series of s|iecimens of definitive
males and lemales at the American Museum of
Natural llistoi\ rc\cals iluit. other than the head

58

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

anil neck, iho tlcliriili\e basic plumaucs ol'llic luo
sc.xcs arc itlcnlical.

//(■(/(/ anil neck. — Forehead, crown, and lores
mciiuMii darkish gray, feathers of forehead with
tainl. paler margins ( from wear and fading). Cheeks
medium gray or medium smoke gray becoming
darker anteriorly. Chin and neck medium gray.
Iiulisimci ihunib-si/cd patch of medium chestnut
on Ihroal. l-aml, ill-detined. short poslocular streak
light gray, mottled liarker.

Examination ot specimens taken during De-
cember (KLl 798.V^) and November (KU 77967)
indicateil that the detinitive basic head and neck is
unicolorgray with no white or whitish postocular
streak. The first specmien had dropped its remiges
and was in heavy prehasic molt of the head which
was about three-c|uarters complete. The second
s]iecimen was in high basic plumage of the head
and neck and is starting the prealternate moll; of
particular note m the specimen are the obviously
grow ing. white postocular feathers.

Alternate l^lumage

Head (111(1 lu'ik. — Crown and forehead dark
gra_\. becoming paler on the nape: lores dark gra\
becoming meilium gray on cheeks and fading to
light gray and then pale gray — almost whitish — at
base of neck. Short |iale gra\ to whitish postocLilar
streak. Chin medium gra\ ; throat varies trom small-
ish patch of pale cinnamon or reddish brow n to a
more extensive patch of ilull chestnut. Wear aiul
lading may account tor some of this \ ariation. ( )ne
December bird (Kf 79S,V)) was beginning
prealternate moll of the head and neck and aheatly
had a pale gray postocular streak.

Pri:iii-;ii\iii\i Pi i \i \(.i;.s
(Bnm .Si \i si

.Alternate I'lumage

//(■(/(/ (iiul iifi k— \\\o males ciillected m No-
vember hail crow n. lorehcail. nape, lores, aiul chin
medium gray. Cheeks light gray. Throat faintl>
marked pale cinnamon. The extent and strength ol
the cinnamon on the throat \ aries from practicalls
indiscernible lo a ilisimcl pale patch.

Jmenal I^lumage

Examination of nine specimens of Magellanic
F-'lightless Steamer-Duck in full jiivenal plumage,
collected at \arious localities in March. April.
May, and July, revealed that males and females are
identical in this plumage. Observations by N. and
J. Goodall (pers. comm.) indicate that the pre-
juvenal molt in I . ptcncrcs may not begin uiiiil the
young birds exceed 60 days of age. It is not known
iiow long the juvenai plumage is worn nor the age
at which the first prehasic molt begins. From the
ten specimens (one unsexed) at hand we suspect
that the onset of the Hrst prehasic molt in Magel-
lanic l-lighlless Steamer-Ducks is much delayed
compared to most other tadornine and anatine
waterfowl.

Head aihl neck. — Forehead, crown, nape, lores
dark (purplish) gray: neck medium dusky gray,
lighter ventrall\. Cheeks medium lo darkish dusky
gray becoming dark anteriorly and in the lores.
Chin medium dusky gray. Thumb-si/ed patch of
medium brovsnish chestnut on throat.

Lower hieasl .helly.undeiiail Cdveris. — White.

Upper hack. — Medium dusky gra\ish-brown.
Posteriorlv the leathers ha\e tlark duskx -briiw n
margins gi\'ing a faintl\ scalloped appearance.

Scapniars. — Medium gray ish-brow n w ilh dark
ilusks-brow n margins.

Loner liack. rump, and upper tail covets. —
Medium to dark grayish or dusky brown.

Upper hreasi and sides. — Feathers mcilium
dusk\' gra\. more or less hea\ il\ tippetl tiark hlack-
ish-brow n becoming less hea\ il\ marked on up]ier
siilesand paleraiul lessdisiinct posteriori). Feather
bases are pale smoky gray.

Sides and flanks. — Medium dusk\ brow ii. leaih-
ers liarker low aid tips ami becoming slightls brow n-
ish posteriori). Some leathers ot sides wiih faint
traces of pearl\ gra\ along distal rachis.

R(-nii'..;es and rectrices. — Blackish brown with
slight wash of siKery gra\ on dorsal surlace near
rachis. i'rimaries ami greater upjier priniarv co-
\erlsdaik dusk\ brown with blackish brown shafts.
Secondaries white. .Axillaries and central part of
wing lining white; b;ilance of umler wing coserts
mediuiii dusk\ hiciwii. the giwiler umler primary
co\cils p;ilci. ketnces medium bfickish-brow n

STEAMER-DUCKS (ANATIDAH: lACIDERES)

59

with bkick sliall ;ind vei'_\ laml mesial wash ol
silvery gray.

Dow n\ Pliiiiiaye

The IoIIowihl; (.lescri|ilmii is based on eight
class-I specimens troni Chile: AMNH 443684
(male. 3 December IMI4i. AMNH 443683 (male.
4 December 1914). AMNH 443687 (female. IM
Jaiuiary 141?). AMNH 443689 (male. 30 Novem-
ber 1914). AMNH 443704. 44370.3. 443706.
443708 (3 males. 1 female. 11 January 191.3).

Ilcuilancl neck. — LI pper eyelid blackish-brown;
lower eyelid whitish. Cheeks, lores, forehead,
crown, and nape dark brownish-olive becoming
lighter on the anterior forehead. Supraloral patch
very small or absent; supraocular region blackish
brown except for a whitish patch which may be
absent, faint, or small but when present is always
separated from the postocular patch and from the
supraloral patch when it is present. Postocular
streak whitish and di\ ided into separate anterior
and posterior parts.

Vppciparts. — Yoke medium brownish-olive;
rest of upper parts dark brownish-olive.

Viulcrpaits. — LIpper breast brownish-olive;
lower breast and belly white.

Tachyeres levcocephalvs

In theirdescription o\ Tlk hxcre.s leindccphalus.
Humphrey and Thompson (1981:8) stated that
"from examination of specimens and photographs
of T. leiicocepluiliis. we judge that adult birds of
both sexes go through a complete prebasic moll in
summer (February), shedding the remiges simul-
taneously and then without interruption undergo a
partial molt involving the head and neck and pos-
sibly other parts of the body. Adult males collected
in September were white-headed as were those
with worn wings collected in February before they
had initiated the prebasic molt. The limited data at
our disposal suggest that either adult males wear a
white alternate plumage of the head and neck most
of the year or that, if there is a supplemental
plumage, it too is white. ..we tentatively assume a
two plumage cycle since we have no evidence to
the contrarv.""

■Since that was w ritten. v\e have examined many
additional specimens of the White-headed Flight-
less Steamer Uuck and have fouiul no evidence for
three molls and plumages per cycle in 7'.
/(7«v)((7'/;(//((.v; nevertheless, a supplemental plum-
age may remain undetected. Although the hypoth-
esized pattern of two molts and plumages per
cycle for this species best explains the limited data
at our disposal, study of specimens representing
all sex and age classes throughout the year will be
needed before a full understanding of the plum-
ages and molts in this species will be possible.
Some of the puzzling data that need explanation
include: (1) May and September-October speci-
mens undergoing body molt in certain tracts other
than head and neck; (2) female specimens un-
dergoing moll in sides, flanks and other body tracts
(Other than head and neck) in September-October
but not males; and (3) definitive alternate plumage
of the head and neck of males apparently not
attained until the third or later prebasic molt in
contrast to coastal Flying Steamer-Ducks wherein
the delinitive alternate plumage apparently is at-
tained by the second prealternate and molt.

Since molts and plumages of steamer-ilucks
appear to be tightly linked to their reproductive
cycles, some of the apparent variability in sea-
sonal occurrence of birds in molt and various
plumage states may be attributable to individual
sariation in breeding activities. Although it is
evident that the majority of White-headed Flight-
less Steamer-Ducks nest during the austral spring
and summer, there may be substantial variation in
extreme dates.

Based on available data, we hypothesize the
following sequence of molts and delinitive plum-
ages for male White-headed Flightless Steamer-
Ducks (Fig. 9); ( 1 ) a prebasic molt which results in
gray cap. red-brown cheek, and white postocular
streak on the head and neck and which also re-
places remiges. rectrices. and the entire feather
coat of the rest of the body; (2) a prealternate molt
which results in an alternate plumage of the head
ami neck vi hich is predominantly white and which
is acqLiiied during the fourth and subsequent
prealternate molts. .As far as wc can determine,
except for feathers of the head and neck w hich are
replaced two times a cycle, the body feathers of

60

UNIV. KANSAS VIUS. NAT. HIST. MONOGRAPH NO. S

adult Whiic-hcadcil I'lighlless Sleamcr-Ducks arc
replaced bul once a cycle by means of a prebasic
molt which usuall\ occurs during a relatively hriel
time in the austral summer.

The same sequence of molts and plumages is
also true for adult females in which the basic
plumage of the head and neck is unicolor dark
brown with a small, white postocular streak. The
delinitive alternate plumage of females comprises
a dark gray crown, reddish-brown cheeks, and a
long. uninterru|ited relatively broad, white
postocular streak.

in contrast to T. hniclixpwius and /.
Ihiuiclioniciis. in \\ hich the definitive basic plum-
ages are dark and unicolor and essential I \ indistin-
guishable Ironi those of females, the delinitise
basic plumage of male /. Iciivoccpludus differs
from that of females and has gray cap. dark cheek,
and v\ hite postocular streak. Except for bill color,
basic plumages of the head of male and female /.
hriiilnprcnis dnd l\ pdhiiiii iniciis show little sexual
dichromalism and resemble the Juvenal plumage.
The only way we can account for gray-capped,
darkish-cheeked males molting into another gray-
capped, darkish-cheeked plumage is by hypoth-
esizing that the pretletinitive alternate plumage of
the head and neck is similar or identical to the
basic plumage.

We can tind no evidence that the sides. Hanks,
and possibly other tracts (apart from the head and
neck) molt more than once per cycle. Neverthe-
less, we have examineil specimens of both sexes
molting or in fresh sitles and flanks in May. and of
females molting or with fresh sides and Hanks in
September and October. We could detect no differ-
ences in the latter case between fresh sides and
Hanks of September-October birds and those of
birds collected in I-'ebruary.

Predelinitive. i.e.. first basic and first alternate
plumages of the White-heatletl I-'lighlless Steamer-
Duck are either imknow n or poorly uniierstood.

Dii iNriivi-: Pl.t MAGrs ot M.\ri-s

Basic Plumage

llciid iiihl ncik. — I-orehead. crown, and nape
dark siray: cheeks and lores medium reddish-brow n;

broail white postocular streak; sides of throat and
chin medium gray: extensive patch on throat me-
ilium cinnamon: white collar at base of neck. For
birils that nest in the late spring or early summer it
appears that this plumage of the head and neck is
attained during the prebasic molt which follows
nesting and is worn until early austral spring (Sep-
tember-October). We collected a male in Decem-
ber, one of a pair w ith \ ery small dov\ nies: the bird
was in high, w hite alternate plumage with a very
lew tiark basic feathers growing in on the cheeks
and anterior forehead. The wings of this bird were
old and worn. We believe that Humphrey and
Thompson ( l'^)SI:<S) v\ere incorrect in their judg-
ment "that following the complete prebasic molt
in summer, both sexes. ..then w ithout interruption
imdergo a partial molt in\ oh ing the head and neck
and possibly otherpartsof the body." Examination
of additional specimens anil photographs indi-
cates that the dehniti\e basic plumage of the head
and neck ol males is worn foi' se\ en to nine months
before being replaced during the early spring by
the alternate plumage.

Lower lircasl. helix, under tail coverts. — White.

Upper hack. — Feathers light silvery gray w ith
narrow tlusk\ -brown margins; anteriorl\. the sil-
\ ery-gray becomes reduced in extent anil the feath-
ers are medium gray w ith narrow, darker margins.

Seopiilurs. — Light siKery gra\ with narrow,
dusky brown margins.

Lower hack. rump, and upper tail coverr.K. —
Medium gray.

Upper hreasi and .v/(/rv. — Six adidt males col-
lected in February have fresh. iuiv\cirn upper sides
and u|iper breasts with \arying amounts of molt,
flpper bieast feathers have reddish-cinnamon bases
w ith narrow blackish-brown lips with sil\ ery-gray
subterminal band. The siherx -gra\ becomes more
extensive in the more lateral feathers and upjier
siiles. l-'eathers of the upper breast and sides are
\ er\ w orn in a December ailult male anil less so in
two September specimens. In the two September
s|iecimens the upper breast feathers are medium
rcildish-cmn;uiion with narrow blackish-brow n
subterminal bands and \er_\ nariow. fra_\ed. failed
smoke-gra\ tips. l.aterall\. the cinnamon is re-
placed by light to mcilium-gra\. In the December
s|iecinien. reddish-cinnamon occius in a wider

STEAMER-Dl'C-KSiANATIDAE: IMHYFRES) 61

expanse o\ leathers lateralis and inan\ ol the Iniiiteil to the head and neek and oeems. as lar as

leathers ha\easniall subterminal white spot. Wear weean determine, in .September and Oetoher. 1 his

on tiie ujiper breast has eliminated most or all ol plumage is worn until the eomplete prehasie molt

the subterminal dark band so that many ol the whieh usually occurs in the austral summer lol-

feathers are faded cinnamon with tra\ed paler tijis. lowiny the nesting season.

Silk's ami fiaiiks. — Light silvery-gray with

dusky-brown tips. In some specimens the leathers DEFiMTivn Pri macu^s oi- Fi^mai.e.s
are somewhat darker sil\ery-gra\ and max have

les.s silvery sheen. Posteriorly, the Hank leathers Bisi ■ Plumi>'^
have broader dusky-brown tips than those in the

sides. Three September specimens and one col- Haul iiiul iu\k. — Unicolor dark brown, neck

lected in December have worn and laded sides and slightly paler; small, while postocular streak,

flanks in which tiie tips have become lighter and Lower hreasr.hclly.iiihlcrhiil coverts. — White,

browner. In the December specimen wear has Upper hack. — As in delinitive males except

made the dark leather tips narrower and with pale that feather margins are wider aiul are sepia to

frayed edges. It appears that the sides and Hanks o\ brow nish-oli\e in color.

definitive males are replaced only once a cycle Sicipiilars- — As in dettnitive male except that
during the prebasic molt, usually in the austral the featiier margins are wider and sepia to brown-
summer. Thus, males are wearing worn sides and ish-olive in color.

flanks when the heatls and necks are in fresh Lower haek. ruiup. and upper tail coverts. —

alternate plumage. Dark gray, feathers of the lower back and rump

Remi^^es and rectrices. — Black or blackish- faintly silvery with narrow, indistinct darkeredges.

brown with varying amounts o\' silvery-gray on In worn birds (several February specimens), the

their dorsal surfaces. Primaries and greater upper leather edges are frayed and broadly tipped with

primarv coverts dark dusky-brown with blackish- huffy brown and worn smoke gray tips,

brown shafts; rest of upper wing medium fuscous. LI pper breast and sides. — As in definitive male.

Secondaries white, the inner vane of the innermost A specimen collected in September had fresh up-

ones medium blackish-brown; teilials medium dusky per breast and sides with a very few new feathers

brown. AxiUaries and central part of wing lining still growing. It is puzzling that some females were

white; balanceofunderwingeovertsmediumdusky- molting or were in fresh upper breast, sides, and

brown, the greater under primarv coverts paler, flanks in September.

Rectrices dark blackish-brown, with black shaft and Sides and thinks. — Light silvery gray (as in

faint mesial wash of white silvery-gray. definitive malesi with feather margins broadly

chestnut. Sides and flanks of delinitive females m
fresh plumage have much richer reddish and w iiler
feather margins than males; this gives the sides

As lar as we can determine, only the leathering and flanks of definitive females a more heavily

of the liead and neck is replaced during the scalloped appearance than m males. Sides and

prealternate molt. flanks of a definitive bird collected in September

Head and neck. — Predominantly white. Some were identical in appearance to new feathers m

individuals have a medium gray cap of varying February specimens. We are uncerlani about num-

extent (size and extent possibly varies with age); ber and timing of molts of sides and thinks in

in others, the forehead and crown is white. There definitive females. We have found extensive molt

are varying amounts of pale smoky-gray in the in delimlive lemales m both September anil Febru-

lores and anterior cheeks. The chin is pale smoke- ary but the leathers are identical. We have found

gray grading posteriorly into a relatively narrow noevidenceof moliduring Seplemberof sides and

patch of light brownish-red or light cinnamon on Hanks in definitive males,

the throat. The prealternate molt apparently is A leucistic female 7. /(7((V*((7)/«////.s ( SW .vS,^ I

Alternate Plumasze

62

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

= KIJ 77936) vvascDllcck-d at PuciU) Mclo. C'luibiit
on 28 September 1979; the bird was evidently an
adult (ovary 20 x 20 nun. body mass 2S?() g). and
was conspicuously liizhicr than nearby conspe-
citics, even al a distance. The leiicisiicism affected
all pterylae.

Alternate i'kmiage

llcoil (ind iivck. — Crown gray, cheeks redilish
brown becoming light grayish-brown posteriorly.
long, unmterrupted, white postocular streak.

Predefinitivi; Pium.age.s or M,\i.i:s

Basic Plumage

Head and lu'ck. — A specmien (KU 79243) col-
lected in February from a family group comprising
two adults and four or Hve young had wings onl\
partly grown with the primaries about 1 0 cm out of
their sheaths. This specimen has slight molt on the
heatl and neck which we interpret to be (he end o\
the lirst jirebasic molt.

A male (KU 79233) collected on 1 1 February
had a vestigial bursa of Fabricius and had just
completed most of v\ hat we considei to have been
its third prebasic molt. However, this prebasic
molt of the heail antl neck was still tuidervvay and
ihe alternate iilinnage being replaced on the head
hatl ilarkish cap. cheek and w hite postocular streak,
suggesting that the preiietinitive aliernale plum-
age of the head anti neck (second alternate) is
similar in aspect to the detinitive basic plumage.
Another male (KU 79236) with vestigial bursa
collected S February had grow ing remiges. prima-
ries about 10 cm long and secondaries about 1.3
cm, and was in heavy molt in all regions of Ihe
body. The retained, worn, presumably secoiul al-
ternate feathers of the head and neck were compa-
rable in aspect to the delinitive basic plumage. We
hypothesize that the dehmtive alternate plumage
ol the head and neck ol niales does not occur until
three years ol' age. i.e.. before the thiril or subse-
t|iieni preallernate molts.

Sides and Jianks. — New lirst basic feathers
growing in on a September male with many re-
tained juvenal leathers are like the dclmiliv e basic
feathers of the sides and Hanks.

Pki:di:iimii\ L PlL-\i.jiGi;s oi- Fi;mali£s

Basic Plumage

Upper hack. — Compared to the definitive fe-
male, feathers of the first basic female upper back
have less intense silvery gray and narrower mar-
gins that are dark gray.

Scapidais. — Compared to definitive females,
the scapulars of the first basic female are less
intense silvery gray and have narrower margins
that are brownish-olive. The first basic plumage is
less "contrasty" silver versus rich brown than is
the definitive basic plumage of females.

Lower hack. rump, and upper rail coverl.s. — A
female collected in September had lower back and
rump as in definitive female.

Upper hreast and sides. — Upper breast and
sides of iwo females collected in February with
large bursae (in first basic plumage) were like
definitive basic upper breast and sides.

Sides and flanks. — A presumably subadull fe-
male collected in September (ovary 2.3 X 13 mm)
had unworn sides and flanks light silvery gray
(more extensive on each feather than in definitive
birds) and with narrower chestnut margins which
were less richly chestnut than in definitive birds. A
female laken in February with vestigial bursa had
fresh sides anil Hanks mixed with more light sil-
very gray on each feather and narrower brow ner
margins than in the ilefinitive specimens.

Jiivi;n.ai. .vnd Downi Pi i m.ac.es
(BoiH Si:.\ts)

Juvenal Plumage

We collected Ihree s|iecimeiis (two males, one
female) m complete juvenal plumage (KL' 7924.
KU 79243. and KU 79244). All three specimens
were collecled from family groups in February
1981 at Puerto Melo. Remiges on each of the
specimens were only partly grown, hav ing devel-
opeil 3-10 cm i)ui of their sheaths. Based on these
specimens, ihere is lu) sexual tlimorphism in ihe
juv enal plumage and birds of both sexes are iden-
tical at this stage of deveU)pmeiite\ce|M iluil males
are somewh.ii lari;er ihan tem.iles.

STEAMER-DUCKS (ANATIDAE; lACHYERES)

63

/Icciil diiil ih'ck. — LInicoliir tlark bidvsn. neck
paler; iiKlisiinct pale bLiHy poslociilar slreak.

Lower breast, helly. iiiuleriail coveris. — White.

Upper hark. — Feathers medium gray but
siigiillv darker than tiiose on the upper breast and
sides. Kach leather has a dark, blaekish-gray ter-
minal band 3—4 mm « ide.

Scapulars. — Outer webs medium gray: inner
webs medium brownish-gray. Each leather has a
blackish-brow n margin: some leathers hav e a taint
tan tip which may be a vestige ol the lormerly
attached down.

Lower hack, niiiip. and upper tail coverts. —
Mediimi gray.

Upper hreast and sides. — Feathers dull me-
dium gray or brownish-gray for most of their
lengths, with a blackish-brown subterminal band
about 2-3 mm wide and a terminal band of light
brown. A few feathers at the junction of the upper
breast with the v\hite lower breast have a trace of
mediinn cinnamon just proximal to the dark termi-
nal band.

Sides and flanks. — Medium brownish-gray, each
of the feathers with a taint v\ ash of pale pearly gray

aiul a medunii-hrow n margin, becoming slightly
lighter at the lip.

Downy Plumage

The following description is based on hvechiss-
I specimens from Chubut. Argentina, collected
during 12-14 December I MSI: MACN 5269S
(male), KU 79624. 79625 (unsexed anatomical
specimens), KU 79501 (female), and KU 79502
(male).

Head and neck. — Upper and lower eyelids
whitish to pale pearl gray. Cheeks light to medium
grayish brown becoming paler ventrally and pos-
teriorly in some individuals. There is a dark gray-
ish-brown streak through the eye along the dorsal
margin of the cheeks and lores. Fores light to
medium grayish-brown. Supraloral patch broad
and continuous with the supraocular patch and
poslocular streak, all being whitish or pearl gray.

L'ppeiparts. — Yoke light grayish-brown: rest
of upper parts dark grayish-fuscous.

UnderpiU-ts. — Upper breast medium grayish-
brown; lower breast and belly white.

DIAGNOSTIC CHARACTERS

Generic Characters

E.XTERNAl. CliAKACrRR.S

Steamer-ducks of all species are readily di.stin-
guishable from other waterfowl by the combina-
tion of large size (2-6-f kg), white wing specula,
predominantly gray body color w ith white under-
parts, heavy bill, dull reddish throat patch, bright
orange feet (in adults), variably developed wing-
knobs, and (in most plumages) light postocular
streaks, and the absence of metallic hues or
contrastingly pale fore-patches on the dorsal sur-
faces of the wings. The three flightless species of
Taeliyeres are the only large (exceeding 1 kg in
body mass) extant anseriforms that are perma-
nently incapable of flight. Within their natural
distributional range, steamer-ducks conceivably
could be confused only with the much smaller
Crested Duck (Lophonetta speciilarnndes} or am
of the three sympatric species ot sheldgeese

(Chloepliai;a): both of these genera are readily
distinguishable from Taeliyeres by their metallic
wing specula, dark bills, variably patterned but
non-gray body plumage, ami (in Clil<iepha;j.a)
while forewings.

Skieletal Ciiaractf;rs

Less obvious are the diagnostic skeletal charac-
ters of Tachxeres. Ave of which are derived and
evidently unique among .^nseriformes (Livezey
1986a). Femora of steamer-ducks possess well
developed intermuscular lines on their caudal sur-
faces, lines which characteristically are produced
into irregular, folded ridges proximally (Fig. lOA).
Carpometacarpi o\'Ta( hxeres are characterized by
deep, ovoid cuneiform lossae (Fig. I OB). The
scapulae of steamer-ducks possess unusually bul-
bous. \enti"all\ protrusive coracoidal facets (Fig.
IOC). The robust. iieaviU armored skulls of

()4

UNIV. KANSAS MUS. NAI . HIS I . MONOGRAl'H NO. 8

TR

Fig. 10. Unique skelclal characters of Tathycrcs (ilrawn from 7'. plencres. KU 79842): A — caudal view of
proximal end of femur (HD = head) showing promineni inlemuiscular ridge (IR); B — caudal view of proximal end
of carpomelacarpus (TR = trochlea) showing deep, oxoid cuneiform fossa (CF): C — proximal end of scapula (BL
= blade) showing bulbous, ventrally protrusive coracoidal articulation iCAl; D — lateral view of preorbital region
of skull {L\ = lacrynial process. OR = orbit) showing prominent, dorsolalerally projecting, knobby supraorbital
process (SP): E — lateral view of cranial (preacetabuhni portion of pelvis (.AC = acelabulumi showing \ariably
deep, irregular depression in iliac fossa (IF-).

STEAMER-DUCKS (ANATIDAE: lACHYERES)

65

siLMiiiLT-diicks MV quite distiiicti\L' (F-ij;. I ). ami
iiiatLiie birds possess supraorbital processes u Inch
are unique anions: Anseriformes in tiie eonibina-
tion of dorsolateral orientation and thick, rugose
structure (F-iy. lOD). Finally, members ol tlie ge-
nus have pelves featuring variably deep, irregular
depressions in the (preacetabular) iliac fossae (Fig.
lOE).

Dktkrminahon of A(;k

Unfortunately for purposes of identirtcation.
the distinctiveness of the genus Tuchycrcs is
matched h\ the difficulty of distinguishing the
four member species. The majority of the qualita-
tive and mensural differences among species reli-
ably apply only to adult (at least fully ossified.
Hedged) specimens, and therefore our review of
species diagne)ses is preceded by a consideration
of techniques tor determuiation of age of speci-
mens.

PiAiMACiE AND Soft Paris

Do\\n\ steamer-ducks are not likely to be con-
fused with adult birds; identifying characters were
di-scussed by Humphrey and Live/ey (I9S5) and
are summarized beyond. Juvenile steamer-ducks
(no longer downy) usually can be separated from
older birds by a combination of several external
characteristics, .luveniles not yet fledged can be
singled out in the field by their small si/e (body
mass often I kg less than accompanying adults).
the presence of incompletely grown (sheatheil)
primary remiges (also occur in adults in prebasic
molt), and the aggregation of birds into groujis
larger than two. Plumages of juveniles of all spe-
cies are darker. se,\ for sex. than the respective
adult plumages, are almost devoid of white (in-
cluding the postocular region), are distinctly more
brown than gray in the general color of the head
and neck, and the reddish throat patch is very faint,
.lusenal rectrices differ from those of subsequent
plumages in having distinctive terminal notches.
JuNcnal plumages were described earlier for '/'
Iciicoccplhihis illumphrey and Thompson U'SI)
aiul / piitiH htiiiu us (Humphre\ aiul Li\e/e\
1982a).

Hills ol |u\enile lacliycirs of both sexes virtu-
all\ lack orange coloration, and typically are dark
bluish or greenish black. With increasing age, bills
ot males (both sexes of T. picncrcs). become pro-
gressiveh more orange until the dark tones are
limited to small areas beneath the nostrils, al-
though this trend is complicated by a seasonal
darkening of bills of males during prebasic molt
(Humphrey and Live/ey 1982a). Foot color shows
a parallel developmental trend, being dull tan with
comparatively prominent "knuckle" marks in many
older predefinitive specimens (Humphrey and
Livezey 1982a). As with the coloration of the bill.
the feet of dehnitive males become less orange
during wing molt.

Wing spurs are generally vsell de\'eloped in adult
Tadixcrcs but there is substantial individual, age-
related, and sexual variation in this structure. Juve-
nile birds and some yearlings show little or no
enlargement of the spurs, and the overlying skin is
relatively thin, fully feathered, and dull grayish flesh
in color. Spurs of older birds typically become much
enlarged, covered with bare orange skin, and often
arc equipped with a thick comihed knob: the degree
of this development varies among individuals, evi-
dently because of differences between birds in the
frequency of wing-assisted combat. The structure is
useless for identification of species.

Skeletal Development

Fledgling Tachycics often retain signs of im-
maturity in certain skeletal structures, the juvenil-
ity of which is indicated by incomplete ossirtca-
tion and/or thickness. Incompletely ossihed ele-
ments remain comparatively pliable when fresh
and. aftercleaning and drying, often become some-
what chalky or easily warped. Several skeletal
structures are prone to stich late development in
Tiultycrcs. notably the caudal margins (margo
caudalis) and carina of the sternum, the antorbital
processes of the skull, and the distal-most limb
elements, especially the phalanges. Also, the cra-
nium becomes progressively thicker antl more
rugose during the hrst few years of lite; those of
ju\eniles appear comparatively smooth, and su-
ture lines between cranial elements remain dis-
tinct in very young birds.

66

I'NIV. KANSAS MlIS. NA!\ HIST. MONOdKAI'H NO. 8

BlR.S.A .Wl) G0N,\DS

As in waterfowl generally (Hochbaum IM42,
Shortt 1943. Elder 1946. Davis 1947. Hanson
1962). the bursa of Fabrieius (eloacal bursal in
Tachxcrcs shrinks with age. in juvenile steanier-
dueks the bursa is large and glandular, shrinks to
modest si/e in yearling birds, and beeonies vesti-
gial or disappears entirely in older speeimens
(Humphrey and Livezey 1982a). Despite signili-
cant inlerspeeilie differences in body mass, an
inverse association between sizes of bursae and
gonads is demonstrated in both sexes, even if
species are pooled (Figs. II. 12). There is. how-
ever, considerable variation in this overall rela-

tionship due in large pari to seasonal \arialion in
si/e ot gonads. The precise age at sexual maturity
in Tcultycics is not known and ma\ \ ar\ among the
species: it appears that most paired birds on terri-
tories are 'adults.' i.e.. ha\e no bursa or bursa of
vestigial si/e. and are estimaletl to ha\ e attained a
minimum age of two years ( Humphrey and Li\ ezey
1982a).

Although specimens of .Analidae are most fre-
quently classilied losex on the basisof gonads, the
svrinx piovides another means for Tadorninae and
Anatinae. uherein the syrinx is enlarged into an
asymmetrical bulla in males. This criterion is par-
ticularly useful lor skeletal specimens anil freshly
collected downv voune (Beer 1962).

6,8

6 4

6,0 -4

5,6

<

5.2

O 4 8

44

4,0

36

32

2 8

2 4

■y/-

T r 1 r

^

O •

MALES

D

• •

D
D

-//-"

9 palachonicus

n leucocephalus

A brachypterus

O pteneres

_l I L.

O

D

D

D

_i_

_i_

_i_

none

'old"

30

36

4 2 4 8 5 4
SIZE OF BURSA

60

66 72

■^"young"

Fig. 1 1. Logarilhniicplol ofsi/es (products of maximal Iciiglhsandw idths) of testes and cloacal bursae lor males
of four species of huhyvics. Means, ranges, and sample si/es of testicular areas are depieled for speeimens lacking
bursae.

STEAMER-DUCKS (ANATIDAE: TACHYERES)

67

6 8

64

Q 60
<

O

<^ 5 6

o

5.2

4.8

4 0

v/-

o

FEMALES

'^

o

n
A •

• patachonicus

D leacocephalus

15 A br achypterus

O pteneres

-//-

A

D
A

D

O

_!_

none 3 0
" OLD" -•

36

42 48 54

— SIZE OF BURSA —

66

■A.

Fij;. 12. Logiinthmic plot dlsi/cs (producls of nia\iiii;il lenglhs and widths) ol'ovarles and cloacal
females ot four species of l\n hxcics. Means, ranges, and sample sizes of ovarian areas are liepicted for
lacking bursae.

72

'young"

bursae for
specimens

QiALiTATivE Characters of Spkcies

E\ti;rn\l Difkerences

Except for \ariali(ins in the amount of reddish-
brown on scapulars, sides, and flanks, all steamer-
ducks have essentially the same aspect from the
neck down. i.e.. body battleship gray with white
lower breast and belly. Coloration of the head and
neck is extremely variable both within and among
species. In its hrst two years of life, a steamer-
duck, depending on the species, may wear five ('/'.
piciicre.s. T. Icucuccplnilus) or seven ('/'.
hrachypicriis. T paiinluniicus) plumages (Fig, ^)),
Moreover, because steamer-ducks may nest any
month of the year (most nest in the austral spring
and summer. i,e,. October-January) there may be
considerable variation in the chronology of molts.
The situation is simplified (or complicated) by the
fact that most iif the plumages are so similar thai
they cannot be distinguished from superficial ex-
amination and many of them ( first-year plumages)
are still unknown.

T puhicluinn us antl 7 hnulnpicrus ha\ e three
molts and plumages peryear(Fig. 4). In dcfiniti\c

males, the supplemental ("'breeding") plumage of
the head and neck is predominantly white and
from a distance the birds look completely white-
headed in that plumage. The supplemental plum-
age in most individuals is w orn for a month or two.
usually during October-January. The supplemen-
tal plumage is followed by a basic plumage in
which the head is unicolor dark brown. This is
worn for a few weeks at the most and is followed
by an alternate plumage in which the males have a
dark gray crown, darkish cheeks, and a broad,
white postocular streak.

7'. Icucdccphalns and T. ptenercs have, as far as
is know n, two molts and plumages per cycle (Fig.
M), Males in definitive alternate plumage appear
white-headed but. in the hantl, 7 Icukh cplialus
ma\ have varying amounts of light to medium
gra\ on the forehead and T. picncrc\ may have the
w hole head and neck pale gray to white. Female T.
Icin <H rpluilus in definitive alternate plumage has
a hroad. white postocular sticak. d.irk cap. and
somewhat lighter cheeks. Female 7. ptcncves in
definitive alternate plumage has medium gray head
and neck, cap somewhat darker, and differs from
alternate females of the three other species in

68

L'NIV. KANSAS MUS. NAT. HIST. MONOCiRAPH NO. S

having an orange bill and lacking a consiiicimus
white postocular streak. Comparative summaries
<)t"theiletinitive]ilumagesot all species olsteamer-
ducks are set torih in Tables I and 2.

Of the tour species oiTachyercs. adults ot OuIn
one can be identitied conlidently using characters
ol plumage pattern anti soft parts. This unit|ue
species is T. ptciicirs. the atiults of which ddler
from those of their congeners in lacking signiti-
cant sexual dichromatism. both sexes having en-
tirely orange bills (except the black nails) anil
predominantly gray heads and necks; the species
also is unique in virtual absence of chestnut hues
in the scapulars, sides, and Hanks (Figs. 4. '-)).
.Adult female T. Iciicoccpluilus in alternate plimi-
age differs, less obviously, from females of other
Tiulixcrcs in having comparatively broad
postocular streaks (Fig. 9). Murphy ( 1936) made
reference to a "golden collar" of feathers at the
base of the necks of some T. hi\uh\plcitis. a
character offered as an aid in separating /.
hriichxpicrus from the smaller, sympatric 7.
pdfiK hoiiiciis. We have been unable to distinguish
this character in T. hnultyplenis, either on study
skins or in the Held. In other respects, adults of the
three sexually dichromatic species — T.
pataclioniciis . T Icitcoccplnihis . and /.
hracliyptcnis — are not distinguishable using t|uah-
tative features of plumages and so{\ parts.

Murphy (1936:955). evidently stimulated by
the descriptions and counts of remiges in 7'. picucirs
given by Forster ( 1844) and Bennett 1 1924). stud-
ied differences between T. iUl'iutvs and 7,
p(i!(i( lionii ii.s in the |iatterns and amount ol w lute
on the seconilary remiges: "In both species the
outermost one or two secondaries have a slight and
variable dark subterminal spotting. If we disregard
this, and count Ihc secondaries inwaril. we lind
that in pulaclioniciis the lirst ten, eleven, or twelve
quills are white, the lirsi dark marks appearing on
the inner web of the eleventh, twelllh.oi' thirteenth
feather. In most instances the next succeeding
feather is entirely dark. In picncrcs. only six.
seven, or eight secondaries from the outermost are
w hite. the gray markings usually beginning on the
inner web of the eighth or ninth, succeeding quills
after the first spotted one being more or less liark
on both webs or entireh dark."

We tested this distinction bs sketching on stan-
dan.1 forms the color jiatterns ot the secondary
remiges of all birds collected. Selected diagrams
of each species and sex are depicted in Figs. 13-
17. Counts of "white" feathers were difticult to
ntake because of the spectrum of degree of spot-
ting observed. Murphy ( 1936) chose to disregard
the "slight and variable dark sublernnnal spotting"
he observed in the "outermost e>ne or two second-
aries." We founil it difticult to determine the anunnit
of spoiling that should be considered "slight." and
the extent of spotting that should be classitied as
"subterminal." Further problems resulteil from the
variable basal shailing noted in man\ birds, and
the contmuum of shades from white through gray
to black that was observed.

Whaie\er rules one adopts, the shading pat-
terns in secondary remiges of T. picncrcs and T.
puiavhoniciis appear to be quite similar, and any
difference in "modal" condition would be unreli-
able for species diagnosis. We found that T.
puiaclioniiiis almost never has 12 largely white
secondaries: this was true of all the other species
as well. Specimens of all four species typically had
10 to II "largely white" secondaries, although
there was a tendency for T. picncrcs to ha\ e more
heavily marked secondaries, prompting us to count
only nine "white" secondaries in some specimens.
We ne\ er found a specimen with only six or se\ en
of what we would judge to be white secondaries.
Wing patterns of T. hrachyptcrus and T.
Iciifoi cplhilus were indistinguishable from those
of 7, pin(i( lidniciis.

Sexual dichromatism ni shadmg patterns may
further complicate these patterns. In the 7".
hnuliyplcnis we collected, we found a dark termi-
nal spot on the t)ulermost (first) secondary in nine
often females, but this mark was absent m all 1 1
males. Lastly, we doubt that this technique could
be aliempted effectively with dried skin speci-
mens, because of reduced access to the secondary
remiges.

Fresh tlowns \oung are identifiable to species
using characters of the head patterns of the natal
plumage. These differences were assessed by
1 himphrey and Livezey (1985 ), work based in turn
on ihe earlier diagnoses presented by Fowet 1934)
and Murph\ ( 1''36). Briefls. dowiix xoung of 7. /

STEAMER-DUCKS (ANATIDAE: lACHYERES)

69

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70

LINIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

Tabic 2. Suniiiuny of generalized aspects of heads and necks of iinhyeres in definitive plumages, by se,\ and
species.

Sex

Plumage of head and neck

Species

Basic

Alternate

Supplemental

Male 7", ptiuii Iioiik iis

T. hiachyiilcnis

T. U-iicciephiiliis

'/', ptcncics
Female /. paun liitnii lis

7. hi lu lixplci us

Unicolor dark brown

Unicolor dark brown

Gray cap. brown cheek. Largely while
while pitsUHuUir stivak

Gray cap. brown check. Largely white
white postocular streak

L^ark cap. brown check Largely white
w hitc postocular streak

Dark cap. gray check
Unicolor dark brown

Unicolor dark brown

Pale gray to w hile —

Dark cap. brown cheek. Cap gray, cheeks

white postocular streak brown, sluirl white

interrupted ni middle postocular streak

Dark cap. brown cheek,
w hile postocular streak
loni;. narrow, unbroken

Same as altemale

7". IciuiHcplialiis Unicolor dark brown Dark cap, brown cheek,

postocular streak short white postocular streak
loim. w ide. imbrokcn

7' piciicrcs

Dark gray cap. meduini Dark gray cap. ?iiediuni
gray cheek gray cheek, short pale

gray postocular streak

''Plumage not documented.

Iciicoccplhilus ililTcr from those of other Tachycivs m
having w liilish ( not ilark ) ii|ipcrey olitls and the crow ii
being darker than the cheeks. IJowny 7 ptciwivs are
distingtiishable from the ilowiiies of other Idcliycirs hy
their cli\ itied (Iwo-paileil) postocular streaks and li\
thcirvcry small (orahscnl isupraloral and supraocular
patches. Downy specimens of 7. pahnluiiiuiis tliffci
from those of T. Iciicriccplhiliis in color of eyelKl.
relative tiarkness of crown, and b\ ha\ing nariow
supraloral and supraocular patches which are separate
t'roin tlie postocular streak: from downies of 7.

pU'iu'ivs in having a continuous (not two-parted)
postocular streak: and from those of 7'. hnicbyptciiis
ill has iiig the posioctilar streak separated from the
supraloral and supraocular patches. Downies of T.
hiiu Inpicnis differ from those of 7'. Iciicoccphahis
m eyelid color and the narrowness of the supraloral
and supraocular patches: fnmi downies of 7/ vr/u'rcv
in ha\ ing a continuous (not two-parted) postocular
streak; and from the young of T. piihn honlriis in
having the supraloral and supraocular patches con-
tinuotis w ith the postocular streak.

STEAMER-DUCKS (ANATIDAE: TACHYHRES)

71

B

D

X

o
q;

Q.

Fitz. L^. Diagiiinis ol shadiiii; patterns of secondary rcmiycs (wing specula) ol selected /, pahuluiim us Ironi
maritinie coastal sites ol Argentina: A — male. Ushuaia (KU 7420.^); B— male, Puerto Deseado (KU 79215): C —
male. Puerto DeseadotKU 79214): D— female. Ushuaia (KU 79190); E— female, Ushuaia (KU 79192); F— female,
Puerto Deseado (KU 74209); Ci— female. Puerto Deseado (KU 79212).

72

UNIV. KANSAS MILS. NAT. HIST. MONOGRAPH NO. S

B

D

X

o

Ql

^vl/w

Fig. 14. Diagrams of shading pattcms nl sccorularv iciiiigcs (wing specula) of selected /". patculumicus from
Andean lakes (Argentina and Chile) and the coast of central Chile (Ens. Huito. Region X); A — male. Lago Fontana
(KU 79471 ): B— male. Lago Roca (KU 79460); C— male. Lago Rupanco (KU 79836): D— male. Ens. Huito (KU
798.S4): E— female. Perilo Moreno (KU 7946.^); F— female, Lago Rupanco (KL 798.^5); G— female. Lago
Fulalaufquen (KU 79476).

STEAMER-DUCKS (ANATIDAE: TACHYERES)

73

A

B

C

-I \^

CL

D

l^

v_y

\^

^^v_y

Fig. 15. Diagi'iinis of shading patlerns ol secondary rcniigcs iwnig specula) ot selected 7 hiaihxpiciiis Irom
Lively Island, east Falkland Islands: A— male (KLI S(1.S15); B— male (KLI SIIS.^O); C— female (KU SO.'S:'-)); D—
female (Kf X().'S24).

SKRLET.^L Differences

Osteological comparisons played a crucial role
in the conclusive diagnosis of flighted and llightlcss
steamer-ducks by Lowe ( 1934); the relative lengths
of selected elements, notably the illustrations of
humeriandstemaof /'./'(/;</< 7/('/;/r(/.v and 7. /)/('//(';c,s
(his hniclnptcnis). added a new dimension to the
problematic mterspecittc differences in size and
plumage. However, like the relative thickness of
limb elements and sternal conformation of 7"
Iciii (Hcjilhilw. illiisirated by Humphrey ami
Thompson I IM.SI ). such skeletal proportions aie
treated more eftectively as quantiiativc. statisti-
cally comparable characters (see below).

As part ol a phylogenetic analysis of the genus
Tiniiycrc.s. Live/ey ( mSftc) listed nine qualilaliv e
characters which varied within the genus. Despite
moderate intraspecitic \ ariation in several of these
features, these characters can provide additional
aids lo identilication of skeletal remains of

Iculncres (e.g.. weathered carcasses), clues that
are independent of the more traditional compari-
sons of plumages and measurements. ,'\natomical
terminology used in the following descriptions
follows Baumel el ul. ( 1 974).

Two characters of the skull — one involving the
occipital condyle and the other the pnncwMis
niaiulihuluc medial is of the mandible — vary among
species of Tachycrcs. In T. picncrcs. the occipital
condyle is produced ventrad to the plane of ihe
hasioccipital plate, whereas in other Tmhycrcs the
condyle is more dorsal in position (Fig. IS). The
piiH vssiis fiuiiulilnilcic mcdialis has three qualita-
tively distinguishable conditions in the genus ( Fig.
19): in T patiu honiciis the process is almost with-
out medial inflection; in the sister-species T.
hi (ii li\picru\ and 7". Iciicm epiidlii.s there is moder-
ate inllection; and in T. picncrcs the medial inllec-
tion is pronounced (state for T. picncrcs incor-
rectly given in Table I of Live/ey 19S6c).

74

UNIV. KANSAS MIS. NA'l . HIST. MONOGRAPH NO. S

B

D

ca

Fig. Ki. Dl;igr;ims ol sluuliny piiucms of secomkuN icniigcs (\\ mg spcciilai nl m.'1c(.Ic\I /" plciieres: A — male.
UshuaiiKKU 79178); B— male. Usluuiia(Kli 79179); C— female. UsluuiialKL' 79IS1 ); D— lemale. L'sliuaia (KU
79194): E— male. Ens. Codihuc, Chile (KU 79842); F— female. Ens. Codihue (KU 7984.^).

The carpomelacarpiis li;is foLiit.|Li;ililati\e thar- tnnlilcu carpalis vcutvalis (internal rim of L'arp;il

acters useful for distingLiishinj! speLies-sLibt:n)iips trochlea) extends caudally be\ond the os

of Tachycrcs. The attachment site or 'sear' of M . iiwhicarpale minus (metacarpal III) in T. pwiicrcs.

extensor nictacarpi iiliuiris is proxinud to the whereas in other species of Vi/r/nt'/v.v the former

synosiitin incuicarpi proxinuilis (proximal meta- approximates the latter in caudal extension (Fig.

carpal fornix) in Hightless species, but is coinci- 20). A small (unnameti) tuberosits on the

dent vsiih it in / puiiiclioiiii us (Fit;. 20). 'I'he proximocaiidal •^urtdcc o( os nu'liudipiiU' minus

STEAMER-DL'CKS (ANATIDAE: lACHYERES)

75

B

C

X

o

Q_

D

Fig. 17. Diagrams of shading patterns of sccondarv rcniigcs ( « nig specula) of selected /, Icuitn cphnlus Ironi
Puerto Melo: A— mule (KU 74246); B— male ^KV 742.^5); C— lemale iKV 744.^7); D— female iKV 74240).

(tnctMcarpal ill) isseparable ttitd three si/e classes:
iiKlisiinctl\ developed in most T paliicluinicus:
moderately developed in T. hrachypicnis and T.
ptcncrcs: and comparatively conspicuous in T
IciicdCi'phalus (Fig. 20). Finally, the distal termi-
nus of the sulcus U'lulincus assumes two distinct
conformations: an open, indistinctly ridged chan-
nel in T. paiachonii us and T. picncics: and a
proximo-disially abbreviated passage surrounded
by prominent, typically pointed, and sometimes
joined Mips" in 7". hrachxpteius and 7',
Icucdccpluilus (Fig. 21 ).

Three other elements of the pectoral limb pro-
vide useful L|ualitati\e characters in Ttniiycirs —
the radius, coracoid. and scapula. The radius of T.
IcuciHcpluilus is distinguishable from those of its
congeners by the proximally appressed scapholunar
facet (Fig. 22 l. The coracoids of flightless species
ofTacliycrcs differ from that of T. puiiuiiouicus by
the two-layered aspect of the fcnics aiticularis
slcnuilis vcntrulis (\enlral sternal facet). The de-

gree of torsion of the carpus scdpiiliic (scapular
blade) also distinguishes /'. puuicltmucus from
flightless steamer-ducks, being (variably) greater
in the latter.

Gi\ en the flightless condiiioii of three species of
Tacliycrcs. it might be expected that there would be
interspecific differences in the sternum, especially
in the development of the carina (keel). Li\'e/ey and
Humphrey (l'-)86) documented signihcant statisti-
cal differences among species in rclaiivc (but not
absolute) depth of the sternal carina, but \ ariation in
this structure and large interspecific differences in
sternal size render non-mensural appraisal of ster-
nal differences problematic.

Quantitative Character.s of Sppx ies

External Me.^slrements

.All external measurements, inchiding the stan-
daiil tlimensions gi\en in the s|iecies accounts.

76

UNIV. KANSAS MLIS. NAT. HIS I. MONOGRAI'H NO. 8

Fig. IS. Occipital coiulylcs (slipplcd) o\ Tat livcrcs.
showing the comparatively vcnlral poMiion ollhal in /
in cite res: A — T. hraclixpuiits (KV X().S27i; B — /
pleiwn's (K\J 79842).

dilTcrcd siynilicantlx ainoni: s|icc:cs (/^< 0.001 i.
Most incasuivmcnls also iiit'torci.1 hclwccn ihc
sexes, the only c\ce|ilions being ciilmen lenglh
and lamellar count ( Tahlc }). \\\ but latiiellar
coutil. wing length, and tail length ranketi species
in accordance with total boiK mass: / piciwrcs
largest, t'olloued b\ /, hi m li\ pui us. I
IciK IK cplniliis. ami / p<iun liiniii us. Although

there is o\erlap among species in most measure-
ments, study ot'suitesof measurements. especially
ol combinations of size-correlated and si/,e-op-
[losed measurements, provided effective species
diagnoses in most cases (Table 3).

Lengths of the primary reiTiiges{ (light feathers)
provide similar information for species identilica-
lion. We collected and measured two remiges —
the ninth (longest) primary and the first (outer-
most) secondary from each specimen collected
during U)iS0-S4 that was iK)t in wing molt. In all
tlimensions recorded — total length, length of vane,
calamus length (from umbilicus), and calamus
width (at umbilicus) — T. paiin Imntcus exceeded
its more massive, flightless congeners (Table 4:
Livezey and Humphrev I9S6). Of the flightless
species. T. Icucincpluihis and T. hnn hypicru.s had
longer remiges than the larger T. ptcucrcs (Table
4); this ranking of total lengths largely reflects the
longer vanes of '/. IcuciHcpliiiliis ami /'.
hnniiypwni.s. in that the calami of 1. prciicir.s
exceed in length those ofthe two smaller, flightless
species (Table 4): \\idths of calami (not tabulated)
followed lengths of calami in interspecific and
mtersexual rankings. These interspecific differ-
ences in lengths and proportions of primarv and
secondary remiges can be useful aids to identifica-
tion of TdilnciT.s. especially for separation of /'.
pdliii liniiicus from its llightless congeners (Fig.
2.^). For purposes of identification, however, care
tnust be taken to exclude from comparisons speci-
mens with significantly worn remiges. a frequent
condition in all species of Tachycrcs. especially
the flightless species. .Also, juvenile birds (i.e.,
specimens with juvenal remiges) have remiges
which are shorter, sex for sex, than those of older
birds ( I lumphrey and Li vezey 1 982a, Li ve/ey and
Humphrey 1^86): Juvenal primaries of yearling
birds arc roughlv I .."^-2 cm shorter than those of
older buds, ami juvenal secondarv remiges are I-
l.'S cm shorter than basic secondaries, depending
on s|iecies and sex. Microstructure of remiges of
Tiiilncirs does not differ between flighted and
llightless species (McGowan I98M).

Several simjile ratios have proven especially
useful for distinguishing flightless Vi/c/nc/cv from
/. palachoniciis. This is generalh the diagnosis ol
greatest interest because the thice lliuhtless spe-

STEAMER-DUCKS {ANATIDAE: lACHYERES)

77

A

Fiy. 14. Caudal views of left mandibular rami of Tachycrcs. illustrating the variable medial inflection of the
proivssiis mandUndac mcdialis (slippled); A — essentially unintlecled process m 7 pauichoiiHiis (KL! 7i)2(l5l; B.
C — moderately inflected processes of / hraclixi'icni'.iKV S(l5hMand / Icinincplialiis (KU 77'-)_il ). rcs|icctively;
D — pronounced medial inllcclum of process ol 7 plcncics (KL' 74S42).

c

Fig. 20. Carpometacarpi of Tcnini-iv.s. lateral surfaces: A — T. patavhonicus (KU 1920^). B — /'. hnnhyplerus
(KLI S().'^27). C—T IciicoicpJialiis (KU 77Q25). D— 7. ptcncirs (KU 7')S42). Structures indicated: T— tuberosity,
disproportionately large in 7 bnu h\ptcni\ and T lciicincpha!us: F.A — the attachment site of W, cMcnsnriiwhuaipi
iihuiris (the "flexor" of Woolfenden l'-'61 i. progressively proxuiiatl to fornix in A — D; ST — the suit ii.\ iciidiuciis.
with pointed or bridged margins m 7 liiin hxplci ii.\ and / U-in m cphaliis: and TE — the comparati\el\ great caudal
extent of the trochlea m / plcncics.

cies are iiuitiially allopatnc and each may co- length or total mass). Except for relatively rare

occur with 7. pauichnnu us in marine litliiral en- instances of flightless marine T. pahuluinicus

vironments. Lamellar density, the ratio of lamel- (Himiphrev and Live/ey mS2b). wing-loadings (g

lar coLuil over bill length, ranks species and sexes hodv mass • cm " wing area) are informative: T.

inversely with respect lo body mass, and hence /)(//(/( /(((/(/(/(x Ivpically has wing loadings less than

facilitates separation of 7". palavlunuciis from 2. .■>; specimens of flightless taxa exceed this value

flightless Tiuhycrcs (Table 5). especially if used (Table .^). The ratio of wing length to tarsus length

in combination w ith a measure of si/e (e.g.. tarsus puis itics smii lar separation of the iwogiotips (Table

78

UNIV. KANSAS MUS. NAT. HIST. MONCXiRAPH NO. 8

Fig. 21 . Dislal ends of carpoiiietacarpi ofTcn li\cic.\. lateral surlaccs. showing the pointed niaignis ot'thc,si(/( m.v
tciulineiis (ST; .stippled) in 7 hniLlixplcius and 7 Iciicocepluiliis: A — T. palcichoniciis (KU 79205). B — T.
hruchyplciKs (KU 8().'S27). C— 7'. Iciu (n cphciliisiKV 7792.5 1. and D— 7. plciwrcs (KU 79S42).

Fig. 22. Distal ends of radii of Tachxcrcs. showing the comparati\el\ large, appressed seapholunar facet
(stippled) of T. lemocephcihis: A — T. patachmicus (KU 7920.5). B — /'. hraclnplcnis (KL' S()527). C — T.
Iciiioccpluiliis (KU 77938), D—T. pieneres (KU 79842).

,5, Fig. 24), IS measured iiioic easil>. and can be
used with study .skins. Roughly, the wings of T.
palachoninis are five titnes as long as their tarsi,
whereas the ratios of the flightless species average
four: sexual differences were insignificant. Murphy
( 19.'?6) gave the means for the reciprocal of this
ratio as: T pieneres. 0.26: T. hiiuhypienis. 0.24:
and / putdeluniicus. 0.20.

Multivariate analysis of a suite of external
measurements provides the most reliable discrimi-
nation of species and sexes (Appendix). Using the
fourmt)st commonly available skin measurements
(culmen length, nail width, tarsus length, ami
wing length) in a stepwise discriminant analysis.
71.4% of 245 specHiiens were correctly I jack-

knifed) classiHed to species and sex (Fig. 25): this
compares favorably to the 12.5% expected for
ranilom assignments. If sex is known, species
identifications using the same data achieved 91 .5%
success for males (« = 1 30) and 90.4% for females
(/; = 115), as compared to the random expectations
of 25%. This indicates that, for these characters,
knowing the se\ of the specimen improves accu-
racy of identilication by almost 20% . Inclusion of
total weight in the anahses reduced the sample
sizes and only slightlv impro\etl the success of
species-sex classihcations (79.4'/( success. /; =
131). C'lassitication functions incorporating the
four external measurements are gi\en in the
Appendix.

STEAMER-DLICKS (ANATIDAE: TACHYERES)

79

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STEAMER-DUCKS (ANATIDAE: TACHYERES]

81

T. patachonicus

T. I eucocep halus

T. br ac hypterus

I — I 1

2 CM

T. pteneres

Fiy. 2?. Dlai;i"aiii>- ol longest (ninth) prniiars and (Hitcmuist (tirsl) secondary remiges oi Icn hycrc.s. illiistratnig
I he Uinger. broader (light leathers of 7. paUu luiiiu lis: A — T.pahn limiu ii.s. male ( KU 7')4(il ): B — 7. Iciu at cplniliis.
male (Kl' 7'-)24fil: C— / hunhvplcnis. male iKV S()525): D— / piciwics. male (KU 7^)1X21.

82

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

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STEAMEK-DUCKS (ANATIDAE: IMHYKRIiS)

83

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r patachonicus T leucocephalus T brachypterus

66i57)

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C^C5,36, ??

(26)

SPECIES - SEX GROUP

Fij;. 24. Graphs of nie;iiis (horizontal lines), standard deviations (wide vertical bars), ranges (narrow vertical
bars), and sample sizes (//) for ratios of wing length over tarsus length for eight species-sex groups of Tachyeres.

40

2 0

<

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T brachypterus T I eucocephalus

00(I5)

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(61)

-26 -14 00 14

CANONICAL VARIATE I

56

Fig. 25. Plot of eight species-se\ groups of l\uh\cic\ on fust two canonical vanalcs ol lour external
measurcniciils; onl\ extreme inJi\iduaK ((.Iclimiling polygons) .nul means (asterisks) are plollcd.

Skimh At. Mea.slri-mhnts

few wing elenictits ami witlths of linih elciiiciits.

interspecific differences paralleled tiicsi/c rankings
Tw()-v\a\ .ANOVAs of -^6 skeletal diniensKMis of species produced b\ t(ttal binl\ weight, al-
(Table (ii demonstrated significant differences ihotigh magnitudes of the differences \aried among
atnong species (f < O.OOOI ) in all but sternal keel meastnements. Wing elements were iiuich more
depth (P > (1. 10); intersexual differences were similar in their lengths than would be |iredicted by
found in all measurements, males exceeding fe- overallbody size, evidently related to llightlessness
males m all {P < O.OOOI ). Except for lengths ot a in three of the species. .Actual reversal in interspe-

84

UNIV. KANSAS MUS. NAT. HIST MONOGRAPH NO. 8

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STEAMER-DLICKS (ANATIDAE: TACH)I:RI:S)

87

L'ilic rankings, wherein sni;ill '/'. pahu lumn us had
greater mean ineasurements than the laij;ci
flightless species, oeeurs in lengths ol the ulna and
radius. As a result, simultanedus eonsideration ot
sueh wing element lengths and a more si/e-re-
lated element (e.g.. sternum, femuri is et't'eetive
tor distinguishing 7. pauu lu>nu us from the
flightless species. Lowe ( 1434) illustrated the dil-
t'erence in relative lengths ot the humerus and
sternum between T. patavlumu us and 7. piciicics
(his hiavhypterus). Another anomaly occurs in
w idths of limb elements, in that T. Icucmcphalus
has consistently wider, more robust limb bones
than its larger relative T. hrachxpicrus (Table 6).
Overlap exists between species in all measure-
ments, but selected combinations of characters —
e.g.. ulna length, femur length, and humerus head
w idth — would be et't'eetive for species identirtca-
tion in many cases. A few of the measurements are
less reliable because they are influenced some-
what by age. even after fledging; sternal keel
length, sternal keel depth, and antorbital and
interorbital widths of the skull.

A particularly effective criterion for distin-
guishing T. putaclumuus from the three flightless
species is the ratio of humerus length to femur
length (Fig. 26). Flightless Tcuhycics have ratios
below 1 .6 and ratios for T. pahu haiucus lie above
Ihis \ alue; onl\ I skeleton in 148 violated this rule

(a male 7. Icuca cpiuilus had a \alue of exactly
I (il ). Mean values for this ratio are as follows: T.
ptikicluiuicus. I.6M; T Icuvovcphalus. l..'S.^; T
hi tn Inpierus. \ .52: I\ pieiwrcs. 1.47; sexual dif-
ferences within species were not signihcant (d.OS
< P<().7I ).

The relatively robust limb bones of T.
IcuKH cpliiilus are most clearly shown by the ratio
of the least width at the midpoint of the shaft
tli\ idetl by the length ot the element; limb bones
of r IciH lu cpluilus are either the most robust in
ihe genus (humerus, femur, tarsometalarsus) or
equaled only by those of T. piciwirs ( radius, ulna,
tibiotarsus). Except for the radius and ulna, these
ratios of robustness" are made more useful by the
lack of significant intersexual differences within
species (/'> 0.15: Table 7).

Another ratio useful for distinguishing T.
Icu( (Hcphalus trom other Tacliycrcs is posterior
sternal width divided by sternal basin length,
'sternal flaring" (Table 7). InterspeciHc differ-
ences in this ratio (log-transformed for ANO'VA)
were highly significant {P < ().()()() I ); intersexual
differences were nonexistent (P > 0.73 ). The com-
paratively great sternal 'flaring "in 7. Icimn cp/uilus
was noted qualitatively and illustrated in the de-
scription of the species (Humphrey and Thomp-
son 1981 ). Overlap between 7'. Iciuat cplnilus and
the three other species is minimal. L'sing 0.72 as

1.9

1,7

16 -

I 5

1,4

13

T potachonicus T. leucocepholus

T_ brachypterus

T. pfeneres

-i-ies HHies

<:^d(55) 00(46)

** -^153 -i-152

66{Z0) JJ(I7)

dd(l4) 92"2'

HH47 HI- 147

66{\B) JJ(I6)

SPECIES- SEX GROUP

Fig. 26. Graphs of means (horizontal lines), standard deviations (wide vertical bars), ranges (narrow vertical
bars), and sample sizes (/i) for ratios of humerus length over femur length for eight speeies-sc\ groups ot'Tachyeivs.

88

UNIV. KANSAS Ml S. NAT. HIST. MONOC.RAl'H NO. S

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STEAMER-DUCKS (ANAIIDAE: lACHYERES)

89

a di\ uliny \ aliic lor ihc ralm (sc\os pooled). onl\
4 ol }h (ll'() '/. U'liciHcplhilus tall hclow this
\aluc. vNhoreasonly 5 of 102(3'/( ) I .pahuluiiiuus.
2 ol 2fi (S'i ) T. hrmhypicnis. and 1 of 33 (39; ) /,
pli'iui'cs fall aho\c it.

Mulli\ariatc disLrimination of complete skel-
etons is exiremeh powerful (Fig. 27). Stepwise
canonical analysis, using 14 of 36 skeletal mea-
sLnenients, coiiectly identified the species aiitl sc\
of MS.S"^/ o\ 16.^1 ciMiiplete skeletons in jackknilcd
classitications; the two errors inclassilication were
small missexed specimens of '/'. paiiu iwnu ii\ and
T. hracliyptcms. Variables and classification coct-
ticients are gi\en in the Appendix. F-^ir fewer mca-
surenients arc needed to achieve classification
percentages approaching those for these "optimar
models (l-jg. 2iS). Classification percentages of
complete skeletons to species and sex exceeded
yO'r using only six measurements and reached
y.^' ( incorporating 10 variables. If sex is specified,
species identifications using optimal models were
completely successful for both males (;/ = '-)(!. I')
variables usetl) and females {n = 15. 10 variables
used). Limiting the analyses to single sexes per-
mitted greater reductions in the number of vari-
ables needed to classify. For males, species clas-

sitications were 97.S'y correct using onl\ two
measurements (lengths of the femur and ulna);
species identification of complete skeletons of
females reached 94. 7'; success using two mea-
surements (least sternal w idth and w idili >)t ulna at
midpoint ).

Partial skeletons. v\hich t\picall\ rcsiili from
preparation of stmh' skins or the salvage ot tlam-
aged carcasses, lack skulls and distal limb ele-
ments and are less successfully identified. Idenli-
licatioiiof 199 partial skeletons using 10 of the 13
available measurements was 91.7'/( correct. Clas-
sification functions are given in the Appendix. If
sex is known, successful identifications of species
increased to 96. 3"^; for males (;; = IO(X. 9 variables
incorporated into model ) and 100'^^ for females (h
= 91. 7 variables). As for complete skeletons,
much simpler combinations of variables are nec-
essary to achieve reliable classification of partial
skeletons of known sex. Determination of species
for males exceeded 9()Vr using only three vari-
ables, and surpassed 95% based on five measure-
ments (Fig. 2S). In jiarlial skeletons, only two
measurements (femur length and posterior sternal
width) were needed to achieve 95.6'/( success in
species classification (Fig. 2S).

H

6

UJ

1-

<

4

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CXMI6)

T leucocephalus

T. pat achonicus

-I L.

_l L

-10

-6-4-2 0 2 4

CANONICAL VARIATE X

10

Fig. 27. Plot of eight species-sex groups ofTtirliven's on first two canonical variates of 1 9 sl^clelal nieasiirLMiienls
only extreme individuals (delimiting polygons) and means (asterisks) are plotted.

90

UNIV. KANSAS MliS. NAI . HIST. MONOGRAPH NO. 8

100

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males

both sexes

I 2

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f emoles

_!_

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8 9 10

3 4 5 6 7 8 9 10 19 \ 2 ' ■• - ■

NUMBER OF VARIABLES INCORPORATED

Fig. 28. Classiticaliiin percentages lor increasing lumihers ol measurements available lor complete and partial
skeletons; analyses of males, females, and sexes combined are plotted separately, and terminal (ended) pt)ints ol
each curve reprcsenl optimal, backstep-selected motlels.

KEYS TO IDENTIFICATION OF SPECIMENS

Skins

Downy Yoi^nci

The followini; key, after that given by Humphrey
and Ijvc/ey ( IMS.^ I. is applicable to class-1 dov". nics
ami. perhaps, to earl\ class-il dounies retaitiiii!:
clear head patterns, t'haiacterisiic head patterns ol'
the tour species vserc ilkistratetl by lluiiipliivN atid
Livezey 1 1 48.^ ).

la.Uppcrcyelul \\ hitish; ctinvn tlarker than checks;
.supraloral ami supraoculai patches u idc and con-
tinuous \\ ith v\ idc jiostocular streak

/. IclK IK CplhllllS

lb. Upper eyelid tlark; crow n not darker than checks
2a.Postocuiar streak divided: supraloral ami

supraocular patches very small or abseiil. ami

scparalc uhen present T. picncrcs

2b.Postociilar streak uiidi\ided: supraloral and

sti|iraocLilar patches present .^

.^a.Supralor;il and supraocular patches very narrow

(almost occkkled anteriorly ). continuous, ami

separateil Irom postocular streak

T. paldchoniciis

.^b. Supraloral and supraocular patches narrow and

continuous with postocular streak

T. hnninplt'ius

F-i i:ix;rD Birds

.•\ge- telated changes in bod\ mass, colors ol solt
p;irts. ant! plumage pattern piechKle the presentation
ol qualitative ami mensural diagnostic keys tor skins

STEAMER-DUCKS (ANATIDAE: TACHYERES) 91

of fledged specimens o\ all species of Tinhycics. 4 kgand nail w idlh usLially 14 mm or less: limited

Accordingly. qualilati\ e chaiacieis in the ke\ gi\ en to coastal environments of C'hubut. Argentina or

below are representative only of adults indetinitne the l-alkland Islands 3

plumages, whereas mensural characters apply to 3a.A/(//c,v indistinguishable externally from 3b; fc-

birds of at least one year of age and not in wing molt. iiiukw \\ ith postocular streak becoming indistinct

posteriorly; endemic to the marine coasts of the

la.Ratio of wing length to tarsus length generally lalkland Islands T. hrachxplcnis

exceeds 4.."^; wing-loading usually less than 2.5 3b. A/<//c.n indistinguishable exlernally from 3a; /c-

g • cm -; imilcs ty pieally w ith body mass less than nuiles with postcKular streak typically biDad pos-

35()()g.winglenglhgreaterthan2^K)mm.andtail teriorh to whitish collar; endemic to marine

length greater than 10.^ mm: fcnialcs typicalh' coastal Chubut, Argentina T. Icuctn epiialiis

with body mass less than 27.50 g. wing length

greater than 280 mm. and tail length greater than Skki KTONS

100 mm; most males and all females capable of

flight; occurs throughout Fuego-Patagonia and la.Ratio of humerus length to femur length greater

Falklandlslands.includingfreshwaterandcoastal than 1.6; additional iiindal characters are medi-

localities T. patiulunucus all\ uniiiflected processus mandibulae medialis

lb. Ratio of wing length to tarsus length generally of mandible and attachment site of M. extensor

less than 4.5; w ing-loading greater than 2.5 g • metacarpi ulnaris on carpometacarpus opposite

cm-; iihtles typically with body mass greater proximal fornix of intemietacarpal space; occurs

than 3500 g. w ing length less than 290 mm. and in both coastal and inland localities throughout

tail length less than 105 mm; /(7?;(//(',v typically Fuego-Patagonia and tlie Falkland Islands

with body mass greater than 2750 g. wing length T. putuchnnlciis

less than 280 mm. and tail length less than 100 Ib.Ratioofhumerus length to feinur length less than

mm: both sexes incapable of flight; limited to 1.6; additional modal characters are medially

marine coastal habitats 2 inflected processus mandibulae medialis of man-

2a.Adults essentially without sexual dichromatism. dible and the attachment site of M. extensor

hath sexes ha\ ing a bright orange bill. gra\ head metacaipi ulnaris on carpometacarpus proximad

and neck, faint postocular streak, and lacking toproximalfomixof intemietacarpal space: lim-

extensive chestnut coloration on scapulars, sides ited in distribution to marine coasts of Fuego-

and flanks: ratio of wing length to tarsus length Patagonia and the Falkland Islands 2

generally less than 4.0; /))(//('.s topically with body 2a. Occipital condyle usually extends ventrad to

mass greater than 5 kg and nail width frequently basioccipital plate: caipal trochlea extends caudad

exceeding 15 mm; /('///(//('v typically with body to metacarpal III; sulcus tendineus of

mass greater than 4 kg and nail w idth frequently carpometacarpus w ith straight, parallel \\]-)s:inides

exceeding 1 4 mm; occurs in marine coastal habi- generally with femur lengtlis greater than 87 mm,

tats from central Chile south and east to Isladelos females with femur lengths greater than 82 mm:

Estados. Argentina T. pteneres limited in distribution to coasts of central Chile

2b..'\dults show ing sexual dichromatism. males ha\- south aiul east to Isia de los Estados

i ng distinctly lighter (often virtualK white) heads J, pietieies

and more orange bills than females; both sexes 2b.OccipitaIcondyleusualIy dorsad to basiiiccipital

have comparatively distinct whitish postocular plate: carpal trochlea does not extend caudad to

streaks; adults with substantial amounts of chest- metacarpal III; sulcus tendineus of

nut coloration on scapulars, sides, and flanks: carpometatcarpus typically with short, pointed,

ratio of wing length to tarsus length generally often bridging borders; males generally with

greater than 4.0; //;(//c,\ typically with bodymass femur lengths less than 87 mm. females with

less than 5 kg and nail w idth usually less than 1 5 lemur lengths less than 82 mm 3

mm; /(7//(//cA typically with body mass less than 3a. Ratio of sternal caiakil width to sternal least

92

UNIV. KANSAS MILS. NAT. HIST. MONOCiRAl'H NO. 8

vviciili usuall\ exceeds 0.72; scapholiinai- lacei ot
radius relatively large, appressed to shall; en-
demic li> coastal Chubiit. .Argentina

T. Iciudccpluiliis

.lb. Ratio ot sternal caudal width to sternal least
width usually less than 0.72; scapholunar facet of
radius not expanded; endemic tocoastal en\ iron-
ments ot the Falkland Islands.../, hnnhyptenis

FIELD IDENTIFICATION

Introductory Comments

The s|ieciesot'steamer-duck are so similar to one
another and ha\'e such a complicated array ot molls
and plumages that it remains very difficult to detini-
ti\ ely characteri/e any one of the species using only
field marks or external characters. Historically this
caused a great deal of trouble for museum taxono-
niists and continues to be a problem for field orni-
thologists who wish to make identificaliims without
collecting specimens. These difficulties have troubled
a number of ornithologists who have tell that it was
inappropriate to ilescribe a new species of flightless
steamer-duck (/'. Iciicoi ci'luihis) which, it was felt,
might more appropriately have been considered
simpl V a subspecies ofanolherpopiilatioiU)f II ight less
steamer-duck (e.g.. 1. piciicrcs or T. hrculnpicrus):
evidently the notion was. we judge, that "big" birds
that look alike and have allopatric distributions
cannot be ilistinct species.

In many respects, the crNjitic species of /<;(■/( \'(7c,v
are comparable in diflicult\ to tiie Eiupiil<ina\
flycatchers of North America, wherem identification
is best considered a specimen-based, not a field,
exercise. We suspect that there are several other
genera of large birds (e.g.. Fluiluvnivorax. Amis,
lininta) that iiicluile Liiulescribetl or unrecognized
species that are osteologically separable. re|ir(Hluc-
tively isolated, and biochemically distinct, but so
similar that, with museum skin specimens ;uul for
purposes <ilfieUl uleiUilic;ition. the niajoril\ of orni-
thological laxonomists are unwilling to recogni/e
them as sjiecies. Why this shouki be so for large birds
and not small ones like i.inpuloiMX. \ irco. Amliiis.
and many others (]irincipall\ jiasserinesl is not clear.

(iixen the close similarities of the four recog-
nized species of steamer duck, the best apiiroaeh to
their field identification is a geographic one. The
only serious problems with liekl identification are in
regions where two species may co-occur, lor the

most [xirt this is the case in marine littoral environ-
ments but may also be true in freshw aler ponds near
the seashore in Tierra del Fuego. the southernmost
regions of the continent, and the Falkland Islands.
Several references include illustrations of steamer-
ducks (Delacour 1954; Olrog 19.^9. I9S4; Scott
1972; Harrison 1983; Narosky and Yzurieta 1987),
but the most detailed and up-to-date are those
provided by Madge and Burn ( 1988). Fine illustra-
tions of both sexes, a bii\l in flight, and downy young
for /. piikniioiiiciis are given by FJeldsfl and Krabbe
( 1990: plates V. VIII). However, before discussing
field iiienl ificat ion of steamer-ducks b\ region, there
are several general problems to consider, i.e.. eco-
logical segregation, size and o\erall proportions,
;ind llightlessness as aids m liekl iilcntilication.

E(()i.o(;u AL Sk<;rk(;aii()N

Flightless steamer-ducks are liiifited to marine
coasts, except for infretjuent. short v\alks they may
make lo brackish and freshwater bodies near the
coast. The \ ast majority of flightless Tachycrcs are
encounteretl on the shores of bays and exposed
headlaiuls. ami are especiallv abumlant at riser
mouths and around offshore islands. Of the three
flightless species, only T. Iciicocepluihis is com-
moiil\ found on beaches with extensi\e tule flats.
Murph\ ( 19.^6:199) obser\ed that an "avoiiiance"
ol extensis e tide fiats b\ flightless T. ptcucrcs under-
lies its ;ibsence on the .Atlantic co;isl norlh ol lierr;!
del 1-uego. Rocky, rugged headlands, occasionally
interspersed with sandy and stoin beaches, and
Ikinkcd b\ bunch grass and brush, are more t\ pical
habitats of lacliycrcs (De la Pena I9S2:44; pers.
obs.). Breeding adults are seen most frequently in
pans along well delineti aiul defended segments of
shore (Murpli> h),^6. McWhan 19.^2. Wellcr 1976,
l.ivezey ami llumphre\ I98.^a). Intensive territori-
alit\, both intraspecilic and toward olhci species, is

STEAMER-Dl K'KS i ANATIDAE: TACIIYrRl S)

93

charaLtLTislic ol Iik li\cirs. the e\(iliilioiuM\ iiiipli-
calions ol w Inch ivniaiii cunlroxciMal (Livc/cs aiul
Huniplircy |yiS5a.b;Nuechteileinand.Sioicr I^S.^a.
b:Murray 19X5. I9S6: Live/ey 19S7a); MaLDimagh
( I'-MI )piesenlei.lanearl\ discussioiml icii iloiialil>
in Uiyhlcc! and tliyhlless hiclncivs. Nonbrcedmg
adiills aiul suhadiilt buds frequently are encininlered
ni laryc. otlcn e|uarivlsome tlocks near shorelines
not occupied b\ territorial pairs. All species ot
Tachxcrcs t'reqiientl\ di\e tor food (Weller l9A4a.
Livezey I "-'SSa I. and all t\ picall> nest on the ground
(Weller |y64b). although members iit several spe-
cies ha\ e nested in natural or human-made cavities
(lluniphre\ and Livezev 19S5).

Fl\ iiig Steamer-ducks are more \ aried in habitat
than their llighlless congeners. On marine coasts of
Tierra del Fuego and Chile. T pahuhanh iis occurs
more frequentK on open beaches than 7. pivneics.
which instead frequents rocky shores (Live/ey
19<SSa). In coastal Chubut. our tew records of /'.
pataclioiiiiiis were made in habitats heavily used by
the much more common T. Iciicuccpluiliis: the two
species iiilret|uentl\ occur in mixed Hocks. In the
F-alklaiul Islands. 7. piiiaihoiuvus co-occurs occa-
sionall\ \\ ith abundant T. hnuiiypterus on saltwater.
es|ieciall\ in w inter, but is believed to inhabit Iresh-
v\ ater ponds during the nesting season ( Weller I M72.
I47h). In addition. 7. pahichoiiiciis occurs on fresh-
water lakes, at least during the nesting season, Irom
Tierradel Fuego north to mountain lakes in \eue|iien.
.Argentina, and Region .\. Chile. Fjeklsa and Krabbe
1 1 '■^)( I ) reported the presence of flocks of nonbreeding
r. pahn lumuiis on large, often turbid, sometimes
alkaline lakes.

Gknkral Appkarancf.

All species ofTacliyeivs are comparati\ ely bulky
and thick-necked, and have liea\ y bills, largely gray
backs and sides, white bellies, and orange-vellow.
conspicuously large feet. The upper breast and sides
show variable amounts of brown. Both sexes have a
\\ liite speculum, which contrasts \\ iih the dark gra\
ot the rest o\' the wing, and a short or. in 7
piihii lionu us. moderately long, recurved tail. Dur-
ing the breeding season, heads of adult males are
substantialls lighter than their backs (largely white
in all but 7'. picncrcs). and are markedly lighter than
those of their female consorts.

In good light and at medium or short range, the
greater bulk. relati\el\ shorter wings, and shorter,
stiaightertailsof the flightless sjiecies should distin-
guish e.ich Irom the smaller, slimmer 7. /><//</( 7;(V)/(7(.v.
Pairs ol adult 7'. ptciwirs can be identitied immedi-
ately by the orange bills of hnili nude and female:
bills of females of other species in the genus are
much darker than those of their mates, with yelk)w-
orange being absent o\ limited to a small area near
the base. During the breeding season, adult male T.
pieneres are unique in having a silver-gray head
|ilumage. whereas the heads of breeding adult males
of the other three species are largeh w hite v\ ith gray
cap and cheeks. The head and neck |ilumages of
female T. pteiieres are decideill\ more gray than
corresponding plumages of females of the other
three species, and the postocular streak of 7. /V(7/(7('.v
IS typically less conspicuous. If comparison with
other waterfowl is possible — e.g.. sheldgeese
(t7//('(7)/;(/'.;(/spp. lor dabbling ducks (,\/((/.vspp.) —
the substantial size on'.pfcneres is readily apparent.
Even in Tierra del Fuego, where only T. pteiwres
occurs with 7. pa(a(. haniciis. species identihcation
in the Held can be challenging, and we encourage
observers to follow Eamshaw ( 197.i:2()S) in report-
ing sightings of steamer-ducks as simply ■''/(/< Vntvt'.v
sp." it conditions do not permit contiilent identihca-
tion to species.

Distinguishing T. pauu hmiu us from T.
leucin epiudus (coastal Chubut) or 7' hrui hypienis
( Falkland Islands i in the held is much more difhcult.
The shorter wings of the flightless species some-
times may be distinguished at close range, espe-
cially if the wings are stretched or flapped. The more
slender neck and longer tail of T. pakniuniiciis can
be evident under good field conditions, particularly
if the birds adopt the 'alert' posture in which the
back is arched and neck extended. L'nfortunately.
contrary to the belief of a number of local amateurs.
7. piitachiiuicus is indisiinguishable from 7".
hnichxpienis on saltwater, unless the lormci is seen
in flight (Matthews 1977: pers. obs.i.

Behwiok

Only T pahulioiucus is cajiable of genuine sus-
tained flight, although some males of this species are
permanentlv flightless in some marine localities

94

UNIV. KANSAS MLIS. NAT. IIIST. MONOGRAPH NO. K

(Humphrey and Livc/cy mS2b). Moincntary asccni
or short, descending, tlapping passages can be accom-
plished b\ all Ihrcc lliglilless species, especially if
aided by a strong head-wind ( l,ivc/cy and lhini|ihrey
1 ^)82 ). Wind conditions signilicanil\ altect the ease of
attaining llighl in T. pdUiclioiucus as well, even when
the birds are piirsued.Ohviously. steamer-ducks of all
species cannot lly when in wing molt, an event that
typically occurs during middle to late (austral) sum-
mer (llumphrc\ and l,ive/ey IM82a).

All species oiTachycn's 'steaiu.' the characteris-
tic, turbident method of surface locomotion for
which the group was named ( Livezey and Humphrey
U)S.^). In typical steaming, the head and neck are
drawn up and back, not extended forward as in a
take-off run of 7". paiachdniciis: Flying .Steamer-
ducks sometimes begin by steaming but later adopt
a take-off posture and take flight. Generally, the
three flightless species appear heavier than /
jhiuniioiiitiis while steaming antl evitlcntly are less
able to raise the breast above the water surface.
However, the larger species can steam quite rajiidly.
and for 1 km or more without rest, antl we ha\e
observed very buoyant steanungby /, hnniiyplcnis.
Giai ( m.'^l:2.'i6) likened the surface locomotion of
down_\ Brazilian Mergansers (A'/<'/',i,'((.v()(7f),v(7(;((7(.v)
to the steaming oiTaclnerc.s. but we doubt that this
comparison is valid in detail.

Steamer-tlucks also sw im and dive proliciently. the
latter being a commonly emplo\ed (and effective)
escape behavior (Live/ey and Humphrey 19S2):
steamer-ducks use wing-strokes at submergence but
typically do not use their wings for propulsion under
water (Johnsgard 1962. Live/ey and Humphre\
1984a). Terrestrial locomotion of steamer-ducks often
appears rather awkward; the birds are often obser\ eil
waddlingslowly from a loating site tow arti water u|ion
approach by an observer. When pressed, howexer.
steamer-ducks are capable of suiprisingly rajiid run-
ning for shot! distances, especially down inclined
shorelines toward the safety of w ater. w hich i\ pical 1\
is followed by steaming. tli\ing. or (in 7. /)(//</( 7/(»/;;(7(s)
flight. Sometimes T.paidi limiii ii.s takes flight tlirectls
from shore, particularly if the birds launch from an
incline and are aided by a heatl-w ind. Contrary to the
conclusion of Hebard (I9.'i9). at least 7'. ptciicrcs
occasionallycmploys "injury-feigning' (Live/ey and
Humphrey 1982).

V()( Al.l/AIIONS

The vocal behavior of steamer-ducks has re-
ceived a moderate amount of study, at least in
comparison to other anatids. probably because of
the associatit)n t)f most vocalizations with territori-
ality in racliycirs. Cunningham (I871b:96) hrst
noted sexual differences in vocalizationsof steamer-
ducks (species not given), describing that of the
male as "a sort of mew rapidly repeated" and that of
the female as "a kind of tieep growl." Moynihan
( 1 9.^8 ) described the calls of female 7. patm hoiiiciis
as "Grunts." short, moderatels loud, antl deep vocal-
izations gisen singls or repeated in \ariabl\ long
series. Mosnihan ( 19.^8) di\ided the higher, more
whistle-like calls of male r. /)(//t/( /;()/»( ((.s into three
types, in onler of increasing aggressiveness: "Sibi-
lant Grunts." "Ticking Grunts." and "Rasping
Grunts." Vocalizations of both sexes of T.
puiiK lioiiidis were heard by Moynihan ( 19.S8 ) most
frequently in territorial encounters between pairs,
during which the birds performed other "hostile"
displavs such as "False Drinking." "Stretches."
"Short -high-and-broad Postures." "Submerged
Sneaks." and "Head-flagging." MoMiihan
( 1 9,58:201 ) also reported that 7. prciicirs produced a
sinular diversits of \ocalizations under similar
sociobehavioral circumstances, but that both sexes
of I . prencirs "...uttered more complex (irunting as
well."

Woods ( 1 97."^: 121) liescribed three t\ pes of calls of
male 7" hnulixpierus: a "loutl \ ibratorv..."ch('('roo,"...
|a| more conversational. ..'cheeoo."... [audi a rapid
sharp "kek-kek-kek.' " The calls of female T.
hiiH lixptciiis as "...a short, guttural t|uacking note"
anil "...a peculiar low creaking note."

Weller (1976:50) rendered one call of male I.
hnninprcnis as "...a clear, high-pitched, rasping
whistle...sNllab\lizedas ■/)<■-( '«,'.;/;" or '/'<' c miiili' "
Weller contrasted the homologous call of male 7".
pwncics as "more sliuTcd" and regularK seeming to
have an extra syllable (s\ llab\ lized as "psc~c oiiiih"
or "/nc-r'-c-o;/'.,'/)"). and that of male 7. /)(;/(/< /(o/hVh.v
as "similar but higher pitched." Weller noted tftat
males of all three sjx'cies also utteivd more intense seines
of short notes, syllabyli/ed as "/x'u' pcw-pcw." He de-
scrilvd only the calls of females for 1. hnuhxplcnis.
which he tenueil "croakini: erunts" and rendereil as

STEAMER-DUCKS (ANATIDAE: TACHYi:Ri:S)

95

''•^niT-r.""{;iiiTk."":^iork-i;urrk-:^iirrk."imL]"i;i(iink-
!;/y>//;A-!,';v'/hA:"" he also altributed a cdiuunent "'click-
ing sound" to the female. Weller noted that paired 7
hnuhyptcnis \iKali/ed synchronously durini: terri-
torial defense, the males intensifying their calls in
tandem as hostilitiesescalated.Neuchterlein and Storer
( 1985) described such territorial "duetting" between
mated T. patavhoiiicus. and presented the first
sonogram ofvocalizationsforthe genus; this sonogram
depicted "Groans" and "Gmnts" by a lemale. antl
■"Rasping Grunts" and an extended bout ol '"Tickuig"
by a male.

Fjeldsa and Krabbe (lW():i:()) described the
vocalizations of territorial male T. paiavhonnus as
"...long series titididididi.... luiirr liuirr liiiirr.... hr-
hi-hr.... and engine-like toc-toc-toc... alternating
with loud whistled hzlicco. Also low cackling iiiii-
and kck kck. Calls Ikcc."

Vocalizations ol all four s|iecies ot liuhycics
were recorded in the tield by Roberto Straneck.
copies of which he generously gave to us. Conci.sely
summarized, most vocalizations of steamer-ducks
are associated with territorial disputes and therefore
are agonistic in nature. In all four species (F-ig. 29):
( 1 ) males give ""Rasping Grunts, "" descending, rasp-
ing calls which are comparatively lower in fre-
quency and prolonged in T. picncics: { 2 ) males often
follow ""Rasping Grunts" with bouts of ""Ticking;""
(3) females often duet with males (particularly dur-
ing bouts of ""Ticking"! with deeper ""Grunts." often
preceded by a few deep, more prolonged ""Groans""
(Nuechterlein and Storer 19S5). The vocalizations
of Tiichycrcs deserve special attention by future
workers, particularly with respect to behavioral ecol-
ogy and interspecific (.litferences.

STEAMER-DUCKS IN CAPTIVITY

Steamer-ducks are rarely kept in captivity, not
only because of their limited and comparatively
isolated distributional ranges, but also because of
their aggressive behavior toward a diversity of other
species. Livezey and Humphrey ( 1 ys.'^a) compiled a
number of records of such interspecific attacks by
steamer-ducks; additional targets of aggression by
captive Tacliyercs include a Rhea { species not given ).
Demoiselle Cranes {Aiitlinipnidcs viri;o). Tasma-
nian Native-hens (Trihunyx murticrii). and Crested
Screamers (Cluiuiui ron/iiuiu) (Griswold 1968.
Schmidt 1969). Todd (1979:162) recommended:
"Under no circumstances can these hostile ducks be
mixed with any wildfowl (or most other birds), as
they would kill them instantly, regardless of si/e."
He (p. 162) added, however, that '"...in spite of their
obvious temperamental shortcomings, most cap-
tive steamer ducks that I am familiar with were
extremely endearing." In addition to their aggres-
sive temperament, steamer-ducks do moderately
poorly in captivity, suffering significantly from
disease and proving difficult to breed (Hillgarth
and Kear 1979).

The first record of a capti\e steamer-duck was
one T. hrachypicnis presented by Captain T. Fi. L.
Moore to the VJenaizerie of the London Zoological

Society on 5 September 1861 (Sclater 1861. 1872.
1877. 1879. 1880b. 1883); this individual of un-
specified sex evidently lived for more than 20 years
in captivity. Nine more T. hnichypicrus were cap-
tured during the expedition by Captain Lecomte to
the Falklands during June 1867. but unfortunately
none of the birds survived a stonny passage between
Port Stanley and Montevideo (Sclater 1868). An
additional live specimen of T. hnuhyptcnis was
presented to the Menagerie in London by F. E. Cobb
on 12 June 1882 (Sclater 1882, 1883). A third and
evidently final specimen of 7. hnichyptcnts donated
to the Menagerie was presented by A. McCall on 23
June 1888 (Sclater 1896); based on the report by
1 1 ubbard ( 1 907 ). this individual survived for almost
20 years. These two instances of long-lived steamer-
ducks indicate that the datum on longevity tabulated
by Mitchell ( 1911 :5 14) for7(/(7m'/c,v — \> months —
was a substantial underestimate.

The Falkland endemic continued to be the most
trcquently acquired Tavhycics into the twentieth
century. S. Kemp and .\. G. Bennett arranged for
four specimens of T. hiiichxpicnis. captiued during
the "Disco\ery" expedition, to be gi\en to the Lon-
don Zoological Gardens (Seth-Smith 1927).
Heinroth (1929) noted the presence o\' "Tachyeres

96

UNIV. KANSAS MUS. NAT. HIST. MONOCiRAPII NO. S

>-
u

z

UJ

3

o
lu
cr.

T patochonicus

IK K n| fit

I I I I I I I

T brachypterus
A.

I

K

T 1 1 1 1 1 \ \ 1 1 [ \ 1 1 1 1 1 1 1 ^"'

17

«-, T I eucocephalu s

A.

B

iin

! I , 1 3-

1 M M n 1 1
\ • 111 I'll ( > I I I 1 I I 1'^

H X >: i H h

,_. T pt e neres

- A.
3- ^^^^

male

female

/A

,i^

1 ( i

> .r,>

j^j:^

i^ta

_L-I_

-1 — p-^'-'T

mole female

,1 I .1 I I 'I

•!!!

\ ' ■' fc^i

kn^mk.

...^\\\\\\\\\:- 'f^ f^ ^

Fig. 29. Sonograms of Tachyeres based on recordings made in llie liekl by R. Stranect.: T. pcikichoniciis — (A)
"Rasping Grunts" by male (Bahia Lapataia. Tierra del Fuego. Aigeniina. January 19SI ). (B) "Ticking" by male
(l.aguna los Escarchados. Sania Cru/., Argentina, November 1981 ), (C) "Cirunls" by female (Laguna la Nevada.
Santa Cruz. Argentina. November 19S1); 7'. piciwics (Bahia Lapataia. Tierra del Fuego. Argentina. January
1981) — (A) duelled "Rasping Cirunts" by male and "Grunts" by female. (B) duetted "Ticking" by male and
"Grunts ■ by female; /, hnu liv/ncnis (Carcass Island. Falkland Islands. December 1978) — (.A) "Rasping Grunts"
by male. (B) "Ticking" by male; /, iciiviHcphaliis (Fuma Tombo. Chubut. .Argentina. November 1982) — (.A)
"Rasping Grunts" by male. (B) "Ticking" by male. (C) '(irunl^ ' by female (in distance).

(•//u'/c/rs" al the Foinlon Zoo. ;iiul Dclacoiu ( 14.^4) U.).^2). bill il (.IkI not survive (,\non\moiis 19.^1.

reported that Ihrce pairs ol"/ /'/!/( 7;\/)/(77/.v reached Sladeii I'J.'S^). Spcciniciis of /. hnnhypicnis ac-

Englandiii 1928. oneof which vvassenltotheaviary quired during the next decade (e.g.. .'Xnoiiynious

at Cleres. France, by .S. Lewis and where the birds 1957. Johnstone 196S) led to successful breeding in

hvedforsevenyears.Anolherlemale7./)/<;(7n7)/('y((\ captivity at zoos in Duisbuig. Cicniiany (Ciewalt

was brought to the Wildfowl Trust. .Sliinbridge. 1968). Zurich. .Switzerland (Schmidt 1969). and the

England, by W. J. L. Shuien (.Xnonyinous 19.50. Wildfowl I rust, lingland (Johnstone, pcrs. conim.

STEAMER-DUCKS (ANATIDAE: lACHYERES)

97

1 1 9(i,S I /;</(> Schmidl l^^; Jiihnstonc 1470). The
ducklings hatched at the Zurich Zoo were though! lo
be possible hybrids between T. ptcncrcs and /
hnichyptcrus. but errors in the plates by Scott in
Delacour (1954) appear to have caused the contu-
sion (Schmidt 1969): no hybrids among species of
Tachyercs are known (Scherer and Hilsberg I9,S2).
Efforts to breed T. hnichypterus have continued ai
the Wildfowl Trust for more than a decade since.
Willi variable success (.Anonymous 1973. 1974.
197S. 19S2. 1983. 1984. 1985. 1986. 1987, 1988;
Kear 1974. 1976. 1978: Lubbock 1979. 1980. 1981).
A female 7 hnichyplcnis held at Sea World. San
Diego. California (Todd 1979). was the subject of
study of diving behavior in Tachyercs (Livezey and
Humphrey 1984a) and appeared in a program on
flightless birds entitled "Birds of Paradox" pro-
duced by the British Broadcasting Corporation.

The Magellanic Flightless Steamer-Duck has
occurred even less frequently in avicultural collec-
tions, although T. piencres were kept in captivity for
use as decoys by Fuegian natives ( Bridges 1 948: 1 03 ).
Morrison (1940:249) mentioned his involvement
with a "collection of live Kelp— Geese {Chlocplur^a
liyhrulii]. Steamer-Ducks, and Penguins" during a
visit to southern Chile. T. ptcncrcs was listed as a
"needed" species at the Wildfowl Trust during the
1950s (Anonymous 1950. 1958). Delacour ( 1954)
reported that two T. ptcncrcs were brought to his
aviary at Cleres in 1939 by A. Morrison from south-
ern Chile (see Morrison 1940): one died soon after
arrival and the other "...was in excellent condition
until the invasion of June 1940" (Delacour 1954:273).

In .lul\ 1962. the Philadelphia Zoo received an
"immature" male T. pteneres. and an "adult" temale
ol the same species was acquired in January 1964:
these birds were successfully bred in 1967 (.'\nt)ny-
mous 1967. Griswold 1968). Additional live speci-
mens of steamer-ducks identihed as T. ptcncrcs
w ere acquired by the WuppertalerZoo. Berlin ( Bock
1973). the Wildfowl Trust (Kear 1977: Anonymous
1978. 1983. 1985. 1986. 1987:Lubbock 1979. 1980).
Sslvan Heights Waterfowl. Scotland Head. North
Carolina (J. Ballance. pers. comin. ). and the Detroit
Zoo. Michigan ( T. Schneider, pers. comm. ). There is
some doubt about the species identity of the captive
"7". ptcncrcs" in American collections: photographs
of the birds in North Carolina indicate that they are
instead T. hnichyptcrus.

Not surprisingly, the recently described T.
Iciicovcphahis of coastal Chubut. to our know ledge,
has not been kept in captivity. It is more noteworthy,
however, that the most widespread member of the
genus, T. patachonicus. also has never been ac-
quired for avicultural collections (Delacour 1954),
although the statement of Hillgarth and Kear
( 1979: 142) that "...Tachyercs patachaniciis has not
bred I in captivity]. .."suggests otherwise. The greater
mobility of the Flying Steamer-Duck probably has
enabled it to elude capture more easily. It also seems
likely that the absence of T. patachonicus from
aviaries, especially during the early collecting expe-
ditions to the Falklands in the late nineteenth cen-
tur\. contributed to the widespread reluctance by
taxonomists to accept the existence of a flighted
species of Tachyercs.

PROSPFXTS FOR THE FUTLRE

At the time of this writing, populations of all four
species of Tachyercs appear to be secure. T. ptcncrcs
and / hi ai hxpicrns are particularlv numerous
throughout much of their respective ranges, al-
though the former has become uncommon in the
northernmost parts of its range iChiloc and northern
Bahi'a de Ancud). The comparativelv w idespread T.
patachonicus is decidedly less common than its
Mightless congeners in areas of svmpatry. aiul the
status o\ T^ patachonicus in the Falklaiul Islaiuls is
inadequatel V know n. In one respect, the broad distn-
bulional range of T. patachonicus renders it less

vulnerable to threats to its continued existence.
However, until the population structure and possi-
blv underappreciated taxonomic complexities of 7".
/)(;fc;(7;(Vi;(7/.v are better understood! Li ve/cN 1986b.
Corbin ct al. 1988). the possible threats to its differ-
entiated, possibly reproductivelv isolated compt)-
nents cannot be assessed.

The species of steamer-duck tleserv iiig the most
vigilant monitoring is T. Icucoccphahis. This spe-
cies IS not onlv the most recently described mem-
ber of the Anseriformes. it also has one of the most
resiricled distributional ranucs of anv continental

98

IMV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. S

species of w alert owl. The \ ulnerabilily ol /
Iciwoccpluilus is niagnilied b\ its Hightlessness.
non-migrator \ habits, aiui strictly coastal distribu-
tion. At present, the population otT. Icucinephalus
appears stable and. at least locally, the species is
abundant. .Shipping and coastal oil retineries. ht)\v-
ever. are increasingly common acti\ ities in coastal
Patagonia, and the threat of oil spills to coastal
birds is substantial. In tact, oiled seabirds and
signiticant associated mortality already have been
observed in C'hubut (Jehl 1975: pers. obs.l. A
single major oil spill in Chubut could directh
threaten a signiticant proportion of the total popu-
lation ol"/'. Icniin cpluiliis and endanger its benthic

food SUJiplN.

A number of compelling problems remain con-
cerning the ecology and evolutionary morphology
of steamer-ducks. Basic data are lacking on the
migration, winter distributions, and possible repro-
ductive isolation of T. pakiclioiilciis breeding on
freshwater lakes. Even less well known are the 7'.
paiaclioiiiciisodhe Falkland Islands: the few avail-
able specimens and geographic isolation suggest
that this insular population has differentiated mor-
phologically from its continental counterparts and
may be deserving of species rank. Although some
headv\ay has been made in the study of the molts
anil plumages of steamer-ducks, much remains
unknown: particularly poorl\ understood are the
predetinitive plumages of all species (particiMarly
of 7. /)/c/?('/c.v) and the evident geographic variation

in the aspects and possible number of definitive
plumages of 7. pani< liDiiiciis. Our understanding of
Hightlessness in Tachycrcs would be improved sig-
nificantly by a quantitative study of the ontogeny of
the hod>' and pectoral girdle in yomig of known age
in both flighted and flightless steamer-ducks.

The extreme territoriality of steamer-ducks pro-
\ides an unusually promising opportunits tor the
stutlv of thisecologically important beha\ ioral phe-
nomenon, the implications of which remain contro-
versial (Live/ey and Humphrey lys.'ia. b: Murray
liJS.S. 1986: Neuchterlein and .Storer 19S.5a. b:
Live/ey IMSVl. Particularl\ intriguing questions
concern the temporal ami spatial stabilit\ of territo-
ries (especially in tidal habitats and near islands
with high nest-densities I. the ecological and evolu-
tionary implications of interspecific aggression, the
ontogeny, sexuality, and seasonality of territoriality,
and the impact of territorialilN on population densi-
ties and dispersion. The open habitat, low mobility,
extreme pugnacity, and conspicuousness of steamer-
ducks, especially flightless species, and sexual and
age-related differences in plumage aspect, make
steamer-ducks particularlv appropriate subjects for
the stud\ of territorialit\. The tameness and abun-
dance of 7, hiiit lixpUTiis. and the likel\ ease with
which both sexes could be attracted into live traps
for marking by playbacks of calls ( VVeller 1076) or
ilecox s. qualif \ this species as probably the opti-
mal member of the .'Xnseri formes f(M' the stutl\ of
territorialitv.

SUMMARY

A systematic review of the four species of
steamer-duck {'I'achycirs). a genus of benthic-di\ -
ing tadornine waterfowl limited in distribution to
southern .South America, is presented. Four species
are recognized: Flying Steamer-Duck iT.
piiniclionicii.s). Falkland Flightless Steamer-Duck
(7. hiachyptcrus). Magellanic Flightless Steamer-
Duck (7'. pii'iicrcs). and White headed Flightless
Steamer-Duck (7'. Iciicovcphaliis). The monograph
has six major objectives: ( I ) to present a history of
study of the genus: (2) to provide generic and
specific synonymies and species accounts: (.^) to
describe the molts and plumages of steamer-ducks:
(4) to present diagnostic characters and keys for

identification: (.5) to summarize infomiation on field
iiientificalion anil a\ iculture of 7<;(7;v(V<'.v; and (6) to
present an indexed bibliography for the genus.

The ornithological history of the steamer-ducks
spans foiM' centuries, and is divisible into four major
periods: ( 1 ) carl\ descriptions by e\iilorers and
natiualisis ua. I.'>82-18.''()): (2l debate concerning
the existence of Hying and flightless species in the
genus ( IS.^l-l').^.^): G) recognition of two (conti-
nental and Falkland) flightless species and a Hying
species ( 1 9,^6 l')7^)): and (4) discovery of a second
continental flightless species ( 1 ^80 to pieseni ). The
taxononnc histoiN of the genus reflects, in part, these
changing |ierce|itions. further comjilicated by de-

STEAMER-DUCKS (ANAIIDAE: TACHYERES)

99

h;itc coiKcniiiig ihe placcnK'iit of liichycirs within
the taniil\ and nonK-nclatural (.oiiliision ( in\(il\'iiii;
2? dittLMvnt binoiiiina in seven genera, evcluding
misspellings). Complete synonsinies ate given tor
the genus ami inehided species, with concise de-
scriptions of diagnostic chaiaclers and distribu-
tional limits and designation of types. Common
names in 12 languages are also given.

Knowledge of the molts and plumages of steamer-
ducks remains far from complete. History of study
of molls antl plumages of '/(/(/ncrc.v is divisible into
three eras, closely associated v\ ith changing percep-
tions of Ihe systetnatics of the genus: ( I ) era of
exploration (prior to I8.M)); (2) era of taxonomic
controversy ( 1X30-1 M.^^); and (3) era ot Murph>
( 1936 to present).

We niterpret a\ ailable information as supportive
of se\eral important hndings: ( I ) /. hnicliyprerus
and coastal Fuego-Patagonian T. paliic/uiniciis{nnL\
probably other populations of the latter) have three
molts and plumages per annual cycle, whereas, 7
ptcncics and'/". Icucaccphaliis have only tw(x (2)
basic pkmiages of the heael and neck in 7'.
hnichypicriis and 7". pataclumuus (and probably i.
piciicrcs)nK sexually monochromatic and resemble
the Juvenal pliunage, and that of 7. Iciicai cpliuliis is
sexually dichromatic wherein the female resembles
the Juvenal plumage: (3) definitive plumages are
attainetl dining molt II in Atlantic-coastal T.
patac/ioniciis and (probably ) T. hiinliyptcnis. those
of 7'. IciuiHcplkiliis may not be attained until molt
IV, and the age at attainment of dehnitive plumage
in 7. ptcncics is unknown. Detailed descriptions of
natal. Juvenal, and definitive plumages are given for
both sexes and all four species oi'Tachycrcs. empha-
si/ing topics for which information and specimens
are inadequate forconhdeni interpretation.

Diagnostic characters of steamer-ducks incliale
massive body proportions, colors of pliunage and
soft parts, and Hve skeletal characters. .Species of
liicliycrcs are distinguishable b\ a \ arietx of charac-
ters of plumage pattern and skeleton, most notably
by selected ratios of external and skeletal dimen-
sions (e.g.. ratio of wing length to tarsus length, or

ratio ol humerus length to lemur length). Multivari-
ate discrimination of species and sexes is jiossible
using discriminant functions based on suites of
external or skeletal measurements. Keys to sjiecies
of /"(/(/ncTc.s are presented, but idenlilicationof skin
specimens of subadull birds ot unknown sex and/or
locality may be problematic.

Problems oftieldidentihcation of steamer-ducks
essentially reduce to distinguishing the smaller.
v\ itlespread T. pataclumiciis from each of the mutu-
ally allopatric. marine-coastal, flightless species
that also occur on inland lakes (more than 1 km from
the coast). In coastal Chile and Tierra del Fuego.
( adult ) 7". ptcncics are unique in their large si/e and
the orange color of the bills of hotli sc\cs. Distin-
guishing T. patachoncius in the held from the two
intemiediate flightless species — T hiaclnpicnis
(Falklands)orr. lcuc(iccpluili<s(.coi\sVd\ Chubut) —
is difhcult: distinguishing T. pataclunncus from T.
hicicliyprcrtis on marine coasts of the Falklands is
probably not possible under most Held conditions.

Steamer-ducks have been kept in captivity infre-
quently, but cause difhculties in aviaries because of
their pugnacious behavior toward other waterfowl
and have proven moderately diftieult to breed. The
most frequently held species, both historically and
at present, is T. hracliyptcrns.

Wild populations of all four species ol7(a7;y(;'/cv
appear secure, although local declines in numbers
and threat posed by oil spills to marine populations
(particularly T Icncincpluihis) Justify efforts to
monitor and protect selected populations. Important
siibiects for future study include: the dynamics,
migration, and possible genetic fragmentation of
populations of T. patachonicns (especially the
Falkland population); basic information concerning
the molts and plumages of freshwater T.
piiiiii linnicns. T. Iciicoccpliiilns. and (especially) T.
ptcncics: and the evolutionary implications of the
extreme territoriality of the members of the genus.

The published literature on the genus — one that
spans four centuries and comprises over 550 refer-
ences— is summarized in a subject-indexed bibli-
ography.

RESLIMEN

Sepiesentaunarev isionsistemalicade lascuatro aves acuaticas, conociiios como tadorninos
especies de pato vapor (.Tciclivcrcs). iin genero de biiceadores benticos cuya distribiicion esta

100

UNIV. KANSAS MUS. NAT. HIST. MONCKiRAl'H NO. 8

restringicia al cxlrcnu) siir dc America del Siir. Se
reconocencuatroespecies: HipatdNaporvohKloiM/.
/wW(7((*//y(«.v), el palo vapor no voladorde Falkland.
('/'. hrcuhypicnis). el pato vapor no voiador
magallanico ( 7'. ptciicrcs ). y el pato vapor no voiador
de cabeza blanea ( I', k'ncm cpluilus ). Esia nionograt I'a
tiene .seis objetivos principaies; ( i ) presentar ia
historia del estudio de este genero: (2) proveer
sinoniniias geiiericas y especi'ticas y suniarios
iiilorniaiivosde iasespecies; (3)describiriasniudas
y pluniajes de los palos vapores; |4) presenlar
earacteresdiagn()sticosyelavespara ia iiientilicaeii'in
> avicullura de Tachycrcs: y (6) presenlar un indiee
bibliogratico del genero.

La historia ornitoiogiea de ios patos vapores se
e.xtiende por ciiatro siglos. \ se la puede dividir en
CLiatro periotlos principaies: (1) las prinieras
descripciones de expioratiores y naturaiistas (cerca
a 1.^X2- IS.^O): (2) el debate concerniente a la
exislencia de especies voladoras y no voladoras en
el genero ( iS.^2-19.^5);(.^)elreconociniieni(uleclos
(continental y de las islas Falkland |MaKinas|)
especies no voladoias y una especie volailora ( I ^)36-
1979): y (4) el descubrimiento de una segunda
especie continental no voladora 1 19S()-presente).
I, a historia taxononiica del genero relic [a. en parte,
esle panorama cambiante que es comiilicatlo aim
mas por el debate sobre la asignacion de iiniixcrcs
ilentro tie la lamila y conl'usiones de nomenclaluia
(relacit)nailasa2.^binomialesdirerentesen7generos.
excluidos los eirores ile escritura). .Se presentan
sinoniniias complelas para el gt'nero y especies
incluidas. con descripciones concisas de los
caracteres tliagnosticos. limites dislribucionales y
designacion de tipos. .Se proveen nombrcs conumes
en 12 idiomas. Fl conocimientt) de las mudas y
pluniajes de los patos vapores dista todavi'a de ser
coinpleto.

La historia tlel estudio de mudas y plimiaje de
7(/</;y(T('.vse lapuededi\ idiren 3eias.cercanamenlc
asociadas con las perce|iciones cambianics de la
sitemalica del genero: ( 1 )eradeexploraci(')n (pre\ ia
a lS.i()); (2) era de controversia taxomimica ( LS.^O-
\'-)?<?<): y (3) era de Murphy ( 1936-presenle).

I.ainrormaciondisponihlelainterpretamosconio
soporte de algunos im|iortantes halla/gos: ( 1 ) 7'.
hidcliypicru.s y 7'. pdiiiiiiiniiciis de las costas de
Tierra del Fues:o \ tie la Patauonia .Argentina (\

|irobablemente olras poblaciones de esle lillimo)
lieneii 3 mudas y pluniajes por ciclo anual. mienlras.
I .picncrcsy I . Iciiiincpliii Ins iKnen solameiiletlos:
(2l los pluniajes basicos de la cabe/a y el cuello en
7. hiavhyptcius y TpiiitK liniiictis (y probablemente
7. ptcncics) son sexualmente monocromalicos y se
parecen el plumaje Juvenil. y aquel de T.
IctiiiH cpluilus es sexualmente dicromatico y en el
que el plumaje de la liembra se parece al plumaje
juvenil: (3) pluniajes ilelinitivos se lograii en la
muda II en 7. p<iki(iiiiiiu iis tie la cosia allantica y
(probablemente) 7. hnn lixpicnis. aquellos de T.
Icucoccplhiliis tal \e/ no se logren hasta la muda IV.
y la edaii a la quu T. piciicirs alcan/a el plumaje
tletinilivo es desconocida.

Descripciones tielalladas dc pluniajes naiales.
juveniles, y ilelinitivos se dan [xira aiiibos sexos y
para las cuatro especies de Ten liycrcs. y se ent'ati/an
aspectos para los cuales informacion y especimeiies
son inadccuailos para inlerpretaciones correctas.

Los carateres disagnoslicos tie los paltis vaptires
incluyen proporciones del cuerpo graiitles. colores
tlcl plumaje \ partes suaves y cinco caracteres del
esqueleio. Las especies de Tachycrcs stin
disiinguibles poi' una variedad de caracteres de
jialron plumaje \ esqueleio. mas ntUablemente por
jiroporciones seleccionadas de dimensiones
exlcrnas y del esqueleio (e.g.. proporcii'in de la
longiiutl tlel ala sobre la longituti del larso. ti
proporcion tie la longilud del humero sobre la
longiiud tlel lemur). Discnmmacitin mullivariada
de las especies y sexos es posible con el uso tie
luncioiies tliscriminantes basadas en un eonjunio
de medidas tlel esqueleio y exlcrnas. Se presentan
claves [laia la itlenliticacitin de las especies de
lacliycrcs. pero la itlentilicacion de pieles de
espeei'meiiestleavessubatlultasdesexot) local idad
tiesconocitia puede sei' problematica.

Los problemas de uieniilicaciiin tic los palos
vapores se retlucen a tlistiiiguir al petiuehti y
amjiliameuie tlisiribuitlo 7. palachonicus tie cada
una de las muluamcnlc alt>patricas especies no
\ t)ladoras de la cosia marina t|ue lanibit-n ocurren en
lagos tierra adeniro (mas de 1 knule lacosta). V.n las
ct)sias de Chile y de Tierra del Fuegt). (adullos) /'.
ptcncics son unicos por su taniant) grande \ el color
iiaranja de los picos en ambos sexos. La tlisiincion
en el campo tie 7. pdiacliDniciis de las dos especies

STEAMER-DICKS (ANATIDAE: IMHMiRES)

101

no Mikuloras inicrmcdias — 1\ hiachxphiiis (islas
I-alkland | Mah iiias] )o T. Icindccpluilus (C'luihiil do
la cDsta) — es dilicik y distinguir T. palaclunuciis de
T. hrailixptcnis en las costas marinas dc las islas
I-alkkuul (MaKinas) prubablcnicntc no es posiblc
en la niayona dc cHindiciones dc canipo.

Los patos vaporcs no ban sido nianlcnidos en
cauliverioeon rrecucneia.pucspresenlantlilieiilladcs
en los aviarios debido a su eomporlanilenlo bel ieoso
liacia otras a\ es acLuitieas y al parecer sii repioiluee ion
cs dil'ieil. La espeeie mantenida eon mayor
I'reeueneia. hisiorieamenie \ al presenle. es l\
hicuhxpicnis.

F\)blaeiones sahajes tie las euairo espeeies de
Tacliyercs al pareeer eslan segLiras. a pesar de que
declinaeiones locales en iHimert)s v la amcnaza

lalenlc por derramamienios tie pelroleo a las
poblaciones marinas i parieularmenlc T.
/(■/((■('(■(■/'//(//h.v) justitican est'uer/os para monilorcar
y proteger a las poblaciones. Aspcelos imporianics
para cstudios t'uturos inekiycn: la diinimica.
migraeion. y posible t'ragmentacion genelica de las
poblaciones de T. patiuiuniicits (en especial la
poblacionde islas Falkland I Mai villas]); intormacion
basica concemiente a la muda y plumajes de T.
patcichonicus. T. Icucoccplialiis. y espccialmente T.
ptfiu'ics: y las implicaiones evoluiivas de la ex-
trema territorialidad de los miembros del genero.

La literatura piiblicada sobre el genero — que se
extiende por euatro siglos y comprende mas de 550
ret'ereneias — se resume en un indice bibliognitico
lematico.

SPECIMENS EXAMINED

•Specimens examnieil inthisreseaicli. w Inch num-
bered almost 500. are of several lypes (SN = study
skin. SK = skeleton. SK* = skeleton for which
exlernal data were recorded. SN/SK = skin and
partial skeleton. AN = anatomical or spirit speci-
men): when determined, sexes are indicated (M =
male. F = female); sexes gi\en in brackets were
determined by measurements and/or plumage.
Downy young are marked by "d" and birds in
Juvenal pliuiiage are indicated b\ "j."

InstitLitions holding the specunens are indicated
by abbre\ iations immediatel\ preceding the corre-
sponding specimen niMiiber(s). and arc as follows:
AM = American Museum of Natiual History, New
York; BK = Museum of Vertebrate Zoology, Univer-
sit\ of California. Berkeley. California: BM = Brit-
ish Museum ( Natural History ).Tring. Hertfordshire,
England; CM = Carnegie Museum of Natural His-
tor\. Pittsburgh. Pennsylvania: CR = LJni\'ersitets
Zoologiske Museum. Copenhagen: FD = Field
Museum of Natural History. Chicago. Illinois; HA =
Museum of Comparative Zoology. Harvard Llniver-
sity. Cambridge, Massachusetts; IS = Iowa State
LhiiversitN. Ames. Iowa: KU = Museum of Natural
Historv. L'niversitN of Kansas. Lawrence. Kansas;
LA = Los Angeles County Museum of Natural
History. Los Angeles. California; MI = Museum of
Zoology. University of Michigan. Ann Arbor. Michi-
uan: MA = MiiseoArszentinodeCiencias Naturales.

Buenos Aires, Argentina: NM = National Museum
of Natural History. Smithsonian Institution. Wash-
ington. D. C; PH = Philadelphia Academy of Sci-
ences. Philadelphia. Pennsylvania: R(3 = Royal
Ontario Museum of Natural History. Ontario.
Canada: RS = Royal Museum of Scotland,
Edinburgh: SD = San Diego Museum of Natural
History. San Diego. California: SW - Southwestern
College. Winrield, Kansas: YA = Peabody Museum
of Natural History, "^ale Lnixersiiy. New Ha\'en.
Connecticut.

Tachyeres patachomcl's (222)

Argentina

RioNc,!iro.— BM 9Q. 1 .27. 10(SN. M). FD (origi-
nally Princeton) ■•8847'" (SN. M).

Wc/«//k'/;.— LagoNahueIHuapi:BM99.1-27.10
(SN. M). MA l47Sa (SN. M), MA 31523 (SN). MA
36363 (SN. M). Lago Lolog: MA 35051 (SN. F).
Zapala. Laguna Blanca: MA 49987 (SN. F).

Cliuhui.— Puerto Melo: SW 3532/KU 77940
(SN/SK. M). KU 79450 (SK. M). KU 79479 (SK.
F). Rio Pico. Lago No. 3: MA 52486 (SN, F). Lago
Fontana: KU 79468 (SN/SK. M). KU 79469 (SN/
SK. F). KU 79470 (SK*. F). KU 79471 (SK*. M),
KU 79472 (SK*, F), KU 79473 (SK*, F). KU 79475
(SK*. M). KU 79476(SK*. F). KU 79477 (SN/SK),

102

UNIV. KANSAS MIJS. NAT. HIST MONOGRAPH NO. X

KU 79478 (SK*. M). BK 42829 (SN. M). BK 42S3{)
(SN. F). BK 42831 (SN. F). Lago Kiiigger: KU
79474 (SK*. M ). Arroyo Verde: FD ••24()4" (SN. F).
FD ■■24().5" (SN, M), FD ■•24()6" (SN. M). Cholila:
MA (Liiicalaloged. Kovacs No. 77) (SN. M).

Saiua Cm:.— Puerto Deseado: SW 3.'i35/KlJ
77944 (SN/SK. M). SW 3.'^36/KU 7794.'S (SN/SK.
F), SW 3537/KU 77946 (SN/SK, M), KU 77947
(SK, F), KU 77948 ( SK, M ), KU 77949 ( SK, F), KU
779.'S0 (SK, F), SW 3538/KU 77931 (SN/SK, F),
KU 779.32 (SK, M), KU 77953 (SK, F), SW 3.3.W/
KU 77954 (SN/SK, M), SW 354()/KU 77955 (SN/
SK. F), KU 77956 (SK, F), KU 77957 (SK, M), KU
77958 (SK. M). KU 79209 (SK*. F). KU 79210
(SK*. M). KU 79211 (SK*. M, j). KU 792 12 (SK*.
F), KU 79213 (SK*, F). KU 79214 (SK*, M), KU
79215 (SK*, M), KU 79216 (SK*, M), KU 79217
(SK*. F), KU 79218 (SK*, F), KU 792 19 (SK*, M),
KU 79220 (SK*, M), KU 79221 (SK*. F). KU
79222 (SK*. F). KU 79227 (SK*. F). KU 79228
(SK*.1VI).KU 79229 (SK*.F).KU79230(SK*.M).
KU 79231 (SK*, M). KU 79232 (SK*. F). KU
79233 (SK*. M). Ml 157719 (SK. M). NM 5.M266
(SN. M), YA 6400 (SK, M), YA 82326 (SN, F), YA
82327 (SN, F). Ri'o Santa Cruz: MA 52297 (SN. M).
Bahi'a de los Nodales: SD 38353 (SK. F). Rio
Gallegos: FD '•4697" (SN. M). PH 81 103 (SN. M).
Lagiina de lo.s Escarchados: CP791 (SK. M), Ml
220945 (SK. F'. d). Lago San Martin: MA 4288a
(SN.j). LagoRoca: KU 79459 (SK*. M). KU 79460
(SK*. M).KU 79461 (SK*.M).KU 79462 (SK*.F).
KU 79463 (SK*. M). f\Miio Me)reno: KU 79464
(SK*. M). KU 79465 (SK*. F). KU 79466 (SK*. F).
KU 79467 (SK*. M).

7y<'mu/W/-;«',!,'(».— BeagleChannel: AM 443720
(SN, F). AM 44372 1 (SN. F), AM 4437 1 8 (SN, M ).
AM 443717 (SN. M). AM 443719 (SN. M). Cabo
Penas: BM 1929.6.14.3 (SN, F),SD 37.540 (SN. F).
Rio Grande: SD 38645 (SK. M). YA 1 1772 (SN. F).
YA11773(SN.F).BM 1932.7.12.1 1 (SN. M. J): RO
( 1 imcataloged fro/en adult male. lo be anatomical
specimen. I'rom lake 1 14 km south ol Ri'o Grande i.
Ushuaia: AM 44.3729 (SN. M). AM 443727 (SN.1-).
AM 443728 (SN. F). MA 5780 (SN. M ). MA 10006
(SN. M). KU 779.59 (SK. M). SW 3.'>41/KU 77960
(SN/SK. M), SW 3.542/KU 77961 (SN/SK, F), KU
77962 (SK, F), KU 77963 (SK, M), KU 77972 (SK,
Ml. KU 77973 (SK. Fi KU 79183 (SK, M), KU

79190 (SK. I-), KU 79191 (SK, l-|, KU 79192 (SK,
F) KU 79198 (SK, F), KU 79199 (SK. M). KU
79200 (SK. F). KU 79201 {SK. Ml. KU 79203 (SK.
M), KU 79204 (SK. F). KU 79205 (SK. Ml, KU
79207 (SK. F). KU 79208 (SK. M). YA82322 (SN),
YA 82323 (SNi, YA 82324 (SN), YA 82325 (SN),
YA 82330 (SN, F). YA 82331 (SN. F). YA 82332
(SN, M), YA 82333 (SN, F). YA 6485 (SK. M). YA
6845 ( SK,M),YA 8246 (SK,F|, MI 1572()(SK.F).
Viamonle: BM 1932.7.12.13 (SN. M, jl. BM
1928.4.21.1 (SN. Ml. BM 1928.7.21.2 (SN. Fi.
BM 1932.7.12.12 (SN. Ml. Isla de los Estados
(Staten Island): NM 49 101 3 (SK*.M).NM49 1014
(SK*.F).NM511771 (A). NM 51 1772 ( A. F). NM
536349 ( SN. F). NM 536350 ( SN. M ). NM 53635 1
(SN/SK, F).

Chile

Rc-.^ioii .v.— Corral: BM 96.12.31.7 (SN. F).
Valdivia: MA 4883a (SN. F). Chiloe and Baliia de
Ancud: AM 443741 (SN. M). AM 443743 (SN. M).
AM 44.^744 (SN. M). AM 443749 (SN. F). AM
443766 (SN. F). AM 443755 (SN. F). AM 443753
(SN. F). AM 443754 (SN. F). AM 443759 (SN. F).
AM 443762 (SN. F). AM 443763 (SN. F). AM
443740 (SN. M). AM 443742 (SN. M). AM 443745
(SN. M). AM 443746 (SN. M). AM 443447 (SN.
M ). AM 443748 (SN.M). AM 44375 1 (SN. F).AM
443756 (SN. F). AM 443757 (SN. F). AM 443758
(SN. F). AM 443760 (SN. F). AM 443761 (SN, F).
AM 44.3764 (SN, F). AM 443765 (SN. M), RO
3.5404 (SN, |F1), PH 81097 (SN, M), FD ••3888"
(SN, M). Codihue: KU 79840 (SK*. M). KU 79844
(SK*.M).RnsenadalIuito:KU79852(SK*.F).KU
79853 (SK*. F). KU 79854 (SK*. M). Lago
Llanquihue: KU 79849 (SK*. M). Lago Rupanco:
KU 79855 (SK*. F). KU 79856 (SK*. M). KU
79857 (SK*. Ml. KU 79858 (SK*. I-|. KU 798.59
(SK*. M).

R('i;ii>ii XI. — Puerio .\isen (mlerseetion ol Rio
Simpson and Ri'o Maihuales): FD "■24()7" (SN. M).

Rc:.iio/i XII.— Rio Ciaike: FD 104109 (SK. M).
FD 14774 (SN.F).FD 120519 (SN. F): FD 120521
(SN. Fd). I-D 120522 (SN.d). San Agostini Sound:
CM 120774 (SN. F). CM 120776 (SN. M). CM
120777 (SN. F). CM 120778 (SN. d). CM 120779
(SN.ill. Pucrlo Chnrucha: H.\l SO. 1 1 . 1 S.565 (SN.

STEAMER-DIICKS (ANATIDAE: TACHYIiKES)

103

F). E:ii/alx-th Island: BM 74.9.3. 2S (,SN. F). Puerto
Bucno: BM 79.9. .^.29 (SN. F). Bcrlrand Island: PH
SI 10.^ (SN. Fl. Wollaston Island: AM 4AMM (SN.
F). Navarino Island: .AM 44."W;i8 (SN. M). Straits of
Magellan: BM 80.1 1.18.. S65 (SN. F).

Falkland Islands

Easif-'alkUiiuls.— Cape Dolphin: BM 1940. 1 2.6-
36 (SN. |F|). BM 1940.12.6-36 (SN. M). BM
1940.12.6-34 (SN. F). BM 1940.12.6-35 (SN. F).
BM ••86" (SN. d). Bleakei- Island: AM 443785 (SN.
M). AM 443729 (SN, M). Fitzroy (Swan Pond): IS
I434(SN. M.d). IS 1451 (SN.M.d). IS 1452 (SN.
F. d). IS 1453 (SN. F. d). IS 1474 (Sn. F). Unspeci-
fied: BM 19.W.12.18.1 (SN, d). BM 1962.1.160
(SK. |F|).

UnspcdficJ.— BM 1928.7.21.18 (SN. d).

Taciiyeres brachyitervs (69)

Falkland Islands

East Falklaiuls.— Port Stanley: AM 443791
(SN,F).AM 443782 (SN, M), AM 443785 (SN,M),
AM 443788 (SN, M), AM 443784 (SN, M), AM
443786 (SN.M), AM 443783 (SN,M). AM 445783
( SM,M). AM 443789 (SN.Fl. Diamond Cove: BM
1932.7.2.41 (SN.d).Fitzroy:IS 1435 (SN. M.d). IS
1439(SN,M,d), IS 1454(SN,M,d). Lively Island:
KU 805 1 3 (SK*. F). KU 805 14 (SK*. F), KU 805 1 5
(SK*.M),KU80516(SK*,F).KU80517(SK*.M).
KU 80518 (SK*. F). KU 80519 (SK*. M). KU
80520 (SK*, M), KU 80521 (SK*, F), KU 80522
(SK*, F), KU 80523 (SK*, M), KU 80524 (SK*, F),
KU 80525 (SK*. M). KU 80526 (SK*. M), KU
80527 (SK*, M), KU 80528 (SK*, F), KU 80529
(SK*. F). KU 805.^0 (SK*. M), KU 80531 (SK*, F).
KU 80532 (SK*, F). KU 80604 (SK. M ). KLI 80605
(SK. M ). Sea Lion Island: AM 44377 1 ( SN. M ). San
Salvador: BM 44.1.18.66 iSN). San Carlos: HA
2204 (SK. F). Mare Harbour (Easi|?| Falklands):
BM 1 920.2.74 (SN).Unspecitied: AM 443773 (SN,
M). AM 443775 (SN.F).

West t'alkUinds.— Pebble Island: BM
1940. 1 2.6.33 (SN. F). New Island: Ml 1 .Vi206 (SK.
M). Mi 135895 (SN. M). MI 135897 (SN. M). MI
13589(1 (SN. F). Unspecitied: HA 2206 (SK. M).

Uuspccifu-d— BM 1940.12.7.26 (SN. M). BM
1940.12.7.27 (SN). BM 1949.52.38 (SK. M). BM
19,^.0.12.18.1 (SN). BM 1900.11. .30. 1 (SN.d). BM
1900.11.30.2 (SN. d). BM 1900.11.30.3 (SN. d),
BM 1900. 11.. 30.4 (SN.d).BM-725"(SN,M,j).PH
55809 (SN, M), PH 558 ID (SN, F), AM 419160
(SN), HA 70521 (SN), HA 70522 (SN); RS
1913.237.82 (SN). RS 1921.143.122 (SN). RS
1921.143.123 (SN). RS 1958.71 (SNs. 5 speci-
mens).

Tachyeres pteneres (132)

ARdLNTINA

licrid del Ftic;^o. — Beagle Channel: BM
1929.(-,|4.2 (SN, F), AM 443707 (SN. M). Gable
Island: AM 4437 14 (SN, F, j). Ushuaia: AM 4437 1 1
(SN. M). AM 443713 (SN, F), KU 77964 (SN, F),
SW 3543/KU 77965 (SN/SK, M), KU 77966 (SN/
SK, M). KU 77967 (SK, F), KU 77968 (SK*. F). KU
77969 (SK*. M), KU 77970 (SK*, M), KU 77971
(SK*, M), KU 79178 (SK*. M). KU 79179 (SK*.
M),KU79180(SK*,M),KU 79181 (SK*,M),KU
79182 (SK*, M), KU 79194 (SK*. F). KU 79195
(SK*. M). KU 790206 (SK*. F). Ml 157721 (SK,
M), SD 40490 (SK, F), YA 6486 (SK, M), YA 6487
(SK, M ), YA 82235 (SN, M ), YA 82236 (SN, F), YA
82237 (SN, M), YA 82238 (SN, F), YA 82240 (SN,
F,d),YA8224l (SN, F, d), YA 82243 (SN. F,d), YA
82244 (SN, F. d), YA 82245 (SN, M, d), YA 82335
(SN,F),YA 82336 (SN,F).BahiaBuenSuceso:NM
5.36348 (SN, M). Lapataia: SD 38646 (SK. M).
Harberton: BM 1932.12.14 (SN. M). BM
1932.12.20.1 (SN.d). lsladelosEstados:MA4144a
(SN, M), NM 490930 (SK, M), NM 490937 (SK),
NM 490939 (SK, M). NM 490942 (SK. F). NM
490943 (SK. F), NM 51 1767 (A), NM 51 1768 (A.
F), NM 511769 (A, F), NM 5411770 (A). NM
536349 (SN,F),

Cnii I

Rc:^ii>ii X. — Chiloe antl Bahia ile Ancud: AM
424579(SN.M).AM 35 I2()()(SN, M),AM 424578
(SN, M ), AM 424580 (SN, F), AM 44366 1 ( SN, M ),
AM 443663 (SN, F). AM 44.3664 (SN, F), AM
443665 (SN. F), AM 443667 (SN, M), AM 443668
(SN, M), AM 443669 (SN, M). AM 443671 (SN.

104

UNIV. KANSAS MIJS. NAT. HIST. MONOGRAPH NO. S

M ). AM 44367.^ (SN, M). AM 443674 (SN. F), AM
443675 (SN, F). AM 443676 (SN. F). NM 443677
(SN. F). AM 44.Vi78 (SN. F). AM 443680 (SN. F).
AM 4437 1 .5 (SN. F). PI I S 1099 (SN. M). LA 24902
(SN. F. d). I-D •■2399" (SN. F). FD "2400" (SN. F).
FD •■2401" (SN.M).FD "2402" (SN.F).FD 62419
(SN. M.d). KU 79S3.5 (SK*.F). EnscnadaC\Kliluie:
KU 79839 (SK*. F). KLl 70842 (SK*. M). KLI
79843 (SK*. F). Islas (iuailecas; CM 123.S55 (SN.
F.d).CMI23556(SN.M.d).FD"2763"(SN,M,d).

/?f'.?/VwX/.— Puerto Aisen: PH 16978 (SN. |F1).
Punta I.agunas: CM 120850 (SN. F).

Region Ml — Muiliroso Bay: CM 123470 (SN.
M.d). Almiranlc Bay: CM 123461 (SN. M.d). Isia
Hemiite: FD ••4695" (SN. M. j ). FD ••4696" (SN. M.
j). MA 42241 (SN, M). Isia Carolina: AM 443716
(SN.M).FalsoCabode Homos: AM446796(SN.M).
Cabode 1 lornos: AM 443683 ( SN. M ). Bahia Orange:
AM 733420(SN. M ). Isia London: AM 443694 (SN.
M). PH 81095 (SN. F. d). 3 unnumbered downy
young at AM . isia Wollasttin: AM 443686 (SN. M ).
Isia Navaruio: NM 488291 (SK). PH 81102 (SN.
|F|). San Agostini Sound: CM 120775 (SN. M).
BahiaEden:BM 1903. 12.30.199(SN.F).PH 120816
(SN).PH 120816(SN.M).PuertoBueno:PH 120795
(SN, M). Bahi'a Wide: PH 120813 (SN. M). Isia
Newton: SD 375.^) (SN. M ). SD 37582 (SK. F). Isla
Harbour: NM 18484 (SK. j). Caleta Lalitud: NM
18553 (SK. j). Bahia Tom: BM 80.1 1.18.563 (SN.
F).BM8().1 1.18.561 (SN.d). BM 80.8.3.25 (SN. M.
d). Straits of Magellan: BM 80. 11.1 8.564 ( SN. M ).
BM 42.7.36 (SN. |F1), RO 35406 (SN. | F| ). Walney
Sound: BM79.9.3..W(SN,M).C.rays Harbor. Smythe
Channel: BM 1903,12.30.200 (SN. M). Canal
Messier: BM 80. 1 i . 1 8.562 (SN, F), Bahia Churruca:
BM 1903.12.30.202 (SN. F). ••Magallanes I.": YA
22796 (SN.M.j). Unnumbered downy young at .AM
from IsIaTimbales. Isla Breeknoek (2), Isia Stewart,
and '•BeaL'le Channel."

Unsin-cifit'J — 'NM 18484(SK),NM I8553(SK),
AM 1222 (SK,F).

TaCHYERES LElCOCEI'inUS (61 1

Argentina

Chiihin— Bahia Concepeion: SD 38277 (SN,
M ). SD 38352 (SK. F). PuntaTombo: AM S5 1 3 (SK.
M). Puma Tafor: RO 146919 (SK. |M|). Bahia de
Huevos (Egg Harbour): AM 73.^415 (SN. M).
Camarones: MA 52194 (SN, M), MA 52195 (SN.
M). MA (uneataloged, Kovaes No. 75) (SN, M),
MA (uneataloged, Kovaes No. 76) (SN, F), YA
82328 (SN. F). YA 823.^4 (SN. M. d): RO— 2
uneataloged. frozen birds (M. F) to be preserved as
anatomieal speeimens. Puerto Melo: MA 52694/
KU 77932 (SN/SK. M. holotype). MA 52698 (SN.
M. d); MA — 3 unaeeessioned skeletons given by P.
S. Humphrey in 1984; KU 77925 (SK*. M). SW
3527/KU 77926 (SN/SK. F). KU 77927 (SK*. F),
KU 77928 (SK*.M). KLI 77929 (SK*,F),SW 3528/
KU 77930 (SN/SK. M). KU 77931 (SK*. M). KU
77933 (SK*. M). SW 353()/KU 77934 (SN/SK, F),
KU 77935 (SK*. M). SW 353 1/KU 77936 (SN/SK,
F), KU 77937 (SK*. F). KU 77938 (SK*. M). KU
779,HJ (SK*. F), KU 77941 (SK*. F). SW 353.VKU
77942 (SN/SK. M). SW 3534/KU 77943 (SN/SK,
M ), KU 79234 (SK*, M). KU 79235 (SK*. M). KU
792.^6 (SK*. M). KU 79237 (SK*. M). KU 79238
(SK*. F). KU 792.^9 (SK*, F). KU 79240 (SK*. F).
KU 79241 (SK*. F). KU 79243 (SK*. M. j). KU
79244 (SK*. M). KU 79245 (SK. M). KU 79246
( SK*. M). KU 79247 (SK*, F), KU 79248 (SK*. M ).
KU 79249 (SK*. F), KU 79455 (SN/SK, F), KU
794.56 ( SN/SK, M), KU 79624 (A.d). KU 79625 (A.
d). KU 79626 (A. d). KU 79.501 (SN. F, d), KU
79502 (SN, M, d), KU 79457 (SK*, F), MA 53329
(SN,F). MA 533.^0 (SN.M).

STEAMER-DUCKS (ANATIOAE; TACHYERES)

LH KRATl RK CH KD

105

Sources containing references to steumer-iiucks
are indexed by subject using combinations of one or
more single-letter designations; these follow the
references and are enclosed in square brackets. The
12 desiiinalions and their meanings are as follows:

A

anatomy

B

behavior

C

captive birds

D

distributional data

E

exploitation by humans

F

leeding habits

H

habitat

L

locomotion

M

minimal mention

N

nesting

P

predation

T

taxononn

ABBorr. C. C. 1S6I. Notes on the birds ol the Falkland

Islands. Ibis .^:149-167. [A, E. N. T|
Ad.\.ms.W.,.^ndR.Templetii\. I 'JTy. Ornithology. Pp.,^2-

53 m Cambridge expedition toTierra del Fuego ]'-)n.

A general report and summary of seientifie results.

Cambridge, England. |D. R H. N]
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Brockhaus. Leipzig. [D. H. L|
AoosriNi. A. M. di;. 195.s. Trent' anni nella Terra del

Fuoco. Soe. Edit. Intemat.. Torino. |L|
AvoN'iMot's. I91S. Canje y correspondeneia: hue\os \

aves do las islas Malvinas. Homero 1:205. |N|
Anonvmois. 1920. Bibliografi'a: recientes piiblieaeioiies

omitologieas sobre Sud America y espeeialmeiue ki

Argentina ypaisesveeinos, 1915-1916. Hornero2:75-

80. lA.Tj
Ano.nvmoi's. 1933. Huevos de aves dc Ticrra del Fuego.

Homero 5:228-230. IT]
Anonymoi s. 1935. Aves ingresadas al miiseo. Homero

6:123-125. |N|
Anonymoi s. 1943. .'\ddeiula a la "Lisia sisiemalica de las

aves Argenlinas." Homero 8:309-312. |D,T|
Anonymoi s. 1950. Waterfowl collection. Wildfowl 3:42-

45. |C|
Anon'i \uii s. 1951. Waterfowl collection. Wildfowl 3:33-

54. |C|
Anon'i Moi s. 1^52. .Atldilions to the collection. Wildlnwl

5:49-51. |C1
ANl)^^vI(ll s. 1957. Slimbridge UM7-57. Wildlow 1 9: 15-

20. |C|

.^Nl)N^\|()l s. 195S.Obtainiiigiiew birds. Wildlow I 10:12-
15. |C1

Anonvmoi s. 1967. Birds 27 — Mammals I I. .America's
First Zoo 14:20-21. |C|

Anon'imois. I'->73. Slimbridge: breeding results 1972.
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Anonymois. 1974. Breeding results. 1973, Wikhowl
25:171-173. |C|

Anon>\iois. 1978. Research, conservation and educa-
tion. Wildfowl 29:16.3-176. |C|

Anon'imois. 1982. Wildfov\l Trust avicullural report.

1981. Wildfowl 33:174-175. [C|

Anon'i MOtLS. 1983. Wildfowl Trust avicullural report,

1982. Wildfowl 34:174-175. |C|

Anonymoi s. 1984. Wildlow I Trust avicullural report,

1983. Wildfowl 35:182-183. |C|

Anon'imois. 1985. Wildfowl Trust avicullural report,

1984. Wildfowl 36:154-155. |C|

Anon'imois. 1986. Wildfowl Trust avicullural report,

14S5. Wildfowl 37:178-179. |C|
Anon'imois. 1987. Wildfowl Trusi avicullural report,

1986. Wildfowl 38:156-157, |C|

Anonymolis. 1988. Wildfowl Trust avieullurai report,

1987. Wildfowl 3'-): 180-181. |C|

Ak Vi \, B. l"-)82. Lisla patron de las aves chilenas, Publ.

Ocas. Inst. Oceanol. Liniv. Valparaiso No. 1:1-19.

ID]
Akvi a M., B.. G. Millie H., .and M. Beknal M. 1 986. Gui'a

de cainpo de las aves de Chile. Edit. Univ., Santiago.

I A. D. H. L. T]
Ai STIN.O. L.,Jr. 1961. Birds ollhe world. Golden Press.

New York. |M]
BxiDwiN, S. p., H. C. Obekholser, and L. G. Worley.

193 1 . Measurements of birds. Cleveland Mus. Natur.

Hisi. Sci. Publ. 2:1-143.
B \RRos v.. A. 1971. Aves observadas en las islas Pieton,

Nueva. Lennox y Navarino Oriental. Anal. Inst.

Patagonia (Punta Arenas. Chile) 2:166-180. |B, D|
Bakros v., R. 1945. Notas sobre niditicacion de aves

chilenas. Rev. Universitaria .30:181-202. |D. N]
BarrosV.,R. l948.Anotaeionessobrelasa\esilcMaulhn.

Rev. Universitaria 33:3.^-60. |D|
B \i \ii I . J. J.,.A. S. Kino, A. M. Li cas, J. E. Bre,\/ile, and

H, E. Ev \ns, eds. 1979. Nomina anatomica avium.

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Beck, R. M. 1918. Narrative of a bird quest in the vicinity

ofCape Horn. Amer. Mus. J. New York 1 8: 1 -1 6. 1 1 1-

119. ID.Nl
Bi iiiivrii. F. E. 1897. Nole upon intercenlia m llie verte-
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465-472. |A|

106

UNIV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. 8

Bl nDM<D, F. E. 1S9S. The strucUirc ;md ckissiticalion ol

birds. Longmans. Green, and Co.. London. |A|
BttR. J. V. 1%2. The rapid sexing ol' downy Anatidae liy

Iheslruelinv of Ihe syrinx. Wikirov\l 14:160-162. |A|
BrHN. F. 1942. Nonibres vulgares de aves silvestres

chilenas. Bol. .Soc. Biol. Concepcion 16:117-122. |D.

L.Tj
Bi;nnett..-\.G. 1924. Nolassobreel pato vapor /(/i/noc.v

pulMhimutis (King) llamado "Canvas-back" en las

Falklands. Hornero 3:280-282. |A. N, T|
Bi-,NNETT. A. G. 1926. A list of the birds ol the Falkland

Islands and tiependencies. Ibis 68:306-.533. [L. N. T|
Bi:no, M. 1982. What steams, lights and doesn't tly?

Ducks Unlimited 46:.30-34. |H. L, T|
BuRLio/. J. 19.^0. Systematique. Pp. 8.-^4-1055 in P-P

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biologic. Tome \V, Oiseaiix. Massonel Cic. Edileiirs.

Paris^TI
Bf-RNath. E. L. 1 965. Observations in southern Chile ni the

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Berndt. R.. and W. Mr.isE. 1962. Naturgeschichte der

Vogel. Vol. 2, Spezielle Vogelkunde. Franckh'sche

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Bertoni.A. deW. 1913.Contribuci6n para unealalogode

aves argentinas. .^nal. Soc. Cien. Argentina 75. |M|
Bi.A,'\i.)W. F. E. 191 2a. .Across South America to Tierra del

Fuego and back through the Smith-Channel. Notes

Leyden Mus. 35: 1-75. (A. L. T|
Beaaliw. F. E. 1912b. Noordwestelijk Vuiuland en /i|n

Vogels. Ardea 1:2-11. |D.L1
Blaal w. F. E. 1916. Field-notes on some 111 tlic v\aterlovvl

olThe Argentine Republic. Chile, and Tierra del Fuego.

Ibis58:478^92. |A. F. L.T|
Blaauw. F. E. 1917. The steamer duck. Ibis 59:274-276.

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STEAMER-DUCKS (ANATIDAE: TACHYEKES)

appp:ndix

121

MlLTIVARIATK IdKNTIFK ATION OF

Spfximens

Bi\ AKi.ATF; Canonic \i Pi ois

Skin spcciiiiviis. A reasonably precise eiassili-
cation oIsUkIx skins to species can be achieved by
calciilaling llie scores of each on the lirst two
canonical variates shown in Fig. 25. These scores
are based on three of the four basic skin measure-
ments taken for most specimens in this study —
nail width, tarsus length (cranial surface), and
wing length (arc length of straightened wing, from
wrist). Scores on each a.xis are calculated by mul-
tiplying each measurement (mm) by the corre-
sponding coefficient in Table Al. then summing
the three resultant products with the 'constant"
term foi that axis. .Alter this is done for each axis,
the point can be plotted on Fig. 25 and its position
indicates its likely group membership.

Table Al. t'dctlicicnls (iion-siaiidardi/ed) and coii-
stanls lor lirsi Ivvo canonical variates torevlcrnal mea-
sureniciils (plotted in Fig. 15) separating the eight spe-
eies-so\ groups of Ten liycrcs.

Cocflicicnts lor Variate

Term

Nail width
Tarsus length
Wing length

CoiislanI

II

-0. S.S.I -0..^7.^

-0.207 -0.02(1

(I.()(i7 -0.074

.s.07(l

27.2.V^

Complete skeletons. An analogous method of
identihcaiion can be performed using the coeffi-
cients for the 19 skeletal measurements incorpo-
rated in the canonical axes depicted in Fig. 27. As
described for external measurements, scores lor a
specimen on each axis are calculated by summing
the "constant" term with the products of each

measurement (mm) with its corresponding coeffi-
cient; coefficients and constants forcane)nical axes
I and 1! for skeletons are given in Table A2.
Because of the greater precision and dimensional-
ity of the skeletal model, the resultant species-sex
classifications are significantly more reliable than
those based on external measurements.

Table .^2. Coefficients (non-standardi/ed) and con-
slanls lor lirst tv\o canonical variates for skeletal mea-
surements (plotted in Fig. 27) separating eight species-
sex groups of Ecu hvcies.

Coeflicients for Variate

Term

Humerus lenath

-0.294

-O.Ul

Ulna lenatli

0.752

0.247

LWM

-0. Ls,S

2.114

Femur head widlh

-(l.l)2.s

-0.03.5

Tibiotarsus length

-0.117

-0.015

Tarsometatarsus lensth

-0.049

0.009

LWM

-0.6,U

ll.()()5

Diuit-lll lenath

-O.O.sO

0.030

.Sternum keel leni;lh

0.0-Sl

-0.116

least width

-0.2I.S

-().27S

posterior width

-0.027

0.179

Coracoid length

-0.147

0.300

basal width

-0.194

0.521

Interacetabular width

-0.097

0.039

Interorbital width

-0.012

-0.1(14

Postorbital width

-0.024

-0.030

Aiitcirbital width

-0.011

-0.019

Hill height

-0.1 4.S

-0.124

length

-0.0.^9

-0.121

Constant

22. 2M)

-4.232

Cl-ASSIHC..\T10N Ft NCTIONS

General nwthodoloiiy. More powerful for
/'(//niv.vf discrimination among species-sex groups,
but much more tedious to u.se. are classification
functions. These functions are presented as coef-

122

UNIV. KANSAS MUS. NAT. HIST. M(JN(XiKAPH NO. 8

ticiciUs (U)r llic same variables iiicoiporalcd in ihc
associated canonical analyses) for £'(/(■/( i;;v'///7 con-
sidered in the analysis. Initially, one imist choose
the two groups to compare with respect to the
specimen at hand: this choice may be based on
information on sex, locality, plumage pattern, or a
preliminary plotting on the canonical axes de-
scribed above. The specimen is then compared
against the two groups simultaneously by calcu-
lating the score of the specimen using as coeffi-
cients the differences between corresponding co-
efficients for the two groups concerned. The re-
sultant score is then compared to those derived
using the mean measurements for the groups being
compared (Tables 3 anti 6); the group with the
score most similar to that of the specimen is the
group into which the specimen is tentatively clas-
sified. In theory, all such pairwise comparisons
can be performed, and the closest match indicates
the optimal classification for the specimen. For a
Tachyeres of unknown sex, this would require 28
pairwise comparisons for optimal discrimination
among the eight species-sex groups. In practice,
however, without the aid of a complete data set for
Tachyeres specimens and appropriate computer
support, most classifications will be based on dis-
crimination between a smaller subset of the groups
delimited by ancillary data associated with the
specimens to be identified.

Skin specimens. Coeflicients of classification
functions are given for skin specimens of un-
known sex in Table A3, and for skin specimens ol
known sex in Table A4. For example, assume one
wishes to classify a skin specimen ot a male
steamer-duck from coastal Chubut using classifi-
cation functions. Assume that the specniieii has a
nail wuhli of 14 mm. tarsus lenelh ol ()3 mm. anil

a wing length of 292 mm. Given that the specimen
is known to be a male, the coeflicients to use are
those for males only. (Table A4, in part.) Given the
locality, only two species need to be considered —
/ leucocephaliis and T. patachonicus. Therefore
the coefficients of interest are the differences be-
tween those given for these two species: i.e., the
coefficient for nail width is 7.4 1 S - 5.926 = 1 .492.
that for tarsus length is 4.239 - 3.485 = 0.754. that
for wing length is 1 .493 - 1 .76 1 = -0.268. and the
constant term is -395.204 - (-408.367) = 1 3. 163.
The score of the specimen is simply the sum of the
products of these coefficients with the correspond-
ing measurements; for this specimen the score is
( l.492)( I4)-K0.754 )(63)-f (-0.268 )(292)-i- 13.163
- 3.297. Performing similar calculations for the
corresponding mean values given in Table 6. the
"standard scores" are -5.494 for male T.
patcichonicus and 5.2 1 5 for male /'. leucocephulus.
By comparison of the signs of the scores, it is clear
that the specimen is to be classified as T.
Icucuceplialus.

Skelehil specimens. Coefficients of classifica-
tion functions for complete skeletons are presented
in Table A5 for the eight species-sex groups: be-
cause these functions achieve relatively high clas-
sification percentages, functions based on sepa-
rate sex analyses are not presented. Information on
locality oi simple ratios should be used to exclude
from consideration some of the species-sex classes
for the skeleton at hand. In addition, the syrinx is
preser\etl in many skeletal specimens of rar/ny'/cs.
and the jiresence of an asymmetrically inflated
bulla demonstrates unequivocally that the speci-
men is a male. Partial skeletons, those lacking
skidls and distal limb elements, can be classified
usine coefficients i:i\cn in Tabic A6.

STEAMER-DUCKS (ANATIDAE: TACHYFRES)

~ r^. >r.

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r I c> ri

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at)

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r^,

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— 73

^ z t- ^

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p U Z f- ^

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u

124

liNlV. KANSAS MUS. NAT. HIST. MONOGRAPH NO. S

O U-. O — O

c^ oc r-- sC ir-,

ri o\ ^c sc c;

i/~! o c: <~i (^1 ^ 3C

ri sO r*-, — ly-, — r^, O -^ ^ G^ — "f

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o ri ir^, 3^
r- r<, ir, ir-,

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ri sC •/"- C^ ^ >c X.

DC >r-. C; r- sC r- c;

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u_

rl^l^l:^c^^c — oco-t-
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— '^' r-^ n-i o ir-* oc ri — nC c:

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a-.

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rir-o^w-iO^— 'ri — oor^. — '

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f*-,

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ri

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ri

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r 1

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r- DC

't "t >^. r- C^ ri -T

-t o o ^ 1^ — -r

^ O oc IT", r I r 1 1/-,

X r^. O
-t X O

— ''i-rir'-, — -"to^riri-T — ur, ri

-r C> 1-^, — ri

ri IT-, r- — G^

-r -t c. c^_ i^.

ri r- d ■^' sC

r-ori(A-, o^nor^ri

r] 00 rr, c: ri rr, ir. o v*

w~, — O r I «r-. O ir, — -T

d d (-^l d -+ — — —' ^

O^ \C rr-, [^ .Q^ -f -f- yZ rr-,

ir. -T ri r-- — r- o^ r^. —

— ■ O ^ li^; — O O X cr

d — r-^ d ri oc — ri o

— ^ -t

— r- nC
q ^ o ^c

— d u-^i «i-]

r~- ri 1^

-t — C-

nC X C'

ri ^ r«-,

X X o

^c — _:

-tw^. O^-rrisC'-^. — X

O '^ ^ '■''- — >r-, O 3^ ir^,

w-i r-^ ir, V; 1^1 X ^c -f "f

d ri o^' d — ^d d tr] \C

c

3:

o o > -

— T a

li H P

Q Cr:

"2 -c " — ^ S

t i'l I '^ I ■;

■2 — is -£ "S -= — -

U £ £ S. < E

u

STEAMER-DUCKS (ANATIDAE: TACHYF.RES)

125

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ri sc r- w r~- ri ri ri 3C —

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IllillllilUnlll.lll .11 Jl

3 2044 072 228 786

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