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SMITHSONIAN
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MUSEUM
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UNITED STATES NATIONAL MUSEUM BULLETIN 265

The Evolutionary History
of the

Avian Genus Chrysococcyx

HERBERT FRIEDMANN

Director, Los Angeles County Museum of Natural History

Research Associate, Smithsonian Institution

SMITHSONIAN INSTITUTION PRESS

WASHINGTON, D.C.
1968

Publications of the United States National Museum

The scientific publications of the United States National Museum include two
series, Proceedings of the United States National Museum and United States National
Museum Bulletin.

In these series are published original articles and monographs dealing with the
collections and work of the Museum and setting forth newly acquired facts in
the fields of anthropology, biology, geology, history, and technology. Copies of
each publication are distributed to libraries and scientific organizations and to
specialists and others interested in the different subjects.

The Proceedings, begun in 1878, are intended for the publication, in separate
form, of shorter papers. These are gathered in volumes, octavo in size, with the
publication date of each paper recorded in the table of contents of the volume.

In the Bulletin series, the first of which was issued in 1875, appear longer, sepa-
rate publications consisting of monographs (occasionally in several parts) and
volumes in which are collected works on related subjects. Bulletins are either
octavo or quarto in size, depending on the needs of the presentation. Since 1902,
papers relating to the botanical collections of the Museum have been published
in the Bulletin series under the heading Contributions from the United States
National Herbarium.

This work forms number 265 of the Bulletin series.

FRANK A. TAYLOR
Director, United States National Museum

Contents

Page

PIO MEG CINETGS 258 Eh en age Be oy ee ee eh ee VII
SE TCRUL aLOND oe ae ayn ci Ste ee a eee SR ee 1
BeyAO MCHC IC TClAblONSNIDSE —... Ps os 2 Soo ee Ro oe ee 3
ReREE OTM CAM VAOT= tees = Sst ae el = te en a A ea pe 25
amrvsi ROC NA VIOR + 9. ohne eee see eile ee eee ee en es 34
Heatures’of brood parasitism in Chrysococcyx.--._...:2-..-..-..--...2 36
Eipsi selection and its!evolution= 224.2 5.452 -222462. 522156 4222 36
PORE DOCH GILG ee cattle se Shc ese RE Be Fei Slane 39

FEE ENO Tp) RST ee ees Shanes) ee te es es PP GN WES Ae nS ete aa ee 66
Mode ‘of ege-laying by adult cuckoos._.2_-—.-.--......-.-22..- == 81
VEOELCHO RICE DOSE OM = nie tart eh air ev eee eae 81
Intervalsbetweentegese ors sense see Vie ee a ae eee ee 85

Nema benOn CR esate 2 eis Sy les 2 ee Salve. Le lat 87
memoval of host.eggs by adult cuckoos:-<..-.22))- 222 oe eee 87
Elost-parasite nestling relations== 2.222230 252% eo ee 91
Eviction of nest-mates by nestling cuckoos__..__._..__._._.------_-_- 96
Pedgline feeding by adult cuckoos- 22222-2022 2.2 2-2 Se 98
PRIELE ys ATC CONCIUSIONG] 2 ce yoke oes Nie FA a Ve eee Se 103
PUR RGMESIO RA ern ett pot ig ah 5 9 DY ats oe Oe oe gt eres CNet ee 108
The existing species and their distribution____.___._.........-___.. 108
The plumages of Chrysococcyx flavigularis_._._....._.-.._._.._-------_--- 112

Pe ETT CGS eee eet. Se One, Se ENN oer cathe, De eee We A 113
NEVES sath a Se AE en et A i ae ek wn Ae Bl ee A Oe 129

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Acknowledgments

The present study is the second in a series which, when completed,
hopefully may provide the background for a better understanding of
the phenomenon of parasitic breeding in the Cuculidae. The first
paper in this series [Friedmann, 1964] dealt with the crested cuckoos,
forming the genus Clamator. The genus covered in the present paper
contains three times as many species as Clamator and occupies a
much wider portion of the land areas of the Old World. It is the first
attempt to study all the glossy cuckoos as a group. In the past the
African species have been dealt with by specialists on African birds,
the Australian and Malaysian ones separately by other regional
students, and the Asiatic ones by still other writers. Until a compre-
hensive and comparative study of all of the glossy cuckoos was made,
it was impossible to compare meaningfully the known facts about
the life histories of these birds.

As in the earlier study of Clamator, the attempted appraisal of
the phylogenetic relationships of the 12 species of Chrysococcyz
demanded careful examination of large amounts of preserved material
of each species. A research grant from the Frank M. Chapman Me-
morial Fund of the American Museum of Natural History enabled me
to spend 19 very productive days at the British Museum (Natural
History) in London and also to examine the extensive material in
the American Museum of Natural History. These two collections
comprise by far the bulk of the pertinent material. The specimens in
the United States National Museum in Washington were also studied.
To the custodians of these bird collections I express my thanks for
their cooperation in making these materials available to me.

Museum study specimens were examined to ascertain the nature,
the frequency, and the distribution within and between the dozen
members of the genus of the types of plumage patterns, plumage
phases, and kinds and degrees of variation within these patterns and
phases. This survey was made with an eye to any phylogenetic
suggestions that might be adduced from the many hundreds of
specimens studied.

By correspondence with the unfailingly cooperative curators of
their respective collections and, in a few instances, by loans of selected,
critical specimens, I have been able to make use of the data on per-
tinent material in the museums of Bulawayo, Durban, Nairobi, and

vir

vu U.S. NATIONAL MUSEUM BULLETIN 265

Pretoria, in Africa; of Bombay, Singapore, and Manila, in Asia; of
Sydney and Adelaide, in Australia; of Berlin, Copenhagen, Genoa,
Leiden, Milan, Paris, Stockholm, Turin, and Vienna, in Europe; and
of Ann Arbor, Cambridge, Chicago, and Los Angeles, in the United
States. To the officials of these museums who have helped me with
data or specimens in the past 25 years I offer my thanks. The following
individuals also have assisted with contributed field observations,
with egg-specimen data, and with other relevant information: S. A.
Ali, L. Auber, R. K. Brooke, A. C. Cameron, A. H. Chisholm, G.
Duve, T. Farkas, N. Favaloro, N. C. Fearnley, M. T. Goddard,
F. Haverschmidt, K. A. Hindwood, A. Hoogerwerf, L. Hyem, M. P.5.
Irwin, C. H. Jerome, F. Johnston, R. Kreuger, R. Liversidge, C. J.
Marinkelle, A. R. McGill, A. R. McEvey, W. Meise, H. M. Miles,
P. Millstein, B. V. Neuby-Varty, J. Ottow, J. Paludan, E. Pike,
C. R. S. Pitman, O. P. M. Prozesky, R. A. Reed, E. H. Sedgwick,
D. L. Serventy, C. J. Skead, R. H. N. Smithers, G. Symons, R. E.
Symons, V. G. L. van Someren, C. J. Vernon, J. G. Williams, and
J. M. Winterbottom. Mr. K. A. Hindwood kindly helped me with
the nomenclature of Australian birds and also put me in touch with
a number of the Australian contributors, whose names are listed
above. Others who assisted me in various ways in the past but who
will not see this publication are the late E. Ashby, E. C. S. Baker,
J. P. Chapin, and A. Roberts.

My personal field experience with Chrysococcyz, although limited
to three of the four species that occur in Africa, formed my original
basic interest in this group and played a contributing role in the
present study. This field experience was made possible by grants from
the National Research Council, the American Philosophical Society,
the John Simon Guggenheim Memorial Foundation, and the Smith-
sonian Institution.

Permission to reproduce a map (fig. 4) from Fundamentals of
Ornithology by van Tyne and Berger was granted by the publishers,
John Wiley & Sons.

The colored plates of the plumages of the glossy cuckoos were pre-
pared for this publication by Evelina R. Templeton, scientific illus-
trator of the Los Angeles County Museum of Natural History.

For her patience with endless changes in the manuscript and for her
careful typing of the final copy, my thanks are due my secretary,
Myrna L. Patrick.

The Evolutionary History
of the

Avian Genus Chrysococcyx

Introduction

The genus Chrysococcyz is one of a number of genera of cuckoos
that are brood parasites in their reproductive habits. Their phylog-
eny, differentiation, dispersal, and ethology—all of which are re-
viewed in a comparative, yet detailed, way for the first time in this
paper—are of interest in themselves not only as a special “‘case
history” in the development of parasitism, but also for the lght
they throw on the broad, general problems of evolution of parasitic
reproduction in the cuckoos as a family and in birds in general.

As I pointed out in an earlier paper on Clamator (1964) the various
genera of parasitic cuckoos reveal divergent paths of development in
their mode and degree of specialization as parasites. Chrysococcyz,
for example, agrees with Cuculus in the evicting habit in the early
nestling stage, a phenomenon not present in Clamator; it agrees with
both Cuculus and Clamator in the habit of host-egg removal by the
adult cuckoos from parasitized nests. Among its dozen included
species Chrysococcyx presents a broad range of host-parasite situa-
tions, from those found in species like malayanus and osculans with
only a very small number of regular hosts to those shown by others
like lucidus (plagosus), basalis, klaas, and caprius with many dozens
of host species apiece. Chrysococcyr agrees more (but not rigidly)
with Cuculus than with Clamator in the intensity of parasitism on
its usual hosts, as measured by the incidence of multiple to single
eggs in individual nests of the latter.

Among the most interesting and intriguing biological problems
exhibited by the glossy cuckoos are:

1. The atavistic retention of courtship feeding by the adult
male with the correlated fledglinglike behavior of the female; 2. the
still more atavistic (but not infrequent) fledgling, and even nestling,
feeding by adults of these parasitic breeders; 3. the tendency, def-
initely begun but far from perfected, toward primary differentiation
in host selection by sympatric species of the genus; 4. the achieve-

it

2 U.S. NATIONAL MUSEUM BULLETIN 265

ment of various degrees of similarity to host eggs by the eggs of
different species of glossy cuckoos, and the lack of continuity of
pattern found in the development of this favorable adaptation in the
phylogeny of the genus Chrysococcyzr; 5. the fact, related to the
preceding, that various glossy cuckoos show different degrees of
egg morphism or the lack of it (one phenotypic egg) ; 6. the enormous
diversity of migratory behavior in different segments of the genus
and even in regional, geographic portions of the total population of
some of the species; 7. a remarkable and, apparently, a fairly abrupt
change in the plumage patterns of the young; 8. a great intensifica-
tion of sexual dimorphism in the adult plumage in some species of
the genus and not in the others; 9. the fact that the genus shows a
multidirectional radiation of differentiation, not one main line of
progressive alteration from a presumably earlier, more ‘primitive’
to a later, more “advanced” stage.

As will be seen from the body of this paper, the glossy cuckoos
do not reveal any such striking reversal of evolutionary trends as
that found among the crested cuckoos. They do present a picture of
interest in that they form an ancient group with definite gaps in its
composition due to the fact that a number of evolutionary inter-
mediates between current species have long since disappeared without
a trace. The glossy cuckoos may be numbered among those cases that
are all too numerous in nature but that fail to be reported on in detail
since they do not lend themselves to as convincing and as readily
accepted reconstructions as do others where the steps between all
present species are more easily discerned.

My experience with Chrysococcyz in the field is limited to 3 of the
4 African species (the genus contains 12 species in all), and, as will be
shown in this report, these African members of the group probably
are phylogenetically the more recent species of the glossy cuckoo
assemblage. However, over many years, I have compiled, compared,
and studied data on all aspects of the life histories of all the included
species, including much unpublished material kindly sent me by
cooperative and generous observers. The scattering and haphazard
nature of many of these discrete bits of data, and the wide range of
accurate detail (or lack of it) in many of them has made it difficult
to correlate, appraise, and interpret them, and it has therefore become
imperative to undertake a careful synthesis and reconstruction of the
past history, vicissitudes, and relationships of the group as a whole.
Inasmuch as this reconstruction is basic to our evaluation of brood
parasitism in the glossy cuckoos, we may now turn to the composition
of the group and to their apparent natural arrangement.

The data and their discussion and interpretation are presented in
this paper in the following sequence, to give a coherent picture of

AVIAN GENUS CHRYSOCOCCYx S

the evolutionary history of the glossy cuckoos. The morphological
differentiation of the group as evidenced by the apparent phylogenetic
relationships of the existing forms is presented in detail. Following
this, the comparative data on migratory behavior are described to
help explain the present geographic distribution of some of the various
species of the group. The similarities and the differences in the court-
ship habits of the species are then considered for the glimpses of past
history they reveal. With this background as a basis we then discuss
each important behavioral segment of the parasitic habit in the
glossy cuckoos, with all the data pertinent to the problem of host
selection and its evolution; of host specificity; of egg morphism and
its importance as evolutionary material; of the mode of egg-laying by
the parasites; of removal of host eggs by the cuckoos; and of the highly
specialized relations between the nestlings of the hosts and of the
parasites. This is followed by a discussion of all that is known of the
eviction of nestmates by the nestling cuckoos and of fledgling feeding
by the adults. Both of these behavior patterns are highly significant
in the biological history of the glossy cuckoos.

All these data and all the ideas pertinent to them are then brought
together and summarized. An appendix provides in its first part a
distributional check list of all the members of the genus Chrysococcyx
and in its second shorter part, brings together the earlier and the
more recent knowledge of the plumages of one species, hitherto very
inadequately described.

Phylogenetic relationships

My Wy,
Yj Ui} Yy (f$
YO) ik
\ Y/ wo fe
Ys i}; YY yy,
if Ki Yj id IH 4 Wy
UY UI LLY YU SRL ;
YY iff 7 Yi / i, Y Yf Y; 7, a
YY Yj / Yf y (y
Yy fy Yi Yj
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Wi
TU //

Ficure 1. Geographic range of the genus Chrysococcyz. [Shaded area in the Austro-
Malaysian region should be taken to refer to land areas only.]

4 U.S. NATIONAL MUSEUM BULLETIN 265

The glossy cuckoos, with which one nonglossy species, osculans, is
here united, following Serventy and Whitell (1962, p. 268), form a
fairly homogeneous group of small, parasitic cuckoos inhabiting New
Zealand, Australia, the East Indies and the islands of the southwest
Pacific, southeastern Asia and India, north to the Himalayas, southern
Tibet, and Szechwan, and all of Africa south of the Sahara. Within
this enormous range the group is represented by 12 species, with a total
of some 32 currently recognized species and subspecies: Of these 12
species, 7 (basalis, caprius, flavigularis, maculatus, meyerri, osculans,
and ruficollis) are monotypic while 5 have more than a single form
each. Of these 5, 2 (xanthorhynchus and klaas) have 3 races each,
2 (cupreus and lucidus) have 4 apiece, while 1 (malayanus) has
no fewer than 11 subspecies, due no doubt to its occupation of many
oceanic islands with correspondingly greater opportunities for the
formation of isolated gene pools.

In much of the recent literature one of the Australian species,
osculans, has been placed in a monotypic genus Misocalius, chiefly
because it lacks the metallic gloss on the upperparts found in the rest
of the species; the four African species (flavigularis, klaas, cupreus,
and caprius) have been kept in Chrysococcyz, and the seven Indo-
Australian ones (basalis, lucidus, malayanus, maculatus, xanthorhyn-
chus, ruficollis, and meyerit), in Chalcites. These three genera are
actually one group, for which Chrysococcyz, as the oldest name avail-
able, must be used. That they were not merged long ago is probably
due to the fact that the included species were dealt with chiefly by
regional specialists who did not attempt to study them all together.

Many years ago Sharpe (1873, p. 579) admitted that, were it not
for their glossy plumage and small size, he could not separate generi-
cally these species from the larger, plain-colored, long-tailed birds
of the genus Cuculus. Similarly, the genus Cacomantis is difficult to
separate from either by trenchant characters. Yet each of the three
is a “natural” assemblage, and as such each commends itself to
generic status in the opinion of all taxonomists with extensive know]-
edge of, and experience with, these birds. Thus, the species osculans
which seems like a link between Cacomantis and the Indo-Australian
section of Ohrysococcyz, possessing the relatively long bill of the former
and the shorter, less graduated tail of the latter, agrees with the
latter in its unbarred and unstreaked juvenal-plumage pattern, and
therefore is better placed in Chrysococcyz.

Even Mathews (1918, p. 337), who kept osculans in a separate
genus, wrote that its evolution from an ancestral “form of Lampro-
coccyz is presumed, and if it spreads to the wetter districts it is sure
to become darker, more glossy and more like a Glossy Cuckoo than
the desert bird is. The egg suggests that of the Bronze Cuckoos,

AVIAN GENUS CHRYSOCOCCYX 5

while it is recorded that its flight recalls that of these latter birds.
.. .’ While not defending or criticizing Mathews’ assumed evolu-
tionary paths, I cite his statement as further evidence of the close
relationship of osculans with the glossy cuckoos.

The fact is the genera Cuculus, Cacomantis, and Chrysococcyz are
ancient, and, as so often happens in such categories, some have
differentiated in the direction of the others, making it very difficult
at this late date to distinguish between original similarities or differ-
ences and later convergences or divergences. This situation was
noticed by Mathews (1918, p. 384), who was a generic “splitter”
but who was moved to write that the gradation of the three groups
‘Ws very peculiar, as it is marked in most particulars, size, coloration,
length of tail, etc.; yet it is possible we see here again instances of
convergence, as often met with when dealing with ancient groups. .. .
The Bronze Cockoos have been continually separated from Caco-
mantis on account of their bronze coloration and smaller size; but
here again some species are dull, while it is obvious that the bronze
species are separable into groups and have evolved more or less
independently. . . .”’ Mathews then considered that the African
species, which he had looked at only casually, were quite distinct
from the Indo-Australian ones, and he assumed that they were
derived from a different source, a conclusion I consider improbable.
He did conclude that the Malaysian-Australian forms were a complex
assemblage and that the best guide to their affinities was to be de-
rived from their plumage changes. Unfortunately, he went on to
divide what is here considered one genus, Chrysococcyz, into no less
than five genera, Misocalius, Chalcococcyx, Lamprococcyx, Neochal-
cites, and Chrysococcyx. Had he studied the African forms more thor-
oughly, he might well have divided Chrysococcyx into two genera,
recognizing Lampromorpha as did many of the African specialists of
his time.

Peters (1940) apparently made no careful study of these cuckoos,
and he followed the then-current usage by recognizing Misocalius for
osculans, Chysococcyz for the African forms, and Chalcites for the Indo-
Australian species. Berger (1955), on the other hand, investigated the
anatomy (pterylosis, wing and leg myology, syrinx, liver, and intestinal
caecum) of a number of species of glossy cuckoos, fortunately in-
cluding representatives of three genera (as then recognized)—Chrys-
ococcyx (cupreus), Lampromorpha (klaas and caprius), and Chalcites
(lucidus), and he concluded that all were congeneric. He noted that
“anatomical similarities further suggest that cupreus and klaas are
more closely related to each other than to either caprius or lucidus.
Though lucidus possesses certain anatomical features exhibited by
caprius (especially the M. iliotibialis and the place of insertion of the

6 U.S. NATIONAL MUSEUM BULLETIN 265

syringeal muscles), in most respects lucidus is like cupreus. Therefore,
caprius is most unlike the other species of this genus.”

Of the 12 species of the group, the breeding habits of 9 are known,
and these are all parasitic. The three whose eggs and young have not
yet been discovered are ruficollis, meyerii, and flavigularis; it seems safe
to assume that these are parasitic as well. In other words, there is no
reason to think that any chronological stages in the development of
parasitism are to be seen in the members of this genus. Since Chrys-
ococcyx is obviously most closely related to other parasitic genera such
as Cuculus and Cacomantis, it is reasonable to conclude that the glossy
cuckoos were descended from Cuculinae that were already parasitic.
As we shall see, some special refinements of brood parasitism are to be
found in certain members of the group and not in others; refinements
such as egg similarity to host eggs, restriction of parasitism to a small
rather than a large number of host species, and atavistic behavior
patterns such as nestling and fledgling feeding. However, since until
now all the species of the genus were studied, not as an entity, but
almost solely according to geographic occurrence, it was impossible to
appraise the significance of differences in refinement, or atavism of
portions, of the behavior patterns associated with the annual repro-
ductive cycles of these birds.

The chief intention of my comparative survey of adequate series
of specimens of all of the 12 species was to enable me to suggest their
most probable phylogenetic pattern, according to which I might then
arrange and evaluate the data on various aspects of their biology.
The many hundreds of study specimens in the British Museum and
in the American Museum of Natural History were carefully examined
and compared, but even this ample material failed to suggest with
incontrovertible definiteness which particular pattern was the only
correct interpretation of the relationships and of the past history of
the group. It was impossible to conclude that the incomplete, cir-
cumstantial evidence of the present forms of the genus and of their
distribution pointed to only one interpretation. Too many—in fact
almost all—intermediate stages have long since disappeared in this
ancient assemblage. Even the “intuitive” grasp of a complex picture—
which actually is usually a result of time-requiring ‘mental digestion”
arrived at without any rigidly logical series of steps, and which results
in the generally clarified, or at least correlated, arrangement on which
taxonomists so often have come to rely and on which they lay such
store (often with sound reason)—has been less neatly precise in the
present instance than I could have wished it might be. This factor of
uncertainty is an almost universal characteristic of evolutionary or
phylogenetic reconstructions, and it is by no means peculiar to the
present one. I mention it only because so many times authors either

ee

AVIAN GENUS CHRYSOCOCCYX 7

leave it unsaid or minimize it in their effort to advance what seems to
them the best, if not the only, possible arrangement of their data.

Within the limitations expressed in this preamble, I will now
outline what seems to me to have been the past history, move-
ments, and differentiation of the glossy cuckoos. The group originated
in the Indo-Malaysian area, whence it spread to New Guinea, Aus-
tralia, New Zealand, to the islands of the southwestern Pacific, to
Burma, Assam, and India, and thence to Africa. The evidence will be
presented in the following pages.

First, I will mention the two major geographical dispersals the group
underwent, outlining the reasons for my interpretation. These two
great dispersals involved a westward-spreading movement from
southern Asia to Africa, and a southern- and southeastward-spreading
movement from Malaysia to Australia and New Zealand. The latter
was probably much earlier than the former in the history of these
cuckoos, but it is not possible to prove this since evolutionary rate of
change may have been more rapid in the westward-pushing African
stock than in the movement that spread to Australia and New Zea-
land. In other words, that the present African members of the genus
seem more distinct, more divergent from the ancestral stock may be
due to more rapid change in a new environment and may not neces-
sarily be an expression of greater age than that evidenced by the
lesser degree of morphological change exhibited by the present Aus-
tralian and New Zealand portion of the group.

That there are no glossy cuckoos in Madagascar and the other
islands of the central and western Indian Ocean (Comoros, Mauritius,
Reunion, Aldabra, the Seychelles, etc.) suggests that the westward
spread of this group from southern Asia occurred after the isolation
of Madagascar and the Mascarene Islands from Africa in Pliocene time.
The additional fact that two of the African species, caprius and
klaas, have been found in southern Arabia suggests that a more
northern route may have been taken. It is equally possible, however,
that these southern Arabian birds may be relatively recent émigrés
from Africa. Both are known from only a very few specimens—
caprius, indeed, from a single one, from Arabia—but klaas appears to
have bred there, according to Meinertzhagen (1954, p. 310).

Similarly, at the other end of the range of the genus, the fact that
the birds breeding in New Zealand (C. lucidus lucidus) and in southern
Australia and Tasmania (C. lucidus plagosus and C. basalis) migrate
incredible distances over the open oceans, sometimes as much as
2000 miles, to the Solomon Islands and to the islands of the Bismark
Archipelago, suggests a revealing annual retracing of their ancient
ancestral dispersal between their present southern and southeastern
breeding areas and their original locus of origin.

8 U.S. NATIONAL MUSEUM BULLETIN 265

The term “Jocus of origin’? must be accepted in a rather loose
sense, as we have no way of proving that the islands presently used
as wintering quarters were the original homes of these subsequently
migratory birds. It so happens that the main areas to which these
cuckoos now repair for their nonbreeding season, the Solomon Islands,
and, to a lesser extent, the Bismark Archipelago, have no resident or
breeding populations of glossy cuckoos. In the complete absence of
evidence as to what may have been the case in the remote past, it is
not possible to explain this geographical gap or even to ask if there
may once have been Chrysococcyx populations there. The current
absence of local birds may make these islands more readily “suitable”
for the New Zealand and Australian migrants, but even this suit-
ability is uncertain. In Africa the populations of the three species of
glossy cuckoos that breed in the southern portion of the continent
spend the southern winter in equatorial areas that contain resident
populations of all three. It may be that the absence of breeding fantail
warblers (Gerygone) in the Solomons is correlated with the lack of
resident glossy cuckoos, for both this favorite host and its parasite
occur on Rennell and Bellona Islands.

For the sake of greater coherence and clarity in this review of the
history of the differentiation and dispersal of Chrysococcyz, discussion
will be limited to species. The variations within each species will be
treated later as needed. At this point it is sufficient to say that in no
case do the infraspecific variations and differentiations throw any
doubts on the vicissitudes, here outlined, of the specific taxon of
which they are a part.

If we begin with the Indo-Malaysian area as the probable locus of
origin of the genus, C. malayanus would then seem to be the nearest
of the existing species to the original home area, as well as the one
most similar to the ancestral stock. As the most wide-ranging of the
Malaysian-Australian members of the genus, and as the most poly-
typic species of the entire group (with 11 races), it appears that
malayanus may well be the oldest of existing Chrysococcyx species.
It includes only tropical forms, most of which seem to be nonmigratory
as compared with the nearly related species lucidus and basalis,
parts of which are highly migratory. In their review of the subspecies
of malayanus, Hartert and Stresemann (1925, p. 160) noted that from
the Malay Peninsula eastward the races of this species inhabit almost
all the islands of the Malay archipelago, east to New Guinea and the
Fergusson Islands, and to the tropical portions of Australia. In his
discussion of the origin of the avifauna of Timor and Sumba, Mayr
(1944, pp. 172, 189) considered C. malayanus as one member of the
“Banda Sea” element, a group of species of more eastern origin that
supposedly came into these islands in Pliocene time. The species is

AVIAN GENUS CHRYSOCOCCYX 9g

not represented by breeding populations in the Bismark or the Solomon
Islands, where no glossy cuckoos are known to breed, and it is also
absent from Bali, Lombok, Sumbawa, Flores, and Sumba, as well as
from Palawan and the northern Philippines. The race minutillus of
northern Australia has been treated as a separate species by some
recent authors.

It requires no great imagination to see that lucidus and basalis are
closely related to the primordial ‘“‘malayanus”’ stock. The three species,
although quite readily distinguished, are sufficiently similar in appear-
ance to indicate that they are more nearly related to each other than
they are to any of the other species of the genus. As we have already
stated, malayanus has a very wide, discontinuous range involving
many islands. C. basalis breeds in southern Australia and Tasmania,
but winters northward in the Sunda Islands, from Java to Sumbawa,
and has been recorded as well from Borneo, Sumatra, the Malay
Peninsula, Celebes, the northern Natuna Islands, Kangean Island,
and Christmas Island (in the Indian Ocean). C. basalis is monotypic.
The third species, C. lucidus, has four races, being next to malayanus
in the degree to which it has broken up into geographically differen-
tiated populations. Its breeding range includes the same portions of
southern Australia and Tasmania (C. J. plagosus) as does that of
C. basalis; plus New Zealand and the Chatham Islands, and possibly
also Norfolk and Lord Howe Islands (C. l. lucidus); New Caledonia
the Loyalty Islands, New Hebrides, Santa Cruz and Banks Islands
(C. l. layardi); and Rennell and Bellona Islands (C. l. harterti). The
last two subspecies are resident; the first two migrate extensively,
plagosus wintering in the Lesser Sunda Islands, New Guinea, and the
Bismark Archipelago, and typical lucidus migrating through the
Louisiade Archipelago (Woodlark, Misima) to the Solomon Islands
and the Bismark Archipelago.

On the whole, C. lucidus seems closer to C. malayanus than does
C. basalis, and it may be significant that the eggs of the first two
species are fairly similar, uniform olive-bronze to olive-green, oc-
casionally with faint longitudinal streaks (as in C. m. poecilurus),
while those of C. basalis are very different, pinkish white, finely
speckled with pinkish red. C. basalis also has a bill relatively narrower
for its length than does either C. lucidus or C. malayanus, and it also
has more rufous in its rectrices than do the latter two species.

C. malayanus is slightly smaller than either basalis or lucidus and
is usually thought to differ from both in the pattern and extent of the
rufous coloration in the tail—all the rectrices in malayanus having
some rufous, while in lucidus the tail has little or no rufous on the
next to the outermost pair of feathers and in basalis there is no rufous
on the outermost pair of rectrices but a considerable amount of this

267-562—68

2

10 U.S. NATIONAL MUSEUM BULLETIN 265

color on the basal portion of the next three pairs. However, this
character of rufous coloration in the tail feathers varies considerably
within the species malayanus, and since lucidus (and its races) and
malayanus (and its numerous subspecies) do not overlap geographically
in the breeding season, it may not be too farfetched to ask if they may
not be conspecific, representative forms. Thus, within malayanus, all
the rectrices have rufous in the race inhabititing northern Queens-
land, C. m. russatus, while in C. m. minutillus there is no rufous in
the outermost pair of rectrices, although there is a considerable amount
of this color in the basal half of each of the next three pairs; in C. m.
rufomerus there is no rufous in any of the tail feathers; in C. m. malay-
anus there is no rufous in the outermost pair, although a considerable
amount in the basal portion of the next two pairs.

The species C. basalis not only has a narrower bill but also differs
in other proportions, such as the longer tail and somewhat longer legs.
It also is less bronzy colored above than malayanus or lucidus and its
throat is longitudinally striped or streaked, rather than barred as in
the latter two. It is more distinct from either malayanus or lucidus
than they are from each other. Also, that lucidus and basalis are
sympatric is further evidence of their specific distinctness; as said
above, however, this geographic argument does not apply to the
lucidus-malayanus picture.

At this point we come to a much more noticeable morphological
differentiation, a change that resulted eventuallyin thespeciesosculans.
Here the striking change is in the loss of the metallic, glossy coloration
in this bird, which is otherwise a larger relative of lucidus, basalis, and
malayanus. The eggs of malayanus are said (by North, 1912, p. 28) to
approach a chocolate-bronze color at times. It is possibly significant
that the eggs of C. osculans are a rich chocolate-brown color; this may
reflect some phylogenetic connection between the two, osculans being
a glossy cuckoo that has lost its glossy color but is otherwise an obvious
member of the group. However, egg coloration in parasitic cuckoos is
too selectively vulnerable and, hence, changeable in the course of
evolution to be, in itself, a very trustworthy index of relationship.
The most that may be said of osculans is that it is more probably
related to the other Australian congeners (lucidus, basalis, and malay-
anus) than to any of the other, geographically more distant species of
Chrysococcys.

We now come to two derivative species found in the mountains of
New Guinea, ruficollis and meyerit. The former is, essentially, fairly
similar to malayanus but has the throat and breast suffused with
rufescent. This poses no difficulty in a phylogenetic reconstruction
since malayanus (especially the subspecies C. m. russatus) shows a
trend in this direction. C. ruficollis, still a poorly known species, occurs

AVIAN GENUS CHRYSOCOCCYX tT

in the mountain forests at altitudes of from 2000 to 3300 meters, and
occasionally down to 1300 meters according to Mayr (1941, p. 73).
Fuller knowledge may reduce rujicollis to the status of a race of
malayanus, as was suggested by Rensch (1931, p. 544) who pointed
out that the two species do not overlap in their breeding ranges. Mayr
(1932) suggested that the tail pattern of rujicollis raised the possibility
of its close relationship to lucidus, and noted that the solution of this
problem must await fuller knowledge of the vocalisms, habits, and
eggs of these cuckoos.

The other species, C. meyerii, however, is, very distinct. Between
it and the stock of which malayanus seems to be the least changed
representative, there is a gap in the existing evidence. Not only is it
more brightly metallic on the upperparts, but the female has a wholly
new plumage character, with a bright-chestnut forehead and anterior
portion of the crown. This is the only species of the entire genus in
which this marked, brightly colored character has developed in the
female. The fact that the young of this species is unbanded below is
evidence that C. meyeri is related to the other Indo-Australian species.
It may be noted, at this point, that Iredale (1956, p. 185) has made
some comments about this species, which do not tally with the infor-
mation in his own book. He writes that the immature “‘is so unlike the
adult as to raise suspicion about all the distinctions cited in favour
of the separation of these Cuckoos by means of tail coloration. The
young bird, figured on Plate XII, Figure 9, shows no bronze above,
only a dullish green, while it is whitish below . . .,’”’ but the colored
figure he gives shows the entire upperparts of the bird from forehead
to tail pale chestnut-brown! C. meyerii is distinguished in both sexes
by a broad chestnut area in the remiges, by its brightly glossy-green
upperparts, and by its small size.

C. meyerii is a critical species in the evolutionary vicissitudes of
the genus. Not only is it the first expression of a trend toward bril-
liantly colored forms—a trend that again reveals itself in two species
of the Asiatic mainland, C. maculatus and C. zanthorhynchus—but it
is the first species (in this reconstructed phylogeny) that possesses
very distinct sexual plumage dimorphism. It is also the last species in
our present arrangement to possess the character of largely unmarked,
uniformly grayish or brownish ventral plumage in the young, agreeing
in this important respect with all the Australasian species and differing
from the two Asian and all the African ones, the young of which are
very strongly banded over the entire underparts. In some of the
Australian and Malaysian species the sides and flanks of the young
are banded, but these cross marks do not extend across the breast or
abdomen, and even in these species occasional completely unbanded
individuals occur (C. l. plagosus, Mayr, 1932).

12 U.S. NATIONAL MUSEUM BULLETIN 265

The change of this aspect of plumage patterns, associated as it
is with the presence of sexually dimorphic plumages in the adults, is
a biologically interesting development and merits further discussion
here. Ventral barring as a pronounced pattern is found in the young
of maculatus and «zanthorhynchus and of the four African species,
while the young of the Malaysian-Australian species have uniform,
unbanded underparts from chin to vent. Conversely, the adult males
of the latter group show a well-developed trend for crossbars on the
underparts, while all but one (flavigularis) of the former group do not.
In other words, a fairly basic pattern is associated with immaturity
in one group and with maturity in the other. The one western excep-
tion, CO. flavigularis, has the barred pattern on the abdomen in the
adult-female plumage, and in this respect it forms a significant link
between the two sections of the genus.

The biological appraisal of the evolutionary significance of ventral
barring is difficult to form. While such barring is characteristic of the
young of many other cuckoos of the subfamily Cuculinae, such as the
various species of Cuculus, Cacomatis, and Cercococcyz, it is absent
from others of such genera as Clamator, Scythrops, and Coccyzus.
It is, therefore, not necessarily an immature plumage pattern in itself,
although there are many birds unrelated to the cuckoos in which the
young are banded, spotted, or streaked, while the adults are relatively
free of such markings.

It should be kept in mind that we are discussing here, not an exact
replication of a transverse pattern, but a tendency to produce this type
of marking. In this connection, the following thoughts might well be
mentioned. If, as is widely assumed, the juvenal and immature
plumages tend to reflect earlier, more ‘‘primitive”’ phylogenetic stages
in the history of a group of species to a greater extent than do the
corresponding adult plumages, how are we to understand the reversal
of pattern sequence within such a fairly compact group as the glossy
cuckoos? One solution of this enigma would be to regard the Asiatic
and African species as a genus apart from the Malaysian-Australian
ones. This, however, would merely reword the question in terms of
two related genera instead of one somewhat divergent group of con-
generic species. Also, the plumage patterns of flavigularis, as already
mentioned, help to bridge the gap. If we were to interpret the presence
of strongly barred ventral-plumage pattern in the young as more
“ancient” than the absence of such a pattern, we might ask if the
Malaysian-Australian species were actually more recent in their
origin than the others. Yet this seems most unlikely; we can only
conclude that the tendency to produce a barred ventral-plumage
pattern in the young was developed at the time that a portion of the
ancestral stock began to spread westward to the Asiatic mainland and

AVIAN GENUS CHRYSOCOCCYX 13

that this tendency has been retained in all the species that have
arisen from that sezement.

On returning to our descriptive review of the genus, we come to a
gap between meyerii of New Guinea and the two Asiatic species,
maculatus and xzanthorhynchus. This is a gap both in existing birds
and in geography, and it should be made clear that the existing species
on the two sides of the gap are related but not necessarily immediately
derivative. Both are expressions, similar in some ways and distinct
in others, of a trend toward brighter, more glittering plumage. The
two species of the Asiatic mainland are closely related to each other,
although the adult males are strikingly different in appearance, that
of maculatus being bright metallic-green above and that of zanthor-
hynchus, bright violet. The females of the two are more alike, but
are readily distinguishable; that of maculatus has the crown and hind
neck between cinnamon and pale chestnut, and the upper parts of the
body light, but bright, green with a varying amount of coppery glints
and reflections; that of xanthorhynchus is bronze-green above, slightly
browner on the head and has all the upper wing coverts and many
of the dorsal body feathers banded with chestnut. Moreover, the
violet cuckoo is slightly smaller than the emerald one. The juvenal
plumages and the eggs of the two are very similar. The emerald cuckoo,
C. maculatus, is a monotypic species, known to breed in the Himalayas
from Kuman through Assam, southeastern Tibet and Szechwan, to
Hupeh, south to Yunnan, and Burma, migrating or wintering south
to India, Hainan, the Malay Peninsula, and Sumatra. The violet
cuckoo, C. xanthorhynchus, with three races (one of them of uncertain
status), occurs from Assam, southwestern Yunnan, and southern
Annam, south to eastern Bengal, the Malay Peninsula, Thailand, the
Andaman and Nicobar Islands, Sumatra, Lingga Archipelago, Java,
Borneo, and east to the Philippines (Luzon, Mindoro, Samar, Cebu,
Basilan, and [?] Palawan).

Alone among all the species of glossy cuckoos, the Asiatic emerald
cuckoo, C. maculatus, has been said to have two distinct seasonal,
adult-male plumages. Ticehurst (in Stanford and Ticehurst, 1939, pp.
15-16) was the first to call attention to this matter. He was aware
of the fact that in the earlier literature only one plumage was de-
scribed for the adult male, but he found that not only did the birds
undergo a complete postnuptial molt (as is normal for practically all
birds), but that in the new plumage the upperparts of the body were,
not bright green, but coppery-bronze and that the head, ear-coverts,
chin, throat, and upper breast became, not solid bright green, but
barred, similar in pattern to the rest of the underparts. He further
found that there was a less complete spring molt, whereby the solid
green of the breeding plumage was once more regained.

14 U.S. NATIONAL MUSEUM BULLETIN 265

If this species had two distinct, seasonal, adult plumages in the
male, this would constitute a real biological disparity, for no such
situation is known to exist elsewhere in the genus. Examination of
a good series of adult males (41 specimens) in the British Museum
partly, but not very convincingly, bears out Ticehurst’s findings.
It suggests that some of the adult males, presumably, but not cer-
tainly, birds in the first adult plumage, tend to be more coppery-
bronze and less bright green on the upperparts than do other (older?)
birds and that these same individuals tend to have the ventral bars
more bronze and less green as well. The appearance of a few white
bars on the throat and breast of adult males seems to be almost
haphazard (about 20 percent of the specimens showed one to three
such marks and these are not all examples taken in any one season).
Three examples, however, do show what Ticehurst described. Two
were collected at Dibrughur in August 1879 by J. R. Cripps, and one
at Bangkok, on January 25, 1923 by Sir W. J. F. Williamson. In
them the feathers of the forehead and the foreparts of crown, chin,
and throat are dark, bright green, conspicuously barred with white,
while the posterior parts of the crown, occiput, back, and rump show
a mixture of bright-green feathers with some that are darker and
more bluish, but hardly coppery bronze as Ticehurst wrote. This is
true for the two Dibrughur specimens, but not so for the one collected
at Bangkok. Inasmuch as this barred forehead, chin, and throat condi-
tion is shown by only 3 out of 41 fully adult males, it is not certain
that they really represent a distinct nonbreeding, adult-male plumage.
Since no such seasonal plumage is known for any of the other glossy
cuckoos, it would seem safer (but not necessarily more accurate) to
consider these birds as examples of partly retarded plumage char-
acters, retaining the bar-producing tendencies of the immature stage
beyond their usual duration. Deignan (1945, pp. 164-165) apparently
considered Ticehurst’s nonbreeding plumage stage uncertain, since he
referred to one of his specimens as ‘‘completing a molt from the
juvenal plumage to one like that described by Ticehurst . . . as the
dress of ‘the adult male in winter.’ ”’

Further evidence of the close relationship between zsanthorhynchus
and maculatus is afforded by four examples of males of the former in
early or later stages of molt from the immature to the adult dark-
purple plumage. In these four specimens, taken in the following
localities: two from Lower Pegu, December 20 and January 11,
1878; one from Bangkok, March 5, 1918; and one from Karen-nee,
March 15, 1874. The dark abdominal bars on these specimens are
bronze-green as in maculatus, although the new feathers of the throat
and upperparts are the deep purple normal to zanthorhynchus. Fur-

AVIAN GENUS CHRYSOCOCCYX 1

thermore, in the females of both species the ventral bars are very
similar, bronze-green in color.

It may be noted that in the majority of adult males many of the
bright-green feathers of the upperparts have vague subterminal dark,
but glossy, bluish areas which almost foreshadow the dark violet of
CO. xanthorhynchus. This is also especially the case with the inner and
terminal portions of the remiges, which are often dark purple. This
all suggests the not very surprising observation that the difference
between the violet xanthorhynchus and the dark green maculatus is
not as great as it might seem and that, in an evolutionary sense, it
is quite possible to accept a “leap” of such dimensions between two
related species. It may be mentioned, at this point, that considerable
purplish tinge occurs in adult females of ducidus (in the nominate
race, plagosus, layardi, and harterti). While these birds have a dull
purplish-bronze color, and not deep-violet as in zanthorhynchus, they
serve to indicate that the difference between purple and green is
less great than the visual appearance of the end result (as developed
in maculatus and zanthorhynchus) might suggest. Also, one cannot
help but recall somewhat similar suggestive, green-to-purple plum-
ages in some of the African starlings of the genera Lamprotornis and
Cinnyricinclus. Two male zanthorhynchus, in the American Museum
of Natural History, both marked “adult,” show the extremes of
coloration, the upperparts, throat, and breast being purplish-coppery
in one and deep violet-blue in the other,

At this point in our reconstruction of the past vicissitudes of
Chrysococcyr we come to the largest and most serious gap in the
available evidence, a gap that separates all the eight Indo-Malaysian-
Australian species from the four African ones (caprius, cupreus,
flavigularis, and klaas). So different are the latter group that it is
understandable that a superficial glance at them caused Mathews to
think they had little in common with their more eastern relatives
and to suggest they may have had a quite separate ancestry. How-
ever, this in not an acceptable interpretation, and closer study reveals
characters common to both groups. As already mentioned, the absence
of any glossy cuckoos from Madagascar and the other, smaller islands
of the central and western Indian Ocean suggests that the spread of
the group from southern Asia to Africa probably took place in Pliocene
or post-Pliocene time. It was, however, sufficiently long ago to have
permitted not only much differentiation from their eastern ancestral
stock but also to have provided the duration and opportunity for the
African glossy cuckoos to have formed two subgroups within them-
selves, one containing the didric cuckoo, C. caprius, and the other
comprising the remaining three.

16 U.S. NATIONAL MUSEUM BULLETIN 265

As is usual in phylogenetic reconstructions, there is no concrete
evidence by which to prove beyond question which of the four present
African species is nearest to the original stock that invaded that
continent. Careful comparison of all characters, habits, and dis-
tribution makes it probable that the invader is the klaas-flavigularis
section. These two closely related species are more like (or less unlike)
the Indo-Australian members of the genus than are either caprius
or cupreus, and of these two it seems that flavigularis is nearer to the
original émigré stock to Africa than is klaas. This is, admittedly, as
in all such evolutionary conclusions, a judgment rather than a proven
fact, and because of its nature as a considered opinion it is essential
that the evidence be given in detail at this point.

The yellow-throated cuckoo, C. flavigularis, is a monotypic, very
inadequately known, rarely observed, and seldom even collected bird
of the west African forest area. Because of its relative rarity in
collections, with a resulting paucity of observations on what may be
learned from the examination of specimens, C. flavigularis merits
discussion in some detail here. It is certainly the least known and
least adequately reported of the African members of the genus, and it
may well be less known than any of the Indo-Australian forms as well.
It is restricted to the forests of equatorial Africa, from Sierra Leone
in the west, to the Congo-Uganda border in the east, and south to
southern Cameroon and the forests of the lower Congo and of the
Kasai area. Although it is wholly restricted to the true forest and does
not venture out into the tree-dotted grasslands where its close relative
C. klaas is found, the latter invades the outer fringes of the denser
forest enough so that the two species are occasionally sympatric.
Curry-Lindahl (1960, pp. 111-112) found the two together in the
forest at Lwiro, in the eastern Congo. The fact of sympatry is evi-
dence of the fully established specific independence of the two, a
fact which had not been questioned by anyone in the meager lit-
erature of flavigularis, but which may be stressed here nonetheless.

In its character of barred underparts in the female and of barred
abdomen in the male, flavigularis seems somewhat intermediate be-
tween the other African glossy cuckoos, where this ventral barring is
purely a character of immaturity, and the Asiatic species, maculatus
and santhorhynchus. It cannot be proved, at this late date, whether
the stock presently represented by flavigularis was the original invader
of Africa from the Orient, or whether its ventral barring is merely a
reappearance or a perpetuation of a basic pattern in the old Chrysococ-
cyz stock, using that generic name in the broad sense. The species
flavigularis further agrees with the two mainland Asiatic species in
having the bill and feet yellow, not dusky as in its nearest African
relative, klaas. In as far as it may be possible to postulate an evolu-

AVIAN GENUS CHRYSOCOCCYX 7

tionary sequence from the circumstantial evidence of the contempo-
rary, surviving components of the genus, flavigularis may seem to be
closer to the original stock that came from Asia to Africa than is any
of its other African congeners. Actually, in its ventral barring flavigu-
laris has the pattern more narrowly and finely developed than any
of the Indo-Australian forms, and even suggests the finely barred
pattern of some species of Cacomantis (such as sonneratr). This point
is of suggestive interest, as one cannot wholly dispel the possibility
that Cacomantis, or some similar stock, may have been the remote
ancestor of the glossy cuckoos as a group.

That flavigularis is a bird of the West African forest belt is, if any-
thing, what one might expect of a descendant of an originally south
Asiatic stock, as most of the Asiatic “‘relicts’’ in Africa are found in
precisely that area. Admittedly, this is hardly a bit of evidence in
itself, but it is worth mentioning because, in a case where so little of
the past history of a group may be sensed convincingly from tangible
data, even a slight corroborative suggestion is welcome. Whether it
represents the primordial stock closely or not, favigularis has remained
a strictly sylvan entity like its Asiatic progenitor, and like maculatus
and zanthorhynchus it is difficult to see, to watch, and to collect.

We have already mentioned that C. klaas is quite obviously the
nearest relative to flavigularis, and the closeness of the two will be
shown even more in the following discussion of their plumage charac-
ters. Especially interesting evidence for this close relationship is
afforded by the fact that occasionally klaas may produce a female
plumage quite similar to that of flavigularis. This is certainly not
frequent or usual, but it does happen. It is illustrated by a female
klaas in the British Museum (B.M. 78-12-31-325), ea coll. R. B.
Sharpe, who got it from Layard from South Africa. It is fortunate
that this particular specimen came from an area where no question of
its being flavigularis could possibly arise, thereby eliminating any
question as to its correct identification. This revealing example differs
from other young or females of klaas in having the entire underparts
from chin to upper abdomen and sides pale buffy, narrowly barred
with dusky earth-brown, almost as in young or female flavigularis,
but with the wavy bars more widely spaced and with the middle of
the lower abdomen and the under-tail coverts whiter and less barred.
It has the wavy crossbars narrower than in any other of several hun-
dred examples of ‘laas examined. It is definitely a female klaas, al-
though it shows a surprising trend in the direction of female or juvenal
flavigularis in the pattern of the underparts. On the top of the head,
nape, upper back, and rump it is almost uniformly dull coppery-brown,
the seapulars and upper wing coverts bright green barred with cin-
-Mamon as in other females of klaas. Female flavigularis usually have

18 U.S. NATIONAL MUSEUM BULLETIN 265.

a bronzy wash over the copper-brown of the upperparts, and are
usually less brownish, more bronze than in klaas.

Another similarity between these two species is the bright green
gorget on the sides of the throat in adult males of the two. The fact
that the chin and middle of the throat in males of flamgularis is bright
yellow may be looked upon as a “step” that “ties it in” between
klaas and cwpreus, and it is of interest to find that in both flavigularis
and cupreus the yellow fades to white in post-mortem changes in old
specimens suggesting an identity in the chemical nature of the pigment
in the two.

Some notes on the actual plumage of flavigularis based on study
of specimens, and comments on what some other authors have written
about this species may now be given. Aside from the recorded differ-
ences between flamgularis and klaas in the plumages of females and
juvenals, and of the chin and throat color and that of the abdomen,
in the males, it may be said that the upper parts of males of flavigularis
have more coppery-bronze tones than do those of klaas. At this point,
it may be well to correct one detail in the description given by
Mackworth-Praed and Grant (1957, p. 512), who write that the under-
parts of the body of flavigularis are narrowly barred with dark green;
it would be more accurate to say it is marked with brown bands with
not more than a slightly greenish-bronzy wash.

The tail pattern in flavigularis is unique; the two median rectrices
are uniform purplish-coppery color, the next pair dark brown glossed
with coppery and with white tips and broad, white outer margins to
the basal three-quarters of their outer webs; the remaining three
pairs are pure white with a subterminal bar of blackish-bronze, the
bars becoming narrower centrifugally. In klaas, on the other hand,
there is no white on the four median rectrices, and the three outer
pairs are white with five or six narrow, incomplete dark bars.

Shelley’s colored plate (1879, p. 679) accompanying the original
description of jlavigularis shows the bird as having superciliary
streaks and the ear-coverts a bright purplish-copper color; these
characters are certainly not present in the adult males I have ex-

amined. An adult male from River Ja, Cameroon, in the British —

Museum (B.M. 1911-5-31-119) has the entire top and sides of the

head, upper back, lower back, and upper wing coverts a dark bronze- —
green, quite devoid of any “fiery copper” or “lilac bronze” mentioned _
by Shelley. Bannerman (1953, vol. 1, p. 583) also gives an inaccurate |
picture when he writes that flavigularis “has not the brilliance in the |
plumage of the other Golden Cuckoos, the upper side appearing in |
both sexes more of a purplish bronze . . . .’”’ It is darker green, less |

glittering but hardly purplish-bronze.

It seems correct, however, to agree with Shelley’s conclusion that j

AVIAN GENUS CHRYSOCOCCYX 19

the klaas is the closest living relative of favigularis, and it is reassuring
to find that specimens of the latter show this all the more by lacking
the excessive coppery or purplish hues described by Shelley when
he first made the species known.

In his study of the African glossy cuckoos other than flavigularis
(which apparently was not available to him at the time), van Someren
(1925, pp. 660-662) correctly concluded that klaas was more nearly
related to cupreus than to caprius. He listed 10 characters in proof
of his conclusions, and we may now review them with flavigularis
in mind.

1. There is little gold or bronze in the dorsal green color of klaas
and cupreus, while there is much of this in caprius. In this respect
flavigularis agrees with klaas but is even duller.

2. Both klaas and cupreus have a “frosted” appearance in their
dorsal feathers, while caprius has a smooth, silky appearance. In this
regard flavigularis has neither.

3. In the adult male klaas and cupreus have metallic green
feathers on the sides of the throat, and caprius does not. Here flavi-
gularis agrees with the first two.

4. The outer tail feathers of juvenal and female klaas and cup-
reus are always white with a few dark bands, while in caprius they
are always dark with white spots. Again flavigularis agrees with klaas
and cupreus.

5. The females of cupreus and of klaas are always barred on the

underside (flavigularis even more so); not so in caprius.

6. The juvenal plumage of klaas, flavigularis, and cwpreus are
transversely barred from chin to vent; longitudinally streaked, espe-
cially on chin, throat, and breast in caprius.

7. The backs of young cupreus and klaas are similar in “‘style of
coloration,” but not in caprius. Just what this means is not clear,

_ but flavigularis is much more like young klaas than caprius above.

8. The form of the bill in klaas approaches that in cupreus, not
in caprius. Unfortunately no indication is given as to the differences

in bill form in the three, and I can find nothing in flavigularis that

differentiates it in this respect from any of them.

9. In the scapulars the color is more concentrated toward the
tips of the feathers, less extended basally, in klass and in cupreus
than in caprius. This is at best a small difference, but in it flavigularis
agrees with the first two species.

10. The barbules are broad in klaas, flavigularis, and cupreus, and
relatively narrow in caprius.

From this list of 10 “characters” it becomes evident that flavigularis
and klaas are closely related. The green gorget on the sides of the throat

in the adult males of the two is a striking item of similarity, and

20 U.S. NATIONAL MUSEUM BULLETIN 265

bridges the gap between them to the extent that the evolutionary
history of klaas requires little imagination to unravel.

The two remaining species, caprius and cupreus, are very different
from each other. The former is a common, widespread bird of the open
bush and tree-dotted grasslands, and the latter is much more of a
forest dweller. As we have already seen from van Someren’s tabulation
of characters and also from Berger’s (1955) internal anatomical
studies, cwpreus is closer to klaas than to caprius, which is rather
divergent from both. In an evolutionary sense, however, neither
poses any real difficulties of interpretation. They are both ‘‘climax”
species of the African section of the genus, just as in their ways
meyerit and ruficollis are in New Guinea and osculans is in the drier
parts of Australia.

Furthermore, it may be pointed out that the plumages of the
young birds and of the adult females of the African klaas, cwpreus, and
caprius are fairly similar in general pattern to those of corresponding
stages of the Asiatic maculatus. The yellow-bellied emerald cuckoo,
CO. cupreus, has become differentiated into four geographic races;
the didric cuckoo, C. caprius, has remained monotypic. Both have
migratory populations in southern Africa and resident ones (as far
as we know) in equatorial Africa.

To round out this discussion of plumages it may be noted that the
genus Chrysococcyx reveals a tendency to produce rufescent coloration,
both as a part of the normal plumage patterns of many of its com-
ponent species and also as an occasional, complete color phase.
Rufescent or hepatic plumage phases occur in different degrees of
frequency in a number of genera of cuckoos. This plumage, however,
has been found only in immature birds and has been described in the
Kuropean cuckoo, Cuculus canorus canorus, by many authors. It also
occurs in the closely related yellow-billed cuckoo of Africa, Cuculus
canorus gularis, but has not been noted in the other African species of
the genus (solitarius and cafer) or in the Australian Cuculus pallidus.
Enough examples of these three species have been preserved in
collections to make the absence of an hepatic phase a well-established
fact. I am not aware of such a rufescent plumage in the young of the
Asiatic species of Cuculus, but here further search may reveal it.

In the genus Cacomantis rufescent plumage is the regular, not the —
unusual or sporadic coloration. In view of the close phylogenetic —
connection between it and Chrysococcyz, it is suggestive to find this —
trend well developed there. It is possible to think of this situation as a —
basic one from which the occasional rufescent tendencies of the —
glossy cuckoos may have stemmed.

In the glossy cuckoos an hepatic plumage has been noted in two |
species, the violet cuckoo, C. zanthorhynchus, and the didric, C.

AVIAN GENUS CHRYSOCOCCYX 91

caprius. In the former species Hume (1875, p. 81) described an
immature bird from Upper Pegu with the entire head, neck, chin,
and throat pale, rusty rufescent with broad blackish-brown streaks
and with the upper parts of the body hair brown. In the British
Museum collection I examined a young example of this species
(B.M. 82-1-20-989) from Thayetingo that had the entire head,
above and below, cinnamon with longitudinal blackish streaks,
reminiscent of Cacomantis. In the didric cuckoo the hepatic phase
has been noted so far only in a few immature females. Such birds
are almost wholly bright cinnamon above on the head, nape, back,
wings, and tail; the feathers of the back and wings and the upper tail
coverts have some greenish crossbars, and the rectrices, greenish-
black ones.

In the case of still another glossy cuckoo, C. klaas, we find that
the females usually have some mixture of coppery-bronze on the top
of the head and the upperparts of the body and tail, but this varies,
apparently individually. Whether this may be looked upon as a
vestigial or, conversely, as an incipient, hepatic morphism is not clear.

It is necessary to stress that the term “plumage phase”’ is obviously
not the same in its implications in the cuckoos as in, for example,
the owls of the genus Otus. In the latter birds the phase persists
throughout the life of the individual and not only for the duration
of its immature stage.

The variable extent to which rufescent coloration normally occurs
in the tail feathers is a well-known character by which museum
taxonomers have long ‘‘keyed out” races and species of Australasian
glossy cuckoos. Thus, in C. malayanus we find the following racial
differences in this regard: some rufous on all the rectrices in russatus;
none or little on the outermost pair of rectrices but considerable on
the next three pairs in minutillus and poecilurus; none on the outer-
most pair but some on the next two pairs in malayanus. In the related
species, C. lucidus, the nominate, New Zealand race and the New
Caledonian subspecies, harterti, have no or very little rufous on the

next to the outermost rectrix, while the south Australian and Tas-

- manian race, plagosus, has a considerable amount of this color on
_ the inner web of that feather. In the allied C. basalis the basal two-

thirds of all but the outermost and the median pair of rectrices are
rufous. The tendency to produce rufescent pigment in parts of the
rectrices appears also in the females of the African species, klaas and
caprius.

The one place in the whole genus Chrysococcyx where the most

striking and most definite (invariable) production of this rufous
color has taken place is in the New Guinea highland species, C.

'

meyerii, in which the adult female has a bright-chestnut rufous patch

Pd U.S. NATIONAL MUSEUM BULLETIN 265

on the forehead and fore-crown, while the male has this area bright,
shining green. This unique pattern is quite different from aes
found in the rest of the group, but in a large, overall view it may be
looked upon as an intensified but morphologically restricted expres-
sion of what may have been a basic but unformulated tendency to
produce rufescent coloration in the Chrysococcyz stock. In this species
the basal half of the remiges are rufous, a condition not found in any
other member of the genus.

The other color character that shows much irregular variability
in the glossy cuckoos is the purplish or coppery-purplish tone that
appears at times to replace to a greater or lesser extent the greenish
color. This occurs as a relatively minor, subspecific character in
C. lucidus, in which the Australian race plagosus has the top of the
head and back of the neck purplish-bronze, instead of green as in the
typical New Zealand birds. The distinction between green and purple
becomes very marked, and the colors themselves are greatly brightened
and intensified in the two closely related Asiatic species, maculatus,
with glittering emerald plumage, and zanthorhynchus, where the
purple has been strengthened into a deep violet.

In this connection, we may recall that many years ago Walden
(1874, pp. 137-138) described a male zanthorhynchus molting into the
deep amethystine color of the adult plumage. He noted that some of
the feathers of this individual “appear to have changed from green
to amethystine without having been moulted. Thus the basal part of ©
one of the median rectrices is more or less green, while the remainder
is of a mixed amethystine and greenish hue. Its fellow rectrix, a.
new feather not fully grown, is coming in of a pure amethystine |
colour. Several of the upper tail coverts are green at their base . . .”..
Walden concluded that the old feathers eau change from green |
to purple through abrasion or by fading, but this remains to be»
demonstrated.

Inasmuch as a number of digressions from the presentation of the »
relationships of the existing species have been permitted in the above’
survey, it may be well to recapitulate the whole history of the genus:
very briefly. It appears that there were three major branchings of!
evolutionary lineages in the history of the glossy cuckoos, with’
considerable but less striking speciation in the stock prior to the’
first, between the first and the second, between the second and the |
third, and after the third of these major changes. In the original |
stock, the closest living representative of which is malayanus, rela-.
tively small morphological divergences resulted in what we know’
today as lucidus, basalis, and ruficollis, and, with a greater degree:
of superficial change, osculans. Then came the first branching, char-’
acterized by a trend toward much more brilliant iridescence in the
male and toward sexual dimorphism in the adult plumage. The

AVIAN GENUS CHRYSOCOCCYX 23

result of this we see today in meyerzi of the highlands of New Guinea.
This trend was continued in the development of the two species of
Asia, maculatus and zanthorhynchus, and, later, in that of the four
African species. However, between meyerw and the Asian and African
forms a new, important character arose, involving a remarkable
change in the pattern of the ventral plumage in the young. In all
the species from malayanus through meyerii, the young have the
midventral underparts unmarked, uniform, pale brownish or grayish;
in the young of the Asiatic and African species the underparts are
heavily crossbarred. From the early stock with this character two
species, maculatus and santhorhynchus, evolved. In spite of their
external, visually great difference (green in the one and violet in
the other) they are closely related forms.

At this point there is a great gap in the picture, the four African
species being quite different from the Asiatic and Australian ones, but
of these four, flavigularis and klaas seem not too distantly related to
maculatus, and, as we have seen, they possess so many characters in
common with cupreus that it becomes evident that they too are closer
together in their phylogeny than their very distinct plumage patterns
might suggest at first sight. Similarly, caprius, while differing in a
greater number of details from each of the other three African species
than they do from each other, is not more than another very distinct
species of the same genus, the ancient steps leading to which have long
since disappeared.

On the whole, flavigularis and cupreus are largely sylvan in their
choice of habitat, klaas is more a bird of the open, tree-dotted bush-
veldt (although it does enter into the peripheral forest zones), while
caprius is an open-country bird. The two Asiatic species, maculatus
and zanthorhynchus, and to a very large extent, klaas, are parasites on
sunbirds, while caprius is much more inclined to use the nests of a
great variety of weaverbirds as repositories for its eggs, although it
does utilize sunbirds as hosts at times, just as klaas occasionally para-
sitizes weavers. Nothing is known of the host choice of flavigularis;
those of cupreus include weavers, shrikes, flycatchers, warblers, wag-
tails, and sunbirds, a most heterogeneous assemblage.

The external morphological characters most involved in the series
of changes are the following: 1. The degree of iridescence in the
plumage, which is only moderately well-developed in malayanus,
lucidus, basalis, and rujficollis, almost entirely lost in osculans, and
highly developed in the remaining species, with its acme of develop-
ment in cupreus. 2. The amount and distribution of rufous coloration
in the tail feathers in the species forming the earlier part of the history
of the group—malayanus, lucidus, basalis, rujicollis, and meyerit. 3.
The change from unmarked to a heavily barred ventral-plumage pat-
tern in the young; unmarked in malayanus, lucidus, basalis, osculans,

24 U.S. NATIONAL MUSEUM BULLETIN 265

ruficollis, and meyerii; heavily crossbanded in the others. 4. Sex di-
morphism in the adult plumages, well developed in the species be-
ginning with meyeri, on through maculatus and szanthorhynchus, and
the four African species (where it is less striking in caprius than in the
other three). 5. The relative length of the tail, longest in the African
species, with its maximum in cupreus. 6. Total size, smallest in meyerii,
largest in osculans, cupreus, and caprius. 7. Differential width of the
bill, as exemplified in the sympatric Australian species, lucidus and
basalis.

There are also, as we shall see later in this study, remarkable changes
in the coloration of the egg shells; here the picture is incomplete be-
cause we still have no information about the eggs of three of the species,
rujicollis, meyerir, and flavigularis (to say mothing of the eggs of some
of the races of some of the other species).

One point calls for some further clarification. In this summary the
results of the study have been outlined as if the relative chronology
of the species is certain and simple. It is not, and I must emphasize
the speculative, inferential aspect of these conculsions. To make the
reconstructed picture of the history of the group more comprehensible
to the readers of this report, personally unfamiliar with these birds,
it has been necessary to minimize the tentative nature of some of the
steps involved. The reader must be aware of the difference between
verbal presentation and scientific proof. On the other hand, the cir-
cumstantial evidence of the current 12 members of the genus Chryso-
coccyx points to the arrangement here outlined. A diagrammatic
representation of their relations, given below, suggests a certain
amount of multidirectional radiation, or cladogenesis, not a simple
progression from ‘‘primitive”’ to “more advanced.”

_-12,caprius

7. maculatus

8. xanthorhynchus 5 ruficallis

___d.basalis

Bt eae a 1. malayanus—__2. lucidus
6. meyerii A osculans

Figure 2. Apparent relationships within the genus Chrysococcyz.

AVIAN GENUS CHRYSOCOCCYX 25

Figure 3. Probable evolutionary dispersals of Chrysococcyx: 1. dispersal, from
Malaysian area to Australia and New Zealand, facilitating the differentiation
of lucidus, basalis, ruficollis, and osculans; 2. secondary movement, to New
Guinea with the development of meyeriz; 3. third dispersal, to southern Asia
with the development of maculatus and zanthorhynchus; 4. fourth dispersal, to
Africa with the differentiation of flavigularis, klaas, cupreus, and caprius.

Migratory behavior

In an evolutionary study such as this, migratory behavior poses
two separate problems. The first is the evolution of migration paths
and habits within the group; the second has to do with the effects of
seasonal movement on further evolution within the members of the
genus. A number of authors have emphasized the role migratoriness
plays in gene dispersal and have stated that it tends to reduce the
chances for subspeciation by mixing up the populations from several
breeding areas while in the common nonbreeding, ‘‘wintering” grounds
each year. Mayr (19638, pp. 417-418) has mentioned the high incidence
of monotypic species in the migratory North American warblers, Pa-
rulidae, as a case in point. He has also noted that the equally migratory
buntings, Emberizidae, on the other hand, show great geographic—or
racial—variability, but suggested that this may be due to the fact
that they are ground-living birds, perhaps more critically exposed to
selective pressures by predators and by microclimates than are the
largely arboreal Parulids. The glossy cuckoos are largely arboreal, but
they do not present a clear correlation of monotypy with migratoriness
or, on the other hand, of polytypy with sedentariness. Thus, three
species (ruficollis, meyerii, and flavigularis) are monotypic and non-
migratory; four others (basalis, osculans, maculatus, and caprius) are
monotypic and migratory; the most highly polytypic species (mal-

267-562—68——3

26 U.S. NATIONAL MUSEUM BULLETIN 265

ayanus) is nonmigratory; one (lucidus) is polytypic with two of its
four races migratory and two sedentary; two others (klads and cupreus)
are partly migratory and slightly polytypic; the remaining one
(canthorhynchus) is polytypic, but its migratoriness, although not yet
known, seems slight and partial.

In the tropics migration of more than very local movement is
indulged in by relatively fewer kinds of small land birds than is the
case in the temperate areas. Cuckoos, as a family, are among the most
migratory of land birds, and in the glossy cuckoos, which are primarily
tropical in their distribution (although extending into southern, sub-
tropical areas or even south-temperate regions in New Zealand,
southern Australia, Tasmania, and southern Africa), we find every
conceivable degree of migratory behavior, from none at all to some
of the most outstanding geographic movements known, involving
twice-yearly flights of more than 2000 miles nonstop over open seas.

Something of the degree to which migratory behavior occurs in the
cuckoos may be realized by a few statements culled from the literature.
In New Zealand Hutton (1900, p. 215) noted that the only regular
summer visitors (i.e., breeding visitors) to New Zealand are the two
parasitic cuckoos that occur there (Chrysococcyx lucidus lucidus and
Urodynamis taitensis). All the other small land birds that breed in
those islands are completely sedentary inhabitants of their indi-
vidual habitats. A few years later W. L. Sclater (1906, pp. 14-21)
estimated that, of the 814 species of birds then known to occur in
southern Africa south of the Zambezi, 731 were resident and only 21
were considered to be African migrants, as distinguished from Eurasian
winter visitors. Of these 21, no fewer than 9 were cuckoos (all
parasitic).

Aside from emphasizing that as a family cuckoos are prone to
migratoriness, these observations also strongly suggest that the
cuckoos came to these southern-subtropical and temperate areas
from the tropics and that they did not originate in those breeding
areas that they still annually desert during the nonbreeding season.
In other words, their present ‘‘wintering” ranges give us some sug-
gestive clues as to the areas from which the birds long ago extended
their distribution. However, it must be stated by way of caution that
this idea, if followed too literally, could present some difficulties that
cannot be explained in terms of the contemporary picture. Thus,
C. lucidus lucidus of New Zealand migrates to the Solomon Islands
for its ‘‘winter” season. If we were to assume from this that lucidus
was originally a Solomon Islands bird, we would have to explain why
neither it nor any other glossy cuckoo breeds in those islands today.
The climate, the vegetation, the presence of potentially suitable hosts
(although there are no Gerygone warblers, there are fantails, Rhipi-
dura—used as a host by C. malayanus russatus—and a number of

AVIAN GENUS CHRYSOCOCCYX QE

Meliphagids) are all such as would make the islands suitable for the
glossy cuckoos. It is not easy to account for their disappearance as
breeders in the Solomons, as would be necessary if we were to assume
that they once were there.

On the other hand, Fell (1947, p. 513) took the opposite view and
considered that if the southern, breeding range of C. l. lucidus and C. l.
plagosus were considered to be the old home of the two subspecies,
then their present migration routes, corresponding as they do with
the southeast trade winds, might be looked upon as a consequence of
the direction of these strong air movements. He went on to suggest
that one might consider the ancestors of these birds (typical lucidus)
to have been sedentary New Zealand birds, just as two other races of
the species (layardi and harterti) are sedentary to this day, “and that
the migratory habit arose as a consequence of recent glacial conditions
rendering New Zealand inhospitable in winter. A similar history
might have occurred in Tasmania... .”

It still seems to me more probable that the southern races of lucidus
were tropical in origin and then spread southward to their present
breeding ranges from which they returned to lower latitudes each
year. To say, as Fell does, that New Zealand is inhospitable in the
winter can only mean that it is inhospitable to a tropical or semi-
tropical bird.

Before discussing the migratory habits of each of the glossy cuckoos
it is necessary to recall that in the case of parasitic birds such as these
the adults may leave the breeding area long before the young of the
year and that the latter have little or no contact with the former
until they meet in the “wintering” grounds. In other words, the birds
of the year cannot possibly have any guidance, either directly or
indirectly, from older individuals of their own kind. Thus, Dove
(1925, pp. 43-44) noted that in Tasmania the adults of C. lucidus
plagosus and of C. basalis leave for the north about the end of Febru-
ary, but that the young of the year remain well into April. In discuss-
ing the New Zealand nominate race of C. lucidus, Mayr (1932) was
moved to write that ‘‘the migration of this species is very amazing,
and requires a perfect functioning of the entire ‘instinct’ appara-
tus. . . . On the average the young birds depart . . . later than the
adults. Nobody shows them the migration route, as their foster
parents (Gerygone and Rhipidura) are sedentary. . . .”

One other aspect of migratoriness should be mentioned before we
review the picture in each species of Chrysococcyz. We shall see that
in a number of these species part of the population is migratory and
part is not. In the case of three African species, klaas, cupreus, and
caprius, that breed in South Africa as well as in the equatorial portions
of the continent, the southern populations are definitely migratory
while their more northern relatives are not. Inasmuch as there is no

28 U.S. NATIONAL MUSEUM BULLETIN 265

evidence that the more meridional breeders are ecologically or geo-
graphically separated from the more northern ones, it is not possible
to assume that they are isolated into nonintercommunicating gene
pools. Because of this it becomes necessary to describe migratory
behavior in these species as partial. As pointed out in my earlier
study of a very similar situation in the crested cuckoos of the genus
Clamator (Friedmann, 1964, p. 76), partial migration is a term used
originally for European and North American species in which some
individuals are regularly migratory while others, breeding in the same
area, are nonmigratory, resident birds. Strangely enough, the tendency
toward migratoriness is not necessarily constant throughout successive
years of the life of an individual bird, and apparently it is not necessar-
ily an inherited character. This opens the way for a species to increase
its range by the migratoriness of some of its members, who the follow-
ing season or in the following generations become sedentary in their
recently established areas of occupancy.

The above considerations lead directly to, and help to elucidate,
the situation as we find it in the first species to be examined, C.
malayanus. This cuckoo, with 11 subspecies, ranges from the Malay
peninsula, from Patani southward, Sumatra, and the Philippines
(Negros, Mindanao, Basilan, Tawi Tawi, Bongao), Java, Borneo,
Celebes, the Lesser Sunda Islands, Babar Island, Biak, the western
Papuan Islands (Weigeu, Misol), New Guinea, the Aru Islands,
Vulcan, Dampier, and Fergusson Island, to the Moluccas (Hal-
maharea, Ternate, Buru, Ceram, Goram, Amboina), the Tenimber and
Kei Islands, to northern Australia (Cape York peninsula, Arnhem
Land, the Kimberly district of northwestern Australia, and northern
Queensland). In most of that range it is, so far as known, nonmigratory,
but there is some reason for thinking that one population, the race
minutillus (northwestern Australia, Arnhem Land, and northern
Queensland) may be partly migratory. Mayr (1939, pp. 128-129) and
Deignan and Amos (1950, pp. 167-168) have shown that specimens
obviously referrable to minutillus have been taken on the islands of the
Lesser Sunda and the Molucca group (where there are resident races),
rufomerus in the Lesser Sundas, and crassirostris in the Moluccas.
It is known that minutillus is present throughout the year in its
known breeding area of northern Australia, where specimens have
been taken in all months of the year except August and September,
and there is no reason for doubting that, if search were made, they
would be found in those two months also. The existence of minutillus
specimens from the Lesser Sunda Islands, taken in February, April,
May, August, September, October, November, and December, raises
a question as to what evidence there really is for migratory behavior in
this race. It cannot be resident in these islands sympatrically with
rufomerus, or in the Moluccas along side of crassirostris, and still be

AVIAN GENUS CHRYSOCOCCYX 99

a race of the same species. Deignan has suggested that it might be
necessary to consider rufomerus and crassirostris as a separate specific
group, but this seems unlikely, since the only diagnostic character they
have in common and in which they differ from the other forms of
malayanus is a deep, metallic, bluish-black subterminal area on the
central tail feathers.

It would seem (and present knowledge does not permit a stronger
word) that minutillus may be partly migratory, that these wandering
individuals are not breeding birds in the areas to which they roam, or,
less likely, that minutillus may have achieved a status of genetic
distinction enabling it to “invade” the ranges of rufomerus and of
crassirostris without danger of phenotypic swamping. Actually, the
whole history of C. malayanus with its high degree of geographic mor-
phism suggests that it must have been a geographic ‘‘expander’’ or
migrant, but that its members remained as sedentary ‘founder’
groups in the various islands it had encompassed in its expansion.

In C. lucidus we have another polytypic cuckoo, with four races,
two of which are highly migratory (luctdus and plagosus) and two
resident where found (harterti and layardi). Much is known of the
movements of the two migratory races, as may be seen from the
following summary, based largely on the data supplied by Mayr (1932)
and more recently and more fully by Fell (1947). The accompanying
map isfrom Van Tyne and Berger (1959, p. 185) based on Fell’s report.

= NORFOLK I.

SUMMER Loe
RANGE
(lucidus)

Fieure 4. Migration of two races of Chrysococcyz lucidus (ex Van Tyne and Berger)

30 U.S. NATIONAL MUSEUM BULLETIN 265

Typical /ucidus breeds in New Zealand and Chatham Islands, possibly
on Norfolk and Lord Howe Islands, but the detailed data all have to
do with New Zealand. The birds begin to leave there late in January
with the main migratory exodus in February, a few stragglers delaying
their departure until March and even early April, with occasional
wintering birds left behind. They begin to return there in mid-Septem-
ber, with the bulk of the birds arriving in October and the latest
definite migrant record being November 5. Their nonbreeding grounds
are in the Solomon Islands, where the earliest arrivals have been
reported on March 16 and the latest departures on September 25.
Their migration route, however, is not yet known with certainty.
Mayr (1932, pp. 2-5) wrote that ‘‘on their way from New Zealand to
the Solomon Islands these birds could travel either via New Caledonia
and the New Hebrides, or via the Australian coast and eastern New
Guinea. For the former route, which would be nearer and more direct,
there is no evidence. All the specimens collected in New Caledonia and
the New Hebrides are layardi.’’ Fell (1947, p. 512) wrote that the data
available to him indicated that birds leaving New Zealand in February,
March, and April flew “ ... northwest from various headlands
across the Tasman Sea via Norfolk or Lord Howe Islands, and then
northward to the Solomons. The complete lack of specimens from
New Caledonia and New Hebrides, although other subspecies are
well known there, seems to show that the New Zealand subspecies
cannot normally use that route, if ever. Fig. 7 shows the suggested
route as also that probable for the Tasmanian subspecies C. 1. plagosus,
which winters in islands from Lombok to New Guinea. The routes of
the two subspecies are roughly parallel, C./. lucidus being displaced
about 25° east of the other. The routes seem to correspond roughly
with the direction of the South-east Trade Winds. It seems then that
the cuckoos are wind-borne from their respective southern breeding
lands to their tropical wintering places—and on the return flight are
headed into the wind. On neither flight do they fly across the wind....”
Van Tyne and Berger’s map (fig. 4) shows an amazing direct migration
path over 2000 miles of open ocean. While Fell’s statement is correct
as a general statement, this does not rule out the possibility of some
individuals of typical /ucidus migrating by way of New Caledonia. As
a matter of fact, there is one such record, recently reported. Galbraith
and Galbraith (1962 p. 35) found that one of Layard’s old specimens
from Ausevata, New Caledonia, collected on April 26, 1877, is lucidus
and not, as previously assumed, layardt.

The race plagosus, which breeds in southern Australia and in Tas-
mania, winters in the Lesser Sunda Islands (Lombok, Flores, Wetar),
in New Guinea, and in the Bismark Archipelago. Its migratory path
apparently covers a broad front across much of Australia to New

AVIAN GENUS CHRYSOCOCCYX 31

Guinea and the islands to the west of it. Because it does not cross
great expanses of open water its migration may seem less spectacular
than that of typical Jucidus. Yet it would seem likely that much of the
vast expanse of the arid country of the Australian interior would offer
little to a bird of passage and that plagosus may well cover much of it
without pausing.

The other two races of C. lucidus are nonmigratory, C. lucidus
layardi in New Caledonia, the Loyalty Islands, New Hebrides, Banks
and Santa Cruz Islands; C. lucidus harterti in Rennell and Bellona
Islands.

The next species, C. basalis, is highly migratory. It breeds in Tas-
mania and southern Australia and “winters” in the Sunda Islands
from Java to Sumbawa, but has been recorded also from the Malay
Peninsula, Sumatra, Borneo, the Natuna and Kangean Islands,
Christmas Island (in the Indian Ocean), and Celebes; it has been noted
on migration in the Aru Islands and in the Cape York Peninsula. It
appears from the above that it veers generally farther to the north-
west in its northern, postnuptial journeying than does C. lucidus pla-
gosus, with which it is largely sympatric as a breeder.

Since the next species, C. ruficollis, is nonmigratory, we pass on to
the following one, C. osculans, which is at least partially migratory.
The literature on this point gives the impression that, at least in
southern Australia, the bird does definitely leave its breeding range
at the end of the season, returning there at the start of the next one.
Gilbert (1935, p. 22), wrote that in New South Wales the black-eared
cuckoo was regularly and “completely migratory.”’ By *‘completely”’
he apparently intended to convey the thought that its migration was
more definite and obvious to the local observer than was that of
basalis and lucidus (plagosus), both of which species he described as
incomplete, but regular, migrants. Peters (1940, p. 28) was unable to
learn much about osculans, writing that the extent to which it is mi-
eratory was uncertain, but noting that it had been recorded from the
Aru and Kei Islands and from Batjan. It appears to ‘‘winter’’ in the
Moluccas, according to van Bemmel (1948) and Mayr (1953), also to
a considerable extent in northern Australia. Being essentially a bird
of drier areas than the other species of Chrysococcyz, it may winter as
well in parts of central Australia, where its presence would be undis-
closed since there are no observers to report it.

The New Guinea mountain species, C. meyerii, is apparently non-
migratory, even in an altitudinal manner. Coming now to the two
Asiatic species, C. maculatus and OC. zanthorhynchus, the former is
definitely migratory, the latter possibly slightly or only partly so,
Even where zanthorhynchus is migratory, its movements are largely
unrecorded. The little emerald cuckoo, C. maculatus, breeds in the

a2 U.S. NATIONAL MUSEUM BULLETIN 265

highlands from Kumaon through Assam, southeastern portions of
Tibet, and Szechwan to Hupeh, and south to Burma, Yunnan, and
Annam. It has been recorded in winter or on migration in India,
Hainan, Cochinchina, the Malay Peninsula, and Sumatra. The violet
cuckoo, C. zanthorhynchus, occurs from Assam, southwestern Yunnan
and southern Annam, south to eastern Bengal, the Malay Peninsula,
Siam, Cochinchina, the Andaman and Nicobar Islands, Sumatra, the
Lingga Archipelago, Java, Borneo (including Banguey Island), the
Natuna Islands, and the Philippines (Luzon, Mindoro, Samar, Cebu,
and Basilan, possibly Palawan). Being a small bird of the treetops, it
generally goes unobserved; several observers have told me that it was
only occasionally that they found or collected this cuckoo.

These two small, brilliantly colored cuckoos seem in every way so
closely related that it is somewhat unexpected to find that they differ
as they do in their migratory behavior. It seems that zanthorhynchus,
with a geographic race, amethystinus, in the Philippines, and another
possibly dubious one, bangueyensis, on Banguey Island off the north
shore of Borneo, may originally have been more of a geographic
expander than maculatus, but that its outlying populations became
sedentary and, in time, became subspecifically differentiated.

The yellow-throated cuckoo, C. flavigularis, is a nonmigratory bird
of the western African forests. The other three African species are all
partly migratory—regularly so in their southern populations, all of
which regularly desert their South African breeding areas at the close
of the season and pass the nonbreeding months in the tropical portions
of the continent.

Of the remaining three African species, C. klaas is the least con-
sistent in its migratoriness. The didric, C. caprius, and the yellow-
bellied emerald, C. cupreus, have very definite dates of arrival and
departure in Africa south of the Zambesi, but klaas is considerably
less precise. Thus, Clancey (1964, pp. 221-222) wrote that in Natal
and Zululand klaas was “almost wholly migratory, the majority only
on the southern breeding grounds between the months of September
and April . . .,”’ but that many overwinter there. Similarly, Benson
(1940, p. 402; 1942, p. 212) was aware of even a greater percentage of
overwintering individuals in Nyasaland, which caused him to con-
clude that in that country klaas had no regular migration. In eastern
equatorial Africa, in Kenya and Uganda, Jackson (1938, pp. 503-509)
concluded that klaas was subject to partial or local migration. Although
it is not clear from his account if part of his apparent uncertainty of
the bird’s local seasonal movements was due to the annual arrival of
“wintering” birds from South Africa, this might have been the case.
Farther north, in Ethiopia, Benson (1942, p. 212) found klaas to have
no regular migration, as contrasted with caprius. White (1965, p. 186)

—————EEE

a

AVIAN GENUS CHRYSOCOCCYX 33

summarized the data by calling the species “largely resident, but
evidence of migratory movements in some areas... .”

Klaas’s cuckoo has been divided into three races, but one of these,
arabicus, known from very slight and unsatisfactory material, is only
doubtfully distinct; the other local race, somereni, from coastal
northern Kenya, seems more valid, but it is yet to be agreed upon by
all students of African ornithology. White (1965, p. 186) recognizes
neither arabicus nor somereni. A widely distributed species such as
klaas, largely resident in much of Africa from Senegal east to the
Sudan, Ethiopia and Somalia, south to Angola, Southern Rhodesia,
and the eastern Cape Province, might have become differentiated
into local races with minor morphological characters, but it has not;
somereni of north Kenya coastal belt is the only (and small) segment
of the total continental population that has become even slightly
different (more pronounced white edgings on the wing feathers). Its
uniformity can, however, hardly be attributed, even to a small degree,
to the partial migratoriness of Klaas’s cuckoo.

From the phylogeny suggested earlier in this report of the species
of glossy cuckoos, it would seem probable that klaas was originally
a forest bird like its close relative flavigularis. Its extension throughout
the bushveld and the tree-dotted parklands of much of Africa was a
secondary expansion. Only in the southern part of that expanded
range has it encountered seasonal changes marked enough to encourage
migratoriness.

The other two African glossy cuckoos, cupreus and caprius are
essentially similar in their seasonal movements to klaas, but, in
caprius particularly, their migration is more definite. Certainly in
areas south of the Zambesi the birds are present only in the breeding
season, arriving in October, and leaving in late April or early May.
In Natal Clancey (1964, pp. 220-221) found cupreus and caprius to be
summer residents (October to April) wintering in equatorial Africa,
with caprius arriving slightly earlier than cwpreus. In other parts of
Africa there are movements correlated with the rainy season. In my
earlier account (1949a, pp. 154-156) I noted that caprius was reported
as present in Sierra Leone only during the rains, arriving late in April,
and that in northern Nigeria its arrival was noted at the beginning
of the rains late in May. In Darfur caprius arrived in June and re-
mained until September; in Ethiopia it was also noted to occur only
during the rains, all birds having departed by the end of May. All
this suggests that the didric population of northeastern Africa shifts
about, to what location no one knows, at the time when the southern
breeding birds are flying northward. In Nyasaland it is a local migrant,
and in Zanzibar the resident population is increased by an influx of
birds in October and November.

34 U.S. NATIONAL MUSEUM BULLETIN 265

The migratory movements of klaas, cupreus, and caprius offer no
suggestive hints as to their respective loci of origin, except that they
began in the tropical areas of Africa, not in the southern part.

Premigrational swarming has been reported for two of the glossy
cuckoos. Chisholm (1935, p. 257) wrote of C. basalis that it has been
known to assemble in loose flocks of hundreds of individuals at Cape
York late in summer, ‘‘apparently bound for northern islands . . . .”
Ayres (1884, p. 224) was informed that toward the end of summer in
South Africa didric cuckoos (C. caprius) ‘were to be found in hundreds
along the Rhinoster river, near Cronstadt, where they were doubtless
collecting to migrate... .”

Courtship behavior

The courtship behavior of the glossy cuckoos has an evolutionary
interest in that it involves an atavistic behavior pattern that can
hardly be looked upon as other than a vestige of a distant past when
the primordial, ancestral cuckoo stock was not yet parasitic in its
breeding. The courting male has the habit of feeding the courted
female as if she were a fledgling, and the hen, in turn responds like a
young bird with fluttering wings and ruffled body plumage. This
pattern has been noted in four species—lucidus, klaas, cupreus, end
caprius, and since the first is fairly far removed from the other three
within the phylogeny of the species of Chrysococcyz, it may be assumed
that some of the other species will be found to have the feeding pattern
as well. In any event, there is no sign, nor is there any reason to expect
one, of an evolutionary development of this ethological trait within
the genus. It can only be looked upon as an ancestral habit occasionally
coming to the surface in these cuckoos. That it appears to be more
frequent in this group than in other genera of cuckoos is to be connected
with the fact that the glossy cuckoos are also more given to feeding
their fledged young than are other parasitic species. (Cuculus pallidus
is known to feed fledglings of its own kind, but other species of Cuculus
have not been reported doing so.)

To give some idea of how closely this courtship behavior parallels
that of fledgling feeding, we may take the observations of Haydock
(1950, p. 150) on the yellow-bellied emerald cuckoo, C. cupreus. He
saw a female perched on a bare branch of a largely defoliated tree,
which circumstances made observation much easier. A male was
perched on a branch a little higher up, calling loudly. He then flew
down to the female, and, with wings drooping and tail raised almost
vertically, he bowed and bobbed up and down in front of her and then
presented her with a large hairy caterpillar, transferring this directly

AVIAN GENUS CHRYSOCOCCYX 35

from his bill to hers. She accepted and swallowed this gift, the cock
bird calling loudly with his head held well back while she did so.
The entire performance was repeated shortly afterward, and then
coition was attempted but was not accomplished successfully.

In the case of C. klaas, Winterbottom (1939, p. 716) wrote that he
watched a pair of these cuckoos in Northern Rhodesia (now Zambia).
“The male, at least three times while we were watching, caught in-
sects, which it gave to the female. It seemed in a very excited state,
and hopped about her with a good deal of posturing, in which the
tail played a great part, now lifted aloft like a Wren’s, now depressed
and held sideways, but remaining silent ... .”

Beven (1943, p. 237) recorded similar behavior in the didric, C.
caprius, at Oudsthoorn, South Africa, on October 10. He noted that
the cock bird gave its usual call which was answered by the hen, the
latter becoming more insistent and frequent as the cock came closer.
This was seen a number of times, and each time the male brought and
offered caterpillars to the female. On one occasion the cock had to
wait with a caterpillar in his bill while the hen was still attempting to
swallow one he had given her previously. Jackson (1938, pp. 500—
502) also saw a male didric feeding a female several insects. ‘“‘On each
occasion, after presenting it, he faced the female with tail expanded
and erect, and bowed to her several times, first to one side and then
to the other... .”

Watson and Bull (1950, p. 226) noted courtship feeding in lucidus
in New Zealand, and even suggested that Hursthouse’s 1944 record
may have been a courtship affair and not a fledgling being fed by an
adult as originally described. Fitzgerald (1960, pp. 9-10) has given
other instances of courtship feeding in this cuckoo.

Inasmuch as it is not known how regularly and in what quantity
male glossy cuckoos offer food to their courtship partners, it is not
possible to estimate the nutrient quota involved for the hens. Royama’s
recent studies (1966) suggest that in some passerine species, especially
the great tit and the blue tit, the food supplied by the male is an
important supplement and plays a role in enabling the hens to pro-
duce their eggs. The present lack of information causes me to question
whether a similar importance exists in the glossy cuckoos, but the
possibility should be mentioned. Even if courtship feeding may act
as an added source of nutriment to the egg-producing hen, the be-
havior that underlies the habit is still to be looked upon as atavistic.

While courtship feeding is the most interesting and the most
revealing aspect of courtship behavior in the glossy cuckoos, it is
by no means the only one. Sedgwick (1955, p. 254) commented on a
“communal” display of C. lucidus, involving three birds on one occa-
sion and five on another, and consisting of a “slow pursuit through the

36 U.S. NATIONAL MUSEUM BULLETIN 265

crown of the tree and a rather slow raising and lowering of the wings,
often not in perfect synchronization, giving an impression of alterna-
tion or an attempt to balance.”

Similar communal display antics have been described for C. lucidus
by Edgar (1960, p. 134), by Fitzgerald (1960, pp. 9-10), and by Watson
and Bull (1950, p. 226), while Mathews (1918, p. 358) quoted his cor-
respondent Mattingley to the effect that he had noted six or seven
males simultaneously courting a single female, but not in a pursuit
flight like the cases described above. Mattingley noted that the cock
bird stretches its wings and then leans forward so that its metallic-
green back feathers show up clearly; “should the bird be in the sun-
light, the colour of its green back is most vivid, and appears like shot
silk. . . .’ A somewhat similar, but also different, courtship pose is
taken by the male of C. klaas, according to Winterbottom (1939, p.
716), who wrote that the ordinary display is given high up in trees, and
therefore is seldom witnessed. He saw a male, perched about a foot
from a hen, go through a series of twistings of the body from side to
side without moving its feet, with wings partly spread and drooped,
and with the tail partly spread. Here again it would appear that the
sideways movement of the courting male is a device for catching the
sunlight on its glossy feathers and making them shine during the
performance, like the more vertical movements of C. lucidus. It is
nothing new, but yet serves as a cause for perennial consideration that
special plumage colors are related to special movements by which
they are utilized in the ethology of their wearers.

Features of brood parasitism in

Chrysococcyx

Host selection and its evolution

In our discussion of the phylogenetic relationships of Chrysococcyx
to Cacomantis and Cuculus it was pointed out that the glossy cuckoos
probably developed out of the stock of which these groups are the
present representatives and that these genera are very similar in
many ways. It is not surprising, therefore, to find that their host
preferences are fairly similar also. This is particularly true for Caryso-
coccyx and Cacomantis. The hosts chosen by both are small, insectiv-
orous, passerine birds, and not a few of the species used are parasitized
by cuckoos of both genera. It is true that there have been reported
a very few instances of glossy cuckoos depositing their eggs in nests
of mousebirds, kingfishers, barbets, and woodpeckers, but some of
these may be erroneous, or, at best, may be looked upon as unusual,
if not accidental, host choices.

In areas where there are a number of kinds of parasitic cuckoos with

AVIAN GENUS CHRYSOCOCCYX 37

a considerable range in body size, as is true throughout the entire
range of Chrysococcyz, it might be expected that the small species,
such as the various glossy cuckoos, would tend to parasitize relatively
small birds and that larger cuckoos (Cuculus, Clamator, Urodynamis,
Eudynamis, ete.) would utilize primarily the nests of larger hosts.
In a very general way this is what we find, but in Asia and Australia
the presence of cuckoos of intermediate size of the genus Cacomantis
does complicate the situation to some extent. Still, it may be said
that there is a general tendency for size correlation between hosts
and parasites, although the limits are by no means rigid or constant.
This is different from what may be observed in Europe, where Cuculus
canorus, having no competition from other cuckoos, utilizes a great
range of small fosterers, many of them as small as the smallest hosts
of the small glossy cuckoos.

In Africa the glossy cuckoos (caprius, cupreus, and klaas) overlap
relatively seldom with the larger cuckoos of the genera Cuculus,
Clamator, Pachycoccyx, and Cercococcyx in their choice of hosts.
Strangely enough, the fosterers most frequently serving both Chryso-
coccyx and Ouculus are the wagtails, Motacilla, and these birds are
the only ground-nesting species used with any regularity by the
glossy cuckoos. The African glossy cuckoos use primarily species of
weavers, sunbirds, warblers, and flycatchers, and relatively seldom
parasitize babblers, thrushes, shrikes, and (except for Chrysococcyx
cupreus) bulbuls, to say nothing about hole-nesting starlings and such
larger birds as piapiacs and crows, used extensively by Clamator
glandarwus.

In India, Burma, Siam, and Malaysia, the glossy cuckoos (maculatus
and zanthorhynchus) do overlap in their host choice with Cacomantis
merulinus (less so with COacomantis variolosus), while in Australia
they (lucidus, basalis, malayanus, and osculans) find themselves in
regular and apparently not unequal competition for many of their
usual hosts with several species of Cacomantis (variolosus, pyrrho-
phanus, and castaneiventris), also with Cuculus pallidus, and, in New
Zealand, even with Urodynamis taitensis. To take but a single recent
study of the situation in Australia, Rowley (1965, pp. 274-275)
found the blue wren, Malurus cyaneus, to be parasitized by no less
than six species of cuckoos, three glossy cuckoos—lucidus (plagosus),
basalis, and osculans, by two species of Cacomantis (pyrrhophanus
and vartolosus), and by Cuculus pallidus.

Lest it may seem that excessive use of a single host species by
multiple parasites be self-defeating to the extent of seriously de-
pleting the host population, we may recall McGilp’s paper (1929,
p. 298) in which he discussed a situation ‘‘where the Spotted Scrub-
Wren (Sericornis maculata) [sic] is the foster-parent of several species

38 U.S. NATIONAL MUSEUM BULLETIN 265

of Cuckoo. I have worked this area for 10 years, and although hundreds
of Cuckoos have been reared during that period, I cannot see that the
Sericornis has diminished in numbers. In July and early August 75
per cent of the Scrub-Wrens’ nests contain one or more eggs of a
Cuckoo; later on in the season no Cuckoo eggs are noted. It appears
to me that Sericornis . . . rears a brood of its own to keep up their
numbers. Sericornis, in my experience, does not resort to the habit
of the Blue Wren (Malurus) of embedding the Cuckoos’ egg [in the
lining material, thus preventing the hatching out of the imposter’s
ege].”

To turn now to the problem of competition for hosts between the
various members of the genus Chrysococcyz, obviously more similar
to each other than they are to such different, although closely related
genera as Ouculus and Cacomantis, we may note that in areas where
two or more species of glossy cuckoos are sympatric as breeders there
is a considerable overlap in their host lists. Thus, in southern Asia
maculatus and xanthorhynchus utilize many of the same fosterers;
in Africa caprius and klaas overlap, but on the whole the former is
much more prone to use weavers as hosts while the latter uses sun-
birds and warblers primarily. The yellow-bellied emerald cuckoo,
C. cupreus, is apparently, so far as present knowledge goes, an indis-
criminate user of both groups of hosts but also lays often in the nests
of a bulbul, which the other two do not. Thus, weavers, Ploceidae,
account for 78.5 percent of all host records for caprius and only
13 percent for klass, with 35 percent for cupreus; warblers and fly-
catchers, Sylviidae, account for only 9.5 percent for caprius as com-
pared with 47.5 percent for klass, and with 15 percent for cupreus;
sunbirds, Nectariniidae, comprise only 5 percent of the host records
for caprius, 30 percent for klass, and 15 percent for cupreus. To these
last figures may be added the statement, made orally to me by Pitman,
that in his very extensive experience in Uganda he found sunbirds
to be the most frequent, almost the “regular,” hosts of klass and very
se dom of caprius.

In Australia basalis and lucidus (plagosus) overlap very considerably
in their host choices, more than half of their fosterers being parasitized
by both species, but they do exhibit some differences in that lucidus is
largely given to laying in spherical or domed nests rather than open
ones, while basalis uses all types equally. Thornbills of the genus
Acanthiza are the most frequently used hosts of lucidus (plagosus), and,
while they are often used by basalis as well, the latter cuckoo is more
partial to wrens of the genus Malurus. About 30 percent of all host
records of lucidus (plagosus) is with species of Acanthiza, in basalis
about 15 percent of the records involves thornbills, while Malurus
accounts for nearly 30 percent.

In the pages that follow are enumerated the known hosts of all the

AVIAN GENUS CHRYSOCOCCYX 39

glossy cuckoos. These data, together with the facts presented else-
where in this report as to the degree to which host specificity has de-
veloped and the degree to which host-egg resemblance has become
marked, form the relatively meager body of information that we may
interpret as evincing evolutionary trends toward progressive hetero-
geneity in host fixation among the various species of the group. To
meet the need for convenient terms by which to express these variations
of host selection, I proposed the following. Alloxenia (with alloxenic
as its adjective) may be used to describe cases where each species of
parasite uses different host species; homoxenia (with homoxenic as its
adjective) may be used for those cases where two or more kinds of
parasites make use of the same host species (1967, p. 175).

We are apt to think of Cuculus as having gone very far in adaptive
host-egg resemblance, but this is mainly because of the development of
host-specific “ gentes”’ in one species, Cuculus canorus. Certainly other
species of the genus do not show anything of comparable evolutionary
intensity, and it is to these less specialized parasites that the glossy
cuckoos may be compared.

Thus, it appears that malayanus is to a large degree bound up in its
reproductive pattern with Gerygone warblers, and that osculans has
come to specialize markedly on the speckled warbler, Chthonicola
sagittata (with the eggs of which its own have close similarity) and to
a lesser extent on the redthroat, Pyrrholaemus brunneus (to the eggs
of which its own bear a fair but less precise resemblance). While it has
been claimed by Baker and others that the eggs of maculatus and of
zanhorhynchus indicate adaptive accommodation to sunbird hosts,
particularly Aethopyga and Arachnothera, these eggs are not as highly
peculiar in their coloration as are those of osculans, and therefore per-
mit one to think their specialization may have been a matter of finding
hosts with fairly similar egg types rather than of developing an adap-
tive pattern in themselves.

The ease with which species such as lucidus and basalis have been
able to make use of the nests of recently introduced, nonnatural
hosts as Passer domesticus, Fringilla coelebs, Carduelis carduelis, or
Turdus merula argues against their having evolved rigid, or even
fairly obligatory, host preferences. As may be seen in the following
accounts of the several species of glossy cuckoos, there is evidence
for some host adaptation, but, with the exception of osculans, the
adaptation has not gone very far in a morphological sense. In the
relatively ‘‘advanced” African species, caprius and klaas, there is
strong indication of adaptive egg morphism to several divergent
hosts, implying an underlying fixity of host selection, which develop-
ment is not to be seen in what is known of the more “primitive”
malayanus, lucidus, and basalis groups.

40 U.S. NATIONAL MUSEUM BULLETIN 265

O. malayanus.

Host choices are known for less than half of the subspecies of this
cuckoo. In the case of three of them, only warblers of the genus
Gerygone have been reported thus far, and it is likely that these birds
are the most frequently used hosts. However, more complete knowl-
edge may reveal a less rigidly obligate dependence on Gerygone
than is suggested by the current data (e.g., in the northern Australian
and New Guinea races of the cuckoo, russatus and minutillus, it is
known that fantails and honeyeaters also serve as hosts). However,
in the case of russatus, where more observations have been put on
record than with minutillus, while 4 of the 11 fosterers are species of
Gerygone these 4 account for more than two-thirds of all host records,
with no fewer than 11 records for G. magnirostris and 5 for G. palper-
brosa. The former of these two species is also known to be the chief
host of the cuckoos of the subspecies minutillus.

The total reported fosterers are listed below.’

Race of Chrysococcyx malayanus*

Host

malayanus | russatus | minutillus | albifrons | poecilurus
Genygonemagninostris= = a eae ee xX Xi a's Lote te xX
Gerygone brunnetpectus_______--|-------- OX A ea xX
Gerigone Dal DebT08G== ae le eee x ON cia: el Ae ee
Geist ONC ROLLUCLCE Cm ee eee es ear | reeara a|| ear =n eee BNE | eine ea aecren| Ere es
Gerygone flavida ss 2 US Na ee EEE SAS eh Set AE Ae ee
Gerygone sulphurea__________-- Sig eee rn aga a || Bee pate Tee soa
Heteromyias cinereifrons______--|-------- DXcg Bary Nc Bie 3 A | pn
FED TOUT CORS CLO S Cee eee a | na Pe a2 Sh i ase lp er laa
Malurus melanocephalus_____---|-------- Rs [teeth ce mck alles wae [ees ee
WYCLEF LIS: COCA OWS 5 i es ges Bl aes Sp ne OR a ees aa ree | ee
Cyrtostomus jrenatus s= eC eee OXY NG ce EAS REAR OP PL
GlzciphalanaSc ata a ee ee | eee xX SL PE ac eee Sa
iMelinhagante 7177s neste el eee RA RNG SE Epes ete pel oe a etal hei
Meliphaga fascwgulariss= 222 |e 5. = OR if th oh ae aN, a eel ae

*No hosts yet known for the other races of this cuckoo.

1 For pertinent published data see: C. m. malayanus—Bromley 1941, pp.
140-146; Hoogerwerf 1949, p. 91; Makatsch 1955, p. 188; North 1895, p. 39;
1912, p. 28; C. m. russatus—Barnard 1926, pp. 6-7; Cayley 1950, p. 69; Chisholm
1925, p. 164; Le Souéf 1898, p. 59; Macgillivray 1914, p. 163; Mack 1930, pp.
302-303; Makatsch 1955, p. 189; Mathews 1918, p. 366; Schénwetter 1964, p. 571;
White 1915, p. 152; C. m. minutillus—Barnard 1914, p. 43; Campbell 1901, pp.
584-585; Cayley 1950, p. 70; Le Souéf 1898, p. 59; Makatsch 1955, p. 189;
Mathews 1914, p. 116; North 1895, p. 39; Schénwetter 1964, p. 571; White 1915,
pp. 153-154; C. m. albifrons—Bartels 1925, pp. 54-61; Hoogerwerf 1949, pp.
91-92; Makatsch 1955, p. 189; Schénwetter 1964, p. 570; C. m. poecilurus—Dodd
1913, pp. 190-191; Makatsch 1955, p. 189; Rand 1942, p. 313; Schénwetter 1964,
pp. 570-571.

AVIAN GENUS CHRYSOCOCCYX 4]

CO. lucidus.

The various races of this cuckoo are so unequally well known
that it seems advisable to list their known hosts separately. At this
point, however, it may be stated that all the known fosterers of its
various geographic segments are small insectivorous birds and that
the little warblers comprising the genus Gerygone appear to be the
most frequently chosen hosts. Fantails, robins, sunbirds, and honey-
eaters are also used, and even the introduced house sparrow, chaf-
finch, and blackbird are occasionally parasitized in New Zealand.

C. lucidus lucidus.

The nominate New Zealand race of the shining cuckoo has been
found to parasitize eight native and three introduced species of
birds.2 From the literature and the unpublished records kindly sent
me by their observers I have been able to amass some 58 cases of
parasitism, no fewer than 40 of which involved Gerygone igata, which
must, then, be considered the primary host. In this connection it
may be noted that in Australia the allied cuckoo race, C. 1. plagosus,
also uses Gerygone warblers but less frequently than it does thornbills
(Acanthiza).

The known fosterers are as follows:

Mohoua albicilla Whitehead

Gerygone igata Gray warbler

Gerygone albofrontata Chatham Island warbler
Petroica melanocephala Yellow-breasted tomtit
Miro australis Toutouwai

Rhipidura flabellifera Piwakawaka

Zosterops lateralis Gray-breasted silvereye
Turdus merula Blackbird

Anthornis melanura Bellbird

Passer domesticus House sparrow
Fringilla coelebs Chaffinch

C. lucidus layardt.

This race of the shining cuckoo is yet to be studied for its host
choice. The only statement in the literature is the assumption that
the chief host (!) is likely to be Gerygone flavolateralis (Makatsch,
1955, p. 188), which assumption is based on a mention by Mayr to
the effect that the distribution of C. 1. layardi is probably coordinated
with that of this “favorite’’ host.

2 For pertinent references to published records see: Buller 1888, p. 132; Cayley
1950, p. 70; Fulton 1910, pp. 392-408; Makatsch 1955, p. 188; Michie 1948,
p. 196; North 1912, p. 28; Oliver 1955, pp. 533-536; Parkin 1954, p. 207; Schon-
wetter 1964, p. 570; Stildolph 1939, pp. 84-93; White 1915, p. 152.

267-562—68—_4

42 U.S. NATIONAL MUSEUM BULLETIN 265;

C. lucidus plagosus.

The south Australian and Tasmanian race of the glossy cuckoo has
such a long list of recorded hosts, in contrast with much shorter list
for the New Zealand race and the absence of such lists for some of
the other subspecies of C. lucidus, that it seems advisable to discuss
it apart from its conspecific relatives. Thanks to the kind assistance
of numerous Australian observers I have been able to add to the
published data many additional cases of the parasitism of this cuckoo,
and now have a corpus of some 167 records involving 75 species.* No
attempt has been made to “break down’ these records to subspecies
because there exists no agreed-upon reference list of valid races of
Australian birds.

Of the 75 species included in the list 51 are known as fosterers of
this cuckoo on the basis of single records only; 12 others have been
reported twice as victims of the glossy cuckoo, 5 have been so noted
three times, 2 four times, and only 5 have been noted as fosterers
five or more times. In descending order of frequency the most im-
portant hosts are the following: yellow-tailed thornbill, Acanthiza
chrysorrhoa, 40 times; brown thornbill, Acanthiza pusilla, 13 times;
straited thornbill, <Acanthiza lineata, and_ buff-tailed thornbill,
Acanthiza reguloides, 7 times each; white-throated warbler, Gerygone
olivacea, 6 times; brown warbler, Gerygone richmond, and little
thornbill, Acanthiza nana, 4 times each; large-billed warbler, Gerygone
magnirostris, brown weebill, Smicrornis brevirostris, blue wren, Malurus
cyaneus, yellow-tipped diamond bird, Pardalotus striatus, and yellow-
winged honeyeater, Melwrnis novaehollandiae, 3 times each.

Of the 75 species (89 species and subspecies) of birds parasitized
by this cuckoo, one-third (25 species or 38 species and subspecies) are
not known to be used by C. basalis; all the others serve to unequal
degrees as hosts to both parasites.

Thornbills are thus the favorite hosts of this cuckoo, with the
Gerygone warblers next. Thornbills, with 8 species and 71 records of
parasitism, account for a little over 10 percent of all the hosts and
over 30 percent of all instances of parasitism. This figure is un-

3 For pertinent published references see: Barnard and Barnard 1925, p. 261;
Barrett 1905, p. 22; Campbell 1898a, pp. 144-146; 1901, pp. 582-583; Carter
1924, p. 228; Cayley 1950, p. 71; Chandler 1910, p. 245; Cornwall 1907, p. 192;
Dove 1916, p. 96; Fletcher 1915, p. 166; Hall 1898, p. 75; 1901, p. 128; Hanscombe
1915, p. 160; Hobbs 1961, p. 42; Howe 1905, p. 35; Jackson 1908, p. 202; Linton
1930, pp. 304-307; Littlejohns 1943, pp. 250-251; Makatsch 1955, p. 188; Mathews
1918, p. 359; Mattingley 1906, p. 66; McGilp 1929, p. 298; North 1893, p. 373;
1897, p. 26; 1912, pp. 20-23; Orton and Sandland 1913 p. 78; Ross 1913, p. 280;
Rowley 1965, pp. 274-275; Sandland and Orton 1922, p. 137; Serventy and
Whitell 1962, pp. 269-270; Smith 1926, p. 296; White 1908a, p. 31; 1910, p. 49;
1915, pp. 152-153.

AVIAN GENUS CHRYSOCOCCYX 43

doubtedly lower than it should be as the regular hosts are less in-
variably reported than are the seldom-used ones. In the Barrington
area of New South Wales, Lindsay Hyem (in. litt.) found that about
50 percent of all plagosus eggs were laid in nests of Acanthiza chrysor-
rhoa alone. The Gerygone warblers, with 6 species and 16 records,
account for 8 percent of all the hosts and 10.9 percent of all instances
of parasitism compiled.

Hirundo neoxena
Aylochelidon nigricans
Rhipidura fuliginosa
Rhipidura leucophrys
Myiagra rubecula
Myiagra cyanoleuca
Monarcha trivirgata
Microeca leucophaea
Petroica multicolor
Petrova goodenovi
Petroica phoenicea
Petrowa rhodinogaster
Melanodryas cucullata
Amaurodryas vitiata
Heteromyias cinererfrons
Poecitlodryas cervinwentris
Eopsaltria australis
Colluricina harmonica
Lalage sueurit
E’pthianura albifrons
Epthianura tricolor
Epthianura aurifrons
Gerygone olivacea
Gerygone richmondi
Gerygone flavida
Gerygone magnirostris
Gerygone mouki
Gerygone fusca

Smicrornis brevirostris
Acanthiza lineata
Acanthiza nana
Acanthiza mornata
Acanthiza ewingri
Acanthiza pusilla
Acanthiza uropygialis
Acanthiza reguloides

Welcome swallow
Tree martin
Gray fantail
Willie wagtail
Leaden flycatcher
Satin flycatcher
Spectacled flycatcher
Brown flycatcher
Scarlet robin
Red-capped robin
Flame robin
Pink robin
Hooded robin
Dusky robin
Gray-headed robin
Buff-sided robin
Southern yellow robin
Gray shrike thrush
White-winged trier
White-fronted chat
Crimson chat
Orange chat
White-throated warbler
Brown warbler
Fairy warbler
Large-billed warbler
Northern warbler
White-tailed (Western)
warbler
Brown weebill
Striated thornbill
Little thornbill
Western thornbill
Tasmanian thornbill
Brown thornbill
Chestnut-tailed thornbill
Buff-tailed thornbill

44 U.S. NATIONAL

Acanthiza chrysorrhoa
Acanthornis magnus
Sericornis maculatus
Sericornis lathami
Sericornis magnirostris
Calamanthus campestris
Chthonicola sagittata
Megalurus gramineus
Acrocephalus australis
Cisticola exilis

Stipiturus malachurus
Malurus cyaneus
Malurus callainus
Malurus splendens
Malurus leuconotus
Malurus melanocephalus
Artamus personatus
Artamus cinereus
Neositta chrysoptera
Climacteris picumnus
Pardalotus punctatus
Pardalotus striatus
Cyrtostomus frenatus
Zosterops gouldi
Zosterops lateralis
Melithreptus brevirostris
Myzomela nigra
Acanthornis tenuirostris
Acanthornis superciliosus
Gliciphila melanops
Meliphaga chrysops
Meliphaga leucotis
Meliphaga cassidix
Meliphaga ornata
Meliphaga penicillata
Meliornis novaehollandiae
Passer domesticus
Aegintha temporalis
Neochmia phaeton

C. basalis.

MUSEUM BULLETIN 265

Yellow-tailed thornbill
Serub-tit
Spotted scrub-wren
Yellow-throated scrub-wren
Large-billed scrub-wren
Rufous field-wren
Speckled warbler
Tattle grassbird
Australian reed warbler
Golden-headed fantail
warbler
Emu wren
Blue wren
Turquoise wren
Banded wren
Black-and-white wren
Red-backed wren
Masked wood-swallow
Black-faced wood-swallow
Orange-winged sittella
Brown tree-creeper
Spotted diamond bird
Yellow-tipped diamond bird
Yellow-breasted sunbird
Western Silvereye
Gray-breasted silvereye
Brown-headed honeyeater
Black honeyeater
Eastern spinebill
Western spinebil
Tawny-crowned honeyeater
Yellow-faced honeyeater
White-eared honeyeater
Helmeted honeyeater
Yellow-plumed honeyeater
White-plumed honeyeater
Yellow-winged honeyeater
House sparrow
Red-browed finch
Crimson finch

This species has the longest list of fosterers of any of the glossy
cuckoos, comprising 100 species of birds. This figure makes no attempt
to enumerate the subspecies involved, as the members of the Australian

AVIAN GENUS CHRYSOCOCCYX 45

checklist committee are still undecided about many of them. In the
following list the known hosts are merely listed by species in the order
of the 1926 Australian checklist, but with their nomenclature brought
up to date.‘

If one considers the large amount of raw data summarized in this
mere list, it is unfortunate to have to say that it does not convey a
very realistic picture in some important respects. Thus, while I have
had much kind cooperation from numerous Australian correspondents,
the records here amassed are frequently without detailed information,
and, as might be expected, it is often difficult to assess the frequency
with which certain species are parasitized. Unusual host records are
more apt to be reported than are repetitive ones of the frequent
hosts, and it is the latter that are really important in the biology of the
cuckoo. All in all, I have been able to compile some 386 records for
these 100 hosts, and of these 100 fosterers 26 are included on the basis
of only a single record apiece, 31 on the basis of two instances each, 16
on the basis of three records, 7 on the basis of four, and 20 are species
for which there are five or more known instances of parasitism.

The fairy wrens of the genus Malurus, the thornbills, Acanthiza,
and the robins, Petroica, are the most frequently used victims. Ten
species of Afalurus account for 109 records, or 28 percent of the total,
and of these the blue wren, M. cyaneus, leads with 62 records, or 16
percent of the total, with the black-and-white wren, M. leuconotus
second with 15 records. These figures are probably far too low, as only
a smaller percentage of records of commonly used hosts are published,
as compared to the fact that almost all unusual ones do find their way
into print eventually. Thus, in a recent letter Lindsay Hyem wrote
that in his area, near Barrington, New South Wales, basalis is very
selective, probably 90 percent of their eggs being laid in nests of the
blue wren. His statement is by no means unique, but he thought that

4¥For pertinent published references see: Barnard 1915, p. 43; Barnard and
Barnard 1925, p. 260; Campbell 1898b, pp. 151-154; 1902, p. 12; 1906, p. 197;
1913, p. 71; 1927, pp. 300-301; Carter 1903, p. 89; Cayley 1950, p. 70; Chenery
1924, p. 224; Chisholm 1920, pp. 315-316; Cleland 1924, p. 181; Cohn 1924, p. 76;
de Warren 1926, p. 78; Dickison 1928, p. 151; Dove 1924, p. 156; 1928, p. 224;
Gilbert 1935, p. 22; Givens 1925, p. 28; Hill 1907, p. 21; Hill 1903, p. 165; Hobbs
1961, p. 42; Howe 1910, p. 163; 1913, p. 190; 1928a, p. 216; Kikkawa and Dwyer
1962, p. 169; Leach 1928, p. 91; 1929, pp. 180-181; Littlejohns 1943, pp. 250-251;
Littler 1910, p. 85; Macgillivray 1914, p. 163; 1924, p. 15; Me Gilp 1921, p. 240;
1923, p. 279; 1925, p. 5; 1926, p. 278; 1935, p. 12; Mellor 1917, p. 18; North 1893,
p. 373; 1894, p. 327; 1895, p. 39; 1897, p. 26; 1912, p. 26; Orton and Sandland
1913, p. 78; Parsons 1918, p. 145; Ross 1913, pp. 280-281; 1919, p. 303; 1926,
p. 137; Rowley 1965, pp. 274-275; Sandland 1909, p. 150; Schnéwetter 1964, p.
569; Serventy 1929, p. 192; Serventy and Whitell 1948, p. 237; 1962, p. 268;
Smith 1926, p. 296; White 1910, p. 49; 1915, pp. 150-152; Whitlock 1910, p. 193;
Wilson 1914, p. 170; 1918, p. 235.

46 U.S. NATIONAL MUSEUM BULLETIN 265

possibly the fact that basalis is not numerous in his area may help to
maintain their host electivity to so high a degree. Several authors have
written of M/. cyaneus that it is the most frequent host for basalis,
some even calling it the “invariable” one. The thornbills, Acanthiza,
also with 10 species, account for 58 records, or 15 percent of the total.
The most frequently imposed upon of these birds is the yellow-tailed
thornbill, A. chrysorrhoa, with 18 records, followed by three other
species, A. pusilla with 11 records, A. uropygialis with 9, and A.
reguloides with 8. The robins of the genus Petroica, involving 5 species,
have been found to be parasitized 29 times, with the scarlet robin,
P. multicolor, leading with 11 records, the red-capped robin, P. good-
enovit With 10, the hooded robin, P. cucullata, with 4, the rose robin,
P. rosea, with 3, while the flame robin, P. phoenicea, is known by me
as a host on the basis of a single report.

Honeyeaters, family Meliphagidae, with 21 species involved, figure
on the list with a total of 39 records, with 5 reported instances for
one of the species, the tawny-crowned honeyeater, Gliciphila melanops,
4 cases for the yellow-winged honeyeater, Meliornis novaehollandiae,
and 3 or fewer for the rest.

As might have been expected, small passerine birds are the regular
hosts of this cuckoo, the one record for the diamond dove being an
obvious “freak’’ occurrence.

Diamond dove
Welcome swallow

Geopelia cuneata
EMrundo neoxrena

Microeca leucophaea
Rhipidura fuliginosa
Rhipidura rufifrons
Rhipidura setosa
Rhipidura leucophrys
Myiagra cyanoleuca
Seisura inquieta
Petroica multicolor
Petroica goodenovit
Petroica phoenicea
Petroica rosea
Petroica cucullata
Heteromyias cinereifrons
Eopsaltria australis
Epthianura albifrons
Epthianura tricolor
Epthianura aurifrons
Gerygone olivacea
Gerygone richmondi
Gerygone magnirostris

Brown flycatcher
Gray fantail

Rufous fantail
Northern fantail
Willie wagtail

Satin flycatcher
Restless flycatcher
Scarlet robin
Red-capped robin
Flame robin

Rose robin

Hooded robin
Gray-headed robin
Southern yellow robin
White-fronted chat
Crimson chat

Orange chat
White-throated warbler
Brown warbler
Large-billed warbler

AVIAN GENUS

Gerygone levigaster
Gerygone fusca
Gerygone mouki
Gerygone palpebrosa
Smicrornis brevirostris
Aphelocephala leucopsis

Aphelocephala castanewentris

Aphelocephala nigrocincta
Acanthiza lineata
Acanthiza ewingir
Acanthiza pusilla
Acanthiza nana
Acanthiza hamiltoni
Acanthiza robustirostris
Acanthiza uropygialis
Acanthiza reguloides
Acanthiza chrysorrhoa
Acanthiza tredaler
Sericornis lathama
Sericornis magnirostris
Sericornis maculatus
Sericorms frontalis
Hylacola pyrrhopygia
Hylacola cauta
Calamanthus fuliginosus
Calamanthus campestris
Chthonicola sagittata
Amytornis striatus
Megalurus gramineus
Acrocephalus australis
Cisticola exilis
Stiprturus malachurus
Malurus cyaneus
Malurus melanotus
Malurus callainus
Malurus splendens
Malurus leucopterus
Malurus leuconotus
Malurus lamberti
Malurus assimilis
Malurus amabilis
Malurus melanocephalus
Neositta chrysoptera
Neositta pileata

CHRYSOCOCCYX 47

Buff-breasted warbler
White-tailed (Western) warbler
Northern warbler
Black-throated warbler
Brown weebill

Eastern whiteface
Western whiteface
Banded whiteface
Striated thornbill
Tasmanian thornbill
Brown thornbill

Little thornbill
Red-tailed thornbill
Robust thornbill
Chestnut-tailed thornbill
Buff-tailed thornbill
Yellow-tailed thornbill
Sapphire (dark) thornbill
Yellow-throated scrub-wren
Large-billed scrub-wren
Spotted scrub-wren
White-browed scrub-wren
Chestnut-tailed heath-wren
Mallee heath-wren
Striated field-wren
Rufous field-wren
Speckled warbler

Striated grass-wren

Little grassbird
Australian reed warbler
Golden-headed fantail-warbler
Emu wren

Blue wren

Black-backed wren
Turquoise wren

Banded wren
Blue-and-white wren
Black-and white wren
Variegated wren
Purple-backed wren
Lovely wren

Red-backed wren
Orange-winged sittella
Black-capped sittella

48 U.S. NATIONAL

Dicacum hirundinaceum
Pardalotus punctavus
Cyrtosiomus frenaius
Zosterops gouldr
Zosterops lateralis
Melithreptus atricapillus
Melithreptus affinis
Melithreptus brevirostris
Myzomela sanguinolenta
Myzomela mgra
Acanthornis tenuirostris
Acanthornis superciliosus
Gliciphila melanops
Gliciphila albvfrons
Glicuphila indistincta
Gliciphila fasciata
Meliphaga lewvna
Meliphaga leucotis
Meliphaga chrysops
Meliphaga fasciogularis
Meliphaga ornata
Meliphaga pencillaia
Meliphaga flava
Phylidonyris pyrrhoptera
Meliorms novaehollandiae
Meliornis niger

Passer domesticus
Steganopleura bichenovvi
Taemopygia castanotis
Aegintha temporalis
Zonaeginihus guttatus
Poephiia cincia
Oarduelis carduelis
Chloris chloris

C. osculans.

MUSEUM BULLETIN 265

Mistletoe bird

Spotted diamond bird
Yellow-breasted sunbird
Western silvereye
Gray-backed silvereye
White-naped honeyeater
Black-headed honeyeater
Brown-headed honeyeater
Scarlet honeyeater

Black honeyeater

Eastern spinebill

Western spinebill
Tawny-crowned honeyeater
White-fronted honeyeater
Brown honeyeater
White-breasted honeyeater
Lewin boneyeater
White-eared boneyeater
Yellow-faced honeyeater
Mangrove honeyeater
Yellow-plumed honeyeater
White-plumed honeyeater
Yellow honeyeater
Crescent honeyeater
Yellow-winged honeyeater
White-cheeked honeyeater
House sparrow
Double-barred finch
Zebra finch

Red-browed finch
Spotted-sided finch
Black-throated finch
Goldfinch

Greenfinch

The black-eared cuckoo has been found to parasitize 11 species of

birds, as follows.°
Aphelocephala leucopsis

Eastern whiteface

5 For pertinent references see: Alexander, 1925, p. 237; Cayley 1950, p. 74;
Chisholm 1935, p. 69; Gilbert and Keane 1913, pp. 80-82; Hill 1907, p. 21; Howe
1928b, p. 259; Makatsch 1955, pp. 182-183; McGilp 1923, p. 279; 1956, p. 12;
North 1912, pp. 15-18; Orton and Sandland 1913, p. 78; Rowley 1965, pp. 274-
275; Sandland 1909, pp. 150-151; Schénwetter 1964, p. 567; Serventy and
Whitell 1962, p. 268; White 1908b, p. 158; 1915, p. 150.

AVIAN GENUS CHRYSOCOCCYX 49

Acanthiza chrysorrhoa Yellow-tailed thornbill
Sericornis lathami Yellow-throated scrub-wren
Sericornis maculatus Spotted scrub-wren
Pyrrholaemus brunneus Redthroat

Hylacola pyrrhopygia Chestnut-tailed heath-wren
Hylacola cauta Mallee heath-wren
Calamanthus isabellinus Rusty field-wren
Chthonicola sagittata Speckled warbler

Malurus cyaneus Blue wren

Malurus assimilis Purple-backed wren

The chief host, almost the exclusive one in some areas, is the speckled
warbler, Chthonicola sagittata, while the next most frequently victimized
fosterer is the redthroat, Pyrrholaemus brunneus. The dark, chocolate-
brown eggs of Chrysococcyx osculans match those of Chthonicola very
closely and those of Pyrrholaemus fairly well.

Of 53 instances of parasitism amassed from published as well as
from unpublished sources, 34 involved Chthonicola sagittata, 9 Pyrrhol-
aemus brunneus, 3 Acanthiza chrysorrhea, 2 Malurus assimilis, and 1
each for the other host species. In other words, 80 percent of the total
is of the two chief hosts, and a little over 60 percent refers to a single
one, the speckled warbler.

While there is no reason to question the suitability of the regular
hosts as fosterers of the young parasite, there is still little in the pub-
lished record to document the fact that they can and do rear them
successfully. As far as I have been able to learn, two of the less fre-
quent hosts, Malurus assimilis and Hylacola pyrrhopygia, have been
recorded explicitly as having been seen rearing and feeding nestlings
or recent fledglings of the black-eared cuckoo. From one published
source and two unpublished ones I have found documentation of
similarly successful rearings by the speckled warbler, Chthonicola
sagittata.

CO. maculatus.

The Asiatic emerald cuckoo is known to parasitize babblers, warblers,
and sunbirds, chiefly members of the latter two families.* The hosts
listed below are taken from the literature, and I have been obliged
to accept some of them as published. It should be kept in mind,
however, that the eggs of this cuckoo and of the violet cuckoo, C.
ranthorhynchus, are practically indistinguishable, and the original
identifications were based on little more than the mere fact that the
observerer noted only one of the two cuckoos in the area. As far as
the biological implications of host choice are concerned, this makes

6 For pertinent references to published records see: Ali 1962, p. 56; Baker 1907,

pp. 682, 684; 1908, p. 278; 1927, pp. 162-163; 1942, p. 195; Dewar 1925, p. 154;
Makatsch 1955, p. 186; SchGnwetter 1964, pp. 568-569; Smythies 1953, p. 325.

50 U.S. NATIONAL MUSEUM BULLETIN 265

little difference as these two cuckoos appear to use the same or a
very similar range of fosterers.
The recorded hosts of the little emerald cuckoo are:

Stachyris nigriceps Black-throated babbler

Stachyris ruficeps Red-headed babbler

Tesia cyanwwenter Dull slate-bellied ground
warbler

Bradypterus luteoventris Brown bush warbler

Cisticola quncidis Fantail warbler

Cettia fortipes Strong-footed bush warbler

Orthotomus sutorvus Tailor-bird

Phylloscopus reguloides Blyth’s leaf warbler

Seicercus castaneiceps Chestnut-headed flycatcher-
warbler

Aethopyga siparaja Yellow backed sunbird

Aethopyga gouldiae Mrs. Gould’s sunbird

Arachnothera longirostris Little spider-hunter

C. xanthorhynchus.

The violet cuckoo is still imperfectly known and will probably
continue to be so because of its preference for the higher branches of
trees where it is observed with difficulty. Eggs or young attributed to
it have been recorded with nine species of fosterers, chiefly warblers
and sunbirds, but also babblers and one flower-pecker.’ Because of
the close similarity of the eggs of this cuckoo and those of its close
relative C. maculatus and the overlapping of the ranges of the two,
the identifications of some of the egg records may be less than com-
pletely certain, but they are given here as identified by their collector-
observers.

All of the known hosts are involved with the nominate, mainland
subspecies of the violet cuckoo. So far no one has reported any eggs
or young of the Philippine race, amethystinus, or the Banguey Island
race, bangueyensis.

The hosts reported to date are:

Trichastoma abbottr Abbott’s babbler

Napothera epilepidota Small wren-babbler

Alcippe nipalensis Nepal babbler

Cisticola guncidis Fantail warbler

Orthotomus sutorius Tailor bird

Sercercus zanthoschistus Gray-headed flycatcher-warbler

7 For pertinent references to published records see: Baker 1907, p. 682; 1927,
p. 163; 1942, p. 195; Dewar 1925, p. 154; Hoogerwerf 1949, p. 91; Inglis 1908,
p- 681; Makatsch 1955, pp. 186-187; Schénwetter 1964, pp. 569-570; Smythies,
1953, p. 325.

AVIAN GENUS CHRYSOCOCCYX 51

Dicaeum agile Thick-billed flower-pecker
Aethopyga siparaja Yellow-backed sunbird
Arachnothera longirostris Little spider-hunter

It may be mentioned that Baker (1927, p. 163) considered Cisticola
as probably an “abnormal” fosterer, but he accepted the record as an
actual occurrence. Its nesting site is certainly different from the
arboreal situations used by the other hosts chosen by the violet
cuckoo.

C. klaas.

Klaas’s cuckoo is now fairly well known, insofar as many, but
casual, observations may be said to constitute an acquaintance with
a species. It resembles the didric, C. caprius, in many ways, and the
two are often ecologically sympatric. Like the didric, the Klaas’s
cuckoo evinces a wide range of choice of passerine hosts.®

Klaas’s cuckoo has been found to parasitize 59 species (80 species
and subspecies), 21 of which are also known to be victims of the didric.
However, aside from species recorded as hosts but a single time for
each of these two cuckoos, few of these fosterers are affected equally
often by both species of glossy cuckoos. In fact the tawny-flanked
longtail, Prinia subflava, recorded as a host of C. caprius 16 times
and of C. klaas 20 times, and the Cabanis weaver, Ploceus intermedius,
with 7 records as a host of the didric and 5 as a victim of Klaas’s
cuckoo, are the only two hosts that appear to be equally parasitized
by both cuckoos. The more usual picture seems to be that a bird known
to be a frequent victim of one of these parasites may be affected by the
other one occasionally. Thus, the masked weaver, Ploceus velatus, has
105 records of parasitism by C. caprius, but only a single record by C.
klaas. Similarly the red bishop, Hwplectes oriz, has been noted as a vic-
tim of the didric 77 times, of Klaas’s cuckoo only twice. The only
other hosts with more than a single record as host for each of the two

8 For pertinent references to published records see: Bannerman 1933, pp. 117—
119; Belcher 1930, p. 299; 1949, p. 19; Benson 1940, p. 402; 1946, p. 297; 1953,
p. 35; Benson, Brooke, and Vernon 1964, p. 56; Braun 1931, pp. 148-149; 1934,
p. 555; Chapin 1953, p. 725; 1954, p. 339; Chubb 1914, p. 63; Erlanger 1905,
p. 485; Friedmann 1949a, pp. 139-146; 1949b, p. 517; 1956, pp. 396-399; Grote
1924, p. 34; Haagner and Ivy 1906, p. 35; Holman 1947, p. 641; Jackson 1938,
pp. 503-504; Jerome 1943, pp. 100, 102; Joubert 1943, p. 5; Mackworth-Praed
and Grant 1957, p. 779; Mackatsch 1955, pp. 184-185; Masterson 1953, p. 51;
MacLeod, MacLeod, and Murray 1952, pp. 17, 22; Meneghetti 1944, p. 96;
Pitman 1957, pp. 3-6; Pringle 1946, pp. 368-369; Pringle 1948, pp. 155-156;
Roberts 1939, pp. 18-20; 1940, p. 143; Schmidt 1963, p. 176; Sch6nwetter 1964,
p. 567; Sclater and Moreau 1932, pp. 512-513; 1933, p. 403; Sheppard 1958, pp. 6-8;
Skead 1952, p. 12; 1954a, p. 87; Skinner 1929, p. 111; Sparrow 1936, p. 6; Stoneham
1952, p. 7; van Someren 1916, pp. 234, 384, 454; 1922, pp. 53; 1932, p. 277; 1939
p. 37; 1956, pp. 160, 358, 440-447; pp. 763-764; Vincent 1946, p. 59; Vincent
1934, Williams 1946, p. 138.

52 U.S. NATIONAL MUSEUM BULLETIN 265

glossy cuckoos are the paradise flycatcher, Terpsiphone viridis, witb
5 records for C. caprius and 10 for C. klaas, and the red-breasted sun-
bird, Nectarinia erythroceria, with 5 records for C. capriws and 22 for
C. klaas.

The list of hosts common to the two cuckoos includes 2 species of
Motacilla, 1 of Turdvodes and Parisoma, 2 of Cisticola, 1 of Prinia,
2 of Nectarinia, 1 of Cyanomiira, 1 of Plocepasser, 3 of Passer and of
Ploceus, 1 of Malimbus and 2 of Euplectes. The possibility of error in
the identification of the cuckoo eggs in some of these instances cannot
be ruled out, although I have been at some pains to eliminate records
that for one reason or another seemed uncertain. The eggs of caprius
and klaas are not always distinguishable with certainty.

The data on Klaas’s cuckoo comprise some 210 records of parasitism
on 59 species of birds. The three most important groups of fosterers are
as follows. Sunbirds (Nectariniidae) 85 records, or 40 percent of the
total number, involving 16 species, or 27 percent of all reported hosts;
warblers, flycatchers, and thrushes (Muscicapidae) 89 records, or 42.3
percent of total number, involving 25 species, or 42.3 percent of all re-
ported hosts; weaverbirds (Ploceidae), 27 records, or 12.8 percent of the
total number, involving 12 species, or 20.3 percent of all reported hosts.
These figures are in sharp contrast to those for the didric, where 81
percent of all instances of host choice was of weaverbirds; where only
9 percent of the cases was of warblers, flycatchers, or thrushes, and
only 4 percent was of sunbirds.

In descending order of frequency, the main hosts of Klaas’s cuckoo
are as follows: Chalcomitra senegalensis, 25 records; Nectarinia eryth-
roceria, 22; Prinia subflava, 20; Terpsiphone viridis, 10; Cinnyris afer,
9; Chalcomitra amethystina, 9; Apalis thoracica, 8; Batis capensis, 8;
Alseonax minimus, 8; Ploceus reichenowi, 6; Ploceus intermedius, 5;
Cinnyris venustus, 5; and Apalis flavida, 5. The mere number of records,
however, does not give a true picture of the relative frequency of par-
asitism of each host species, since these numbers are readily increased
as further study is given to any one particular host. At Kampala,
Uganda, Alseonar minimus was considered the commonest fosterer
by Pitman (in litt.), outranking the sunbirds for which I have com-
piled larger numbers of such records.

Klaas’s cuckoo agrees with the didric in that it has not been found
to lay its eggs in nests of terrestrial nesters (larks, typical pipits, etc.)
in treeless savannahs and also in that it usually avoids the nests of
bulbuls and babblers. There is a single record for a single species of
each of these families.

List of all known host species:

Motacilla aguimp Pied wagtail
Motacilla capensis Cape wagtail

AVIAN GENUS CHRYSOCOCCYX 53

Turdoides jardinet
Pycnonotus barbatus
Batis capensis

Batis molitor

Alseonar adustus
Alseonax minimus
Terpsiphone viridis
Terpsiphone perspicilata
Terpsiphone nigriceps

Myioparus plumbeus
Parisoma subcaeruleum
Daphorophyia castanea
Apalis thoracica

Apalis flavida
Hremomela rcteropygialis
Sylvietta rufescens
Camaroptera brevicaudata
Cisticola woosnamt
Cisticola erythrops
Cisticola cantans
Cisticola natalensis
Cisticola robusta
Cisticola fulvicapilla
Cisticola anonyma
Prinia subflava
Calamocichla rufescens
Sazxicola torquata
Lamprotornis caudatus
Zosterops senegalensis
Nectarinia erythroceria
Nectarinia famosa
Nectarinia kilimensis
Nectarinia tacazze
Nectarinia pulchellus
Cinnyris cupreus
Cinnyris venustus
Cinnyris afer

Cinnyris chalybeus
Cyanomitra verticalis
Chalcomitra amethystina
Chalcomitra olivacea
Chalcomitra rubescens
Chalcomitra senegalensis

Arrow-marked babbler
Yellow-vented bulbul
Cape puffback flycatcher
Chin-spot flycatcher
Dusky flycatcher
Pygmy dusky flycatcher
Paradise flycatcher
Cape paradise flycatcher
Black-headed paradise fly-
catcher
Gray tit-babbler
Tit babbler
Chestnut wattle-eye
Bar-throated warbler
Black-breasted bush-warbler
Yellow-rumped eremomela
Long-billed crombec
Gray-backed glasseye
Trilling grass warbler
Red-faced grass warbler
Singing grass warbler
Striped grass warbler
Stout grass warbler
Tawny-cap grass warbler
Chattering grass warbler
Tawny-flanked longtail
Rufous swamp warbler
South African stone-chat
Long-tailed glossy starling
Senegal white-eye
Red-breasted sunbird
Malachite sunbird
Bronzy sunbird
Tacazze sunbird
Beautiful sunbird
Coppery sunbird
Buff-breasted sunbird
Greater double-collared sunbird
Lesser double-collared sunbird
Green-headed sunbird
Amethyst sunbird
Olive sunbird
Ruby sunbird
Scarlet-chested sunbird

U.S. NATIONAL MUSEUM BULLETIN 265

Chalcomitra veroxi
Anthreptes collaris
Passer domesticus
Passer melanurus
Passer iagoensis
Plocepasser mahali
Ploceus velatus
Ploceus reichenowt
Ploceus cucullatus
Ploceus intermedius
Malimbus rubriceps

Euplectes orrx
Euplectes nigroventris
Emberiza cabanisi

Mouse-colored sunbird

Collared sunbird

House sparrow

Cape sparrow

Rufous sparrow

White-browed sparrow-weaver

Masked weaver

Reichenow’s weaver

V-marked weaver

Cabanis’s masked weaver

Yellow-winged redheaded
weaver

Red bishop

Zanzibar red bishop

Cabanis bunting

Of the 59 hosts tabulated above, 30 figure in the list on the basis
of single records; 11 others are birds for which I have been able to
learn of two instances each; two have been reported as fosterers of
Klaas’s cuckoo 3 times and two others 4 times each.

C. cupreus.

The emerald cuckoo of Africa has been found to parasitize a good
number and a wide variety of small passerine birds. Data are available
on 60 instances of its parasitism, involving 34 species of hosts (42
species and subspecies).®

Unlike C. caprius, which is primarily parasitic on weavers, and C.
klaas, which affects sunbirds and warblers more than any other birds,
the present species cannot be said to favor one particular family of
hosts. The most frequently reported fosterer is a bulbul, Pycenonotus
barbatus, for which there are nine records; then, with four records
apiece, are a weaver, Ploceus cucullatus, a sunbird, Nectarinia erythro-
ceria, and a flycatcher, Terpsiphone viridis; following these, with
three records each, are a shrike, Dryoscopus cubla, two sunbirds,

For pertinent references to published records see: Bannerman 1933, p. 114;
Benson 1952, pp. 443-445; 1953, pp. 35, 113; Benson and Benson 1947, pp. 4-5;
Benson, Brooke and Vernon 1964, p. 56; Benson and White 1957, p. 44; Chapin
1939, p. 203; Cole 1957, p. 190; Connell 1959, p. 140; Friedmann 1949a, pp. 124—
128; 1949b, pp. 516-517; 1956, pp. 393-395; Fry 1961, p. 271; Guichard 1950,
p. 168; Haagner and Ivy 1906, p. 35; Jackson 1938, pp. 499-500, 1412; Keulemans
1907, pp. 245-247; Mackworth-Praed and Grant 1952, p. 509; Makatsch 1955,
p. 184; Miles 1951, p. 4; Pitman 1929a, pp. 98-99; Priest 1936, 1948; Pringle,
1946, p. 368; Pringle, 1948, pp. 155-156; Roberts 1939, pp. 18-20; 1940, p. 143;
1963, p. 185; Ryves 1959, p. 175; Schénwetter, 1964, p. 568; Skead 1951, p. 197;
Sparrow 1936, pp. 5-7; van Someren 1958, pp. 23-24; van Someren 1932, p. 277;
1939, p. 37; 1956, pp. 159, 251, 272, 287; van Someren and van Someren 1949,
p. 95; Vincent 1965, pp. 81-86; Vincent 1934, p. 761; Winterbottom 1951, p. 27;
Woodward and Woodward 1899, p. 117.

AVIAN GENUS CHRYSOCOCCYX YS)

Chaleomitra olivacea and Chalcomitra senegalensis, and a weaver,
Ploceus reichenowi; 3 species are known from two records each, while
the other 21 have been noted as victims of this cuckoo but once.

The present list of fosterers is weighted, probably unduly, on the
side of species occurring in the open woodlands and brush country
rather than in the dense forests, but the emerald cuckoo is much more
of a forest dweller than is either the didric, OC. caprius, or Klaas’
cuckoo, C. klaas. Observation is generally more difficult in heavy
forests than in more open country, and, consequently, fewer nests are
found in the former areas. It may be expected, however, that in time
an increasing number of purely sylvan birds will be added to the host
catalog of the emerald cuckoo. Thus, not a single species of forest
bulbul has yet been found to be victimized, but, if we consider the
frequency with which Pycnonotus barbatus is affected in the more open
areas, it would seem probable that some of its sylvan relatives also are
imposed upon.

In light of the above there is only little to be gained by estimating
the proportional role of the various passerine families in the economy
of the emerald cuckoo. It is true that our present data suggest that
the weaverbirds (Ploceidae), with 12 species of hosts out of the total
34 and 20 instances out of the 60, rank first; the sunbirds (Nectarinii-
dae), with 6 species of bosts and 14 instances come second; the warbler,
flycatcher, and thrush assemblage (Muscicapidae), with 6 species and
9 records, and the bulbuls, also with 9 records but only a single host
species, come next, followed by the white-eyes (Zosteropidae), with
4 species and 4 records. However, when more complete data on forest-
dwelling birds become available, it will undoubtedly be necessary to
alter this arrangement.

The currently known hosts are as follows:

Motacilla capensis
Pycnonotus barbatus
Parisoma subcaeruleum
Droptrornis fischeri
Platysteira peltata
Horizorhinus dohrni
Terpsiphone rufiventer
Terpsiphone viridis
Prinia subflava

Oriolus larvatus
Dryoscopus gambensis
Dryoscopus cubla
Zosterops virens
Zosterops ficedulinus
Zosterops griseovirescens
Speirops leucophaea

Cape wagtail

Yellow-vented bulbul
Tit-babbler

White-eyed slaty flycatcher
Black-throated wattle-eye
Dohrn’s thrush babbler
Red-bellied paradise flycatcher
Paradise flycatcher
Tawny-flanked longtail
Black-headed oriole
Gambian puff-backed shrike
Puff-backed shrike

Green white-eye

Principé white-eye

Annobon white-eye

Principé speirops

56

Nectarinia erythroceria
Nectarinia kilimensis
Cinnyris chloropygius
Cinnyris reichenowr
Chalcomitra olivacea
Chalcomitra senegalensis
Passer melanurus
Ploceus xanthops
Ploceus reichenowt
Ploceus cucullatus
Ploceus ocularis
Ploceus subaureus
Ploceus velatus
Malimbus malimbicus
Amblyospiza albifrons
Euplectes ortiz
Euplectes hordeaceus
Pholidornis rushiae

U.S. NATIONAL

MUSEUM BULLETIN 265

Red-breasted sunbird
Bronzy sunbird
Olive-bellied sunbird
Reichenow’s sunbird
Olive sunbird
Scearlet-chested sunbird
Cape sparrow
Jameson’s golden weaver
Reichenow’s weaver
V-marked weaver
Spectacled weaver
Golden weaver
Masked weaver
Crested malimbe
Grosbeak weaver
Red-bishop
¥ire-crowned bishop
Tit-weaver

C. caprius.

The didric cuckoo is the best known of the African species of the
eroup. Over many years I have been able to amass some 426 records
of its parasitism on a total of 67 species (84 species and subspecies)
of hosts.'°

10 For pertinent references to published records see: Bannerman 1933, p. 114;
Bates 1905, p. 96; Belcher 1924, p. 3; 1930, pp. 109-110; Benson 1952, p. 443;
1953, p. 35; Benson and Benson 1949, p. 165; Benson, Brooke, and Vernon 1964,
p. 56; Benson and Pitman 1961, p. 161; Benson and White 1957, p. 44; Bergh
1943, p. 121; Chapin 1939, p. 199; Chubb 1914, p. 63; Distant 1897, p. 143;
Farkas 1962, p. 28; Fischer 1880, p. 190; Friedmann 1949a, pp. 163-178; 1949b,
p. 517; 1956, pp. 400-403; Fry 1961, p. 275; Grote, 1912, p. 522; Haagner and
Ivy 1906, p. 37; Haydock 1950, p. 150; 1951, p. 3; Hoesch and Niethammer 1940,
pp. 169-170; Holman 1947, p. 641; Hunter 1961, pp. 55-63; Ivy 1901, pp. 26-27;
Jackson 1938, pp. 500, 803, 1817, 1852; James 1921, p. 185; Joubert 1943, p. 5;
Layard 1875-84, p. 155; Makatsch 1955, pp. 185-186; Markus 1961, p. 33; 1964,
p. 123; McLachlan and Spence 1957, p. 126; Miles 1951, p. 4; Moltoni and
Ruscone 1940, pp. 17-18; Mouritz 1910, p. 68; Nicholson 1897, pp. 142-148;
Ottow and Duve 1965, p. 435; Packenham 1948, p. 100; Paterson 1945, p. 226;
Petit 1899, pp. 66-67; Pitman 1929b, p. 99; 1934, pp. 210-211; 1957, pp. 3-6;
Plowes 1945, pp. 113-114; 1946b, p. 271; Priest 1929, p. 33; 1936, p. 275; Pringle
1948, p. 155; Reed 1953, pp. 138-140; Reichenow 1881, p. 16; 1894, p. 111;
Roberts 1913, pp. 32-33; 1926, pp. 233-234; 1939, pp. 17-18; 1940, p. 143; Rowan
and Broekhuysen 1962, p. 28; Serle 1954, p. 55; Skead 1947, pp. 1-42; 1951,
p. 197; 1952, pp. 4-5; 1954b, p. 102; Sparrow 1936, pp. 6-7; Stoneham 1926,
p. 65; 1929, p. 269; Swynnerton 1916, p. 284; van Someren 1916, pp. 233, 384,
454; 1918, p. 268; 1956, pp. 236, 464; van Someren and van Someren 1945, p. 44;
Vaughn 1930, p. 11; Verheyen 1953, p. 315; Vincent 1947, p. 201; Winterbottom
19515 15;

AVIAN GENUS CHRYSOCOCCYX 57

The didric is generally absent from treeless grasslands, and it is
by this fact that we may explain the absence of terrestrial open grass-
land nesting birds, such as larks and most pipits, from the list of hosts.
Hole-nesting birds, such as starlings, are also left alone by this cuckoo,
and so too are the estrildine waxbills and their relatives.

Approximately 81 percent of all parasitized nest records or records
of hosts feeding recently fledged didric cuckoos have to do with weaver-
birds, Ploceidae, with a total of 346 instances divided among 36
species (or 50 species and subspecies). Of these records 198 are of
species of the single genus Ploceus, involving 19 species (31 species
and subspecies), while a single species of the genus, P. velatus, accounts
for 105 records by itself, about a quarter of all the known instances
of didric parasitism. Two other species, P. capensis and P. cucullatus,
have 21 and 23 records, respectively. However, the bird with the
second largest number of observed instances of parasitism is, not a
species of Ploceus, but the red bishop, Huplectes orix, for which some
77 records have come to my notice. Next in frequency of choice as a
fosterer is the Cape sparrow, Passer melanurus, with 43 records, or
almost 10 percent of all the known instances of didric parasitism.

Flycatchers, warblers, and thrushes, forming the large family
Muscicapidae, account for 38 records, or about 9 percent of the total,
distributed among 16 species, or 23 percent of ali recorded hosts. Of
this assemblage the warblers of the genus Prinia, with 3 species, have
been reported as hosts 18 times, 16 of these instances being of the one
species, Prinia subflava.

Sunbirds provide about 9 percent of the known hosts (six species)
with 17 records, or about 4 percent of the total known instances. It
may be noted that Klaas’s cuckoo, C. klaas, is much more partial to
sunbirds as hosts and correspondingly less so to weaverbirds than is
the didric.

Wagtails and pipits (Motacillidae) play a somewhat lesser role in
the parasitism of the didric. There are in my files 12 reports of three
species of this family serving as hosts to the cuckoo. A single one
of these refers to a typical pipit (Anthus), the others concern two
species of wagtails (Motacilla), birds less apt to be denizens of the
open grasslands. Two species of Fringillidae account for seven records
of parasitism or about 1.7 percent of all the cases. Other families of
birds are less frequently used by the parasite, and all but one of them
are passerine birds, the one exception being the mousebird, Colius
colius, for which a single record (Ottow and Duve, 1965, p. 435) is
known to date.

Of the 68 species of hosts, more than half (39 to be exact), are
known in this relationship on the basis of single reported instances;
6 have been so recorded only twice; 3 each, three and four times;

267-562—68——5

58 U.S. NATIONAL MUSEUM BULLETIN 265

and 17 have been found to be hosts on five or more occasions. These
last are to be looked upon as the regular hosts of the didric cuckoo,
and they may be listed here in order of the frequency with which
they have been so recorded: Ploceus velatus, 105 times; Euplectes oriz,
77; Passer melanurus, 43; Ploceus cucullatus, 23; Ploceus capensis, 21;
Prinia subflava, 16; Ploceus nigerrimus, 8; Motacilla capensis, 7;
Chalcomitra senegulensis, 7; Ploceus intermedius, 7; Malimbus ru-
briceps, 6; Huplectes hordeaceus, 6; Emberiza flaviventris, 6; Motacilla
agump, 5; Nectarinia erythrocerta, 5; Ploceus pelzelni, 5; Ploceus
ocularis, 5.
List of all known host species:

Colius colius

Motacilla aguimp
Motacilla capensis
Anthus novaeseelandiae
Turdoides jardinet
Parisoma subcaeruleum
Bradornis pallidus
Bradornis microrhynchus
Terpsiphone viridis
Turdus oliwaceus
Cercomela familiaris
Cossypha caffra
Dessonornis humeralis
Calamocichla leptorhyncha
Camaroptera brachyura
Cisticola erythrops
Cisticola robusta
Cisticola ruficeps

Prima flavicans

Prima subflava

Prinia maculosa

Lanius collaris

Oriolus larvatus
Nectarinia kilimensts
Nectarinia erythrocerva
Cinnyris chloropygius
Chaleomitra amethystina
Chalcomitra olivacea
Chalcomitra senegalensis
Plocepasser mahali
Passer domesticus
Passer melanurus
Passer iagoensis

White-backed mousebird
Pied wagtail

Cape wagtail

Richard pipit
Arrow-marked babbler
Tit-babbler

Pale flycatcher
Small-billed flycatcher
Paradise flycatcher
Olive thrush

Familiar chat

Cape robin-chat
White-throated robin-chat
Tana swamp warbler
Glass-eye

Red-faced grass-warbler
Stout grass-warbler
Redpate grass-warbler
Black-chested longtail
Tawny-flanked longtail
Spotted longtail

Fiscal

Black-headed oriole
Bronzy sunbird
Red-breasted sunbird
Olive-bellied sunbird
Amethyst sunbird
Olive sunbird
Scarlet-chested sunbird
White-browed sparrow-weaver
House sparrow

Cape sparrow

Rufous sparrow

AVIAN GENUS CHRYSOCOCCYX 59

Passer griseus

Passer eminibey
Petronia superciliaris
Amblyospiza albifrons
Ploceus baglafecht
Ploceus pelzelni
Ploceus ocularis
Ploceus capensis
Ploceus subaureus
Ploceus xanthops
Ploceus heuglina
Ploceus bojert
Ploceus zanthopterus
Ploceus castanops
Ploceus taeniopterus
Ploceus intermedius
Ploceus velatus
Ploceus cucullatus
Ploceus nigerrimus
Ploceus melanocephalus
Ploceus jackson
Ploceus rubiginosus
Ploceus tricolor
Malimbus rubriceps

Quelea cardinalis
Euplectes gierowi
Euplectes nigroventris
Euplectes hordeaceus
Euplectes oriz
Euplectes capensis
Euplectes albonotatus
Euplectes ardens
Emberiza flaviventris
Fringillaria capensis

Grey-headed sparrow
Chestnut sparrow
South African rock sparrow
Grosbeak weaver
Baglafecht weaver
Slender-billed weaver
Spectacled weaver
Cape golden weaver
Smith’s golden weaver
Jameson’s golden weaver
Heuglin’s weaver
Mombasa golden weaver
Zambesi brown-throated weaver
Nile brown-throated weaver
Nile masked weaver
Cabanis’ masked weaver
Masked weaver
V-marked weaver
Vieillot’s black weaver
Black-headed weaver
Golden-backed weaver
Chestnut weaver
Yellow-mantled weaver
Yellow-winged redheaded
weaver
Cardinal dioch
Gierow’s bishop
Zanzibar red bishop
Fire-crowned bishop
Red bishop
Yellow bishop
White-winged whydah
Red-collared whydah
Golden-breasted bunting
Cape rock bunting

In addition to the 67 species of hosts listed above, the following
brief statement must suffice to place on record the races affected,
where more than one subspecies of a given host is known to be
parasitized:

Motacilla capensis: races capensis and wellsr

Prinia subflava: races graueri, immutabilis and affinis
Passer melanurus: races melanurus and vicinus

Ploceus ocularis: races ocularis, crocatus, and suahelicus
Ploceus subaureus: races subaureus and aureoflavus
267-562—68——6

60 U.S. NATIONAL MUSEUM BULLETIN 265.

Ploceus velatus: races velatus and nigrifrons

Ploceus cucullatus: races cucullatus, collaris, bohndorffi, graueri,
nigriceps, and spilonotus

Ploceus nigerrimus: races nigerrimus and castaneofuscus

Ploceus melanocephalus: races capitalis, duboisi, and dimidiatus

Euplectes hordeaceus: races hordeaceus and craspedopterus.

Host Specificity

Avian brood parasites fall into three categories as far as host
specificity is concerned: those that exhibit no such specificity, those
that are specific in their parasitism as individuals only, and those
in which the entire species is specific on one host species or a small
group of related hosts. Members of the first category deposit their
eggs in any available and generally suitable nest, regardless of the
particular species of victim involved; this is true not only of the brood
parasite as a species but also of each of its included individuals.
These may be said to be nonhost specific.

Parasites whose individual members tend to lay all their eggs in
nests of a single species of host, although the hosts may differ for
many of these conspecific parasites, may be described as exhibiting
individual host specificity. In some such cases there may be adaptive
development of egg morphs with resemblance to the eggs of frequent
fosterers. In the case of the European cuckoo, the best known example
of individual host specificity, the individually host-specific producers
of these ovomorphs have been termed ‘‘gentes,”’ groups intermediate
between morphs and geographical subspecies. Southern (1954, p. 220)
considered that about half the species of parasitic cuckoos sufficiently
studied have been found to have, or are suspected to have, such
subdivisions. This conclusion seems to be an exaggeration and possibly
was derived by counting as species some of the Asiatic races of
Cuculus canorus, such as telephonus and bakeri, and putting them
together with other species that lay but a single egg type that matches
the eggs of its regular hosts (e.g., Cuculus optatus), It seems better
to consider the ovomorphic gentes of Cuculus canorus and of Cuculus
micropterus as the extreme of adaptive evolution rather than asa
widespread condition in the cuckoos. The condition in Chrysococcyz,
outlined below and in our discussion of egg morphism, helps to put
this in proper perspective.

The third group, characterized by specific-host specificity, comprises
species in which the individual host preferences of all the included
members are similar, with the result that the species of parasite is
restricted in its parasitism to a single species or to a small group of
similar species of hosts. It would seem (but cannot be proved) that in

AVIAN GENUS CHRYSOCOCCYX 61

some of the cuckoos’ specific-host specificity is an evolutionary out-
growth from an earlier individual host specificity.

All three stages of host specificity are to be found in the glossy
cuckoos. It must be said, however, that in such cases the ‘‘evidence”’
for nonhost specificity is an inference based only on the fact that in
many places egg collectors and other nest observers have recorded a
variety of parasitized nests without significant percentages of dupli-
cation of hosts within a limited area or over a limited time of observa-
tion. Careful, intensive field studies may reveal more actual or
incipient individual host-specific trends than these present records
suggest. Actually, we know that many brood parasites with a wide
range of host species tend to utilize only a fraction of them with marked
regularity. Thus, in the case of nonhost specific cuckoos, the lack
of observable individual host preferences seems due, not necessarily
to their definite absence, but to the fact that, while such preferences
or specificities may be present as a “‘background” situation, they are
rather easily ignored when a suitable nest of a different potential
host becomes available, particularly when nests of favorite hosts are
scarce. It may well be that some of these hen cuckoos have potential
individual host preferences, but that these have not become fixed or
ritualized to a degree where they impose an obligatory direction,
and hence they are not apparent to the observer—and this is all
that is implied when such cuckoos are described as nonspecific in
their host selection.

In two sympatric Australian glossy cuckoos, basalis and lucidus,
we find a difference in manner of host choice that may reflect one
factor under the influence of which individual host specificity may
have developed. C. lucidus very frequently (but not always) uses
spherical, or at least dome-shaped, nests while basalis appears to be
free from any such restriction, selecting both domed and open nests
equally. This means that lucidus is thereby rendered more limited in
its choice of hosts than is basalis. However, the number of available
fosterers as nest-builders in either category is still considerable, but
even within the domed-nesting species a difference exists in the list
of fosterers frequently imposed upon by the two cuckoos. Thus,
Serventy and Whitell (1962) write that basalis parasitizes the banded
whiteface, Aphelocephala nigrocincta, western warbler, Gerygone fusca,
blue wren, Malurus cyaneus, white winged wren, Malurus cyanotus,
blue and white wren, Malurus leucopterus, variegated wren, Malurus
lamberti, striated field wren, Calamanthus fuliginosus, Mallee heath
wren, Hylacola cauta, brown thornbill, Acanthiza pusilla, and yellow-
tailed thornbill, Acanthiza chrysorrhoa. Of these the two thornbills
(especially the yellow-tailed one) and the blue wren are also listed as

62 U.S. NATIONAL MUSEUM BULLETIN 265

common hosts of C. lucidus plagosus, but not the others, while the
spotted scrub wren, Sericornis maculatus, is recorded as victimized
by plagosus but not by basalis. On rare occasions both species of
cuckoos have been found to parasitize the same nest.

We may now turn to each of the nine species of Chrysococcyx of
whose breeding habits we have some knowledge to determine the
extent to which each exhibits host-specific trends.

1. C. malayanus: no information at all on the breeding habits for
6 of its races (aheneus, gungei, salvadorw, misoriensis, rufomerus, and
crassirostris); in 8 others (malayanus, albifrons, and poecilurus)
the only host records are for warblers of the genus Gerygone (G.
sulphurea for malayanus and albifrons, G. magnirostris for poecilurus),
but the total evidence is so slight that it cannot be said that other hosts
will or will not be found to be used; in two races (russatus and minutil-
lus) the Gerygone warblers are the most usual, but by no means the
exclusive, hosts, with some 13 kinds of warblers, honey-eaters, etc.
(Gerygone, Heteromyias, Cyrtostomus, Meliphaga, Ptilotis, and others)
recorded as victims of russatus and 4 as victims of minutillus.

2. C. lucidus: this species, in its various races, shows the whole
range of host selection from nonspecificity to individual host specificity
to specific host specificity. The importance of this variability merits
discussion here.

That specific, as well as individual, host specificity may both occur
in different geographic segments of the same species of parasite
is shown by the Pacific-island races of C. lucidus, which appear to be
so restricted in their host choice to Gerygone that their distribution
is correlated with, if not governed by, the presence of these little gray
warblers as breeders. Thus, in his description and discussion of
C. lucidus layardi, Mayr (1932, p. 7) was led to write that its distri-
bution “is apparently closely linked up with that of its foster parent,
Gerygone flavolateralis . . . . G. fl. correiae was found by the Whitney
Expedition on Mai, Epi, Lopeui, Ambrym, Malekula, Aoba, Gaua and
Vanua Lava. The collecting of one specimen of this cuckoo on Utupua
Island was a surprise. It is not known what species serves there as
foster-parent ... .”’ Similarly, in his account of C. Ll. harterti, Mayr
(1932, p. 8) wrote that the “occurrence of a Bronze Cuckoo on Rennell
Island is obviously due to the presence of Gerygone on the same
island ... .” Certainly this marked and exclusive degree of host
specificity is not true of the lucidus population that breeds in New
Zealand (typical lucidus), where two species of Gerygone (igata and
albofrontata) are the chief, but not the only, hosts, which are known
to include forms of Rhipidura, Petroica, and Zosterops as well. Even
less is this true of the populous segment of the species breeding in

AVIAN GENUS CHRYSOCOCCYX 63

much of Australia (C. 2. plagosus), for which no fewer than 75 kinds of
local hosts are now recorded. It causes one to ask if there are no
suitable fosterers other than Gerygone on Bellona, Rennell, Loyalty,
and other islands, and it also makes one wonder why no breeding
populations of either lucidus or malayanus have become established
in the Solomon Islands or in the Bismarks, where the elsewhere-
favorite hosts are to be found.

3. OC. basalis: the number of mere egg records in collections and
those mentioned in field observations give the impression that this
cuckoo is generally nonspecific in its host selection, with a long list
of 100 fosterers reported. However, intensive field studies may reveal
trends toward individual host specificities, as the following facts
suggest. One egg collector in Australia informed me that he had in
his personal collection some 15 sets of eggs, each with a single egg of
C. basalis, no less than 9 of which were of the blue wren, Malurus
cyaneus, and 7 of which came from one locality, indicating that in
that immediate area the basalis hens were more inclined to use the
nests of the blue wren than those of any other potential host species.
Furthermore, the large number of instances of blue wren parasitism
reported by Barrett (1905, p. 22), Campbell (1901), Cleland (1924,
p. 181), de Warren (1926, pp. 78-79), Dickison (1928, p. 151), Dove
(1928, p. 224), Givens (1925, p. 28), McGilp (1921, p. 240; 1926, p.
278), North (1912), Parsons (1918, p. 145), White (1915, pp. 150-152),
and many others have clearly demonstrated that of all the known
fosterers Malurus cyaneus is the favorite host of C. basalis. In the
Barrington area of New South Wales, Hyem (in dit.) thought that as
many as 90 percent of all basalis eggs were laid in nests of the blue
wren. Another observation suggestive of individual host specificity
in this cuckoo was reported by Cohn (1924, p. 76), who found six
nests of the red-capped robin, Petroica goodenovit, each of which had
an egg of C. basalis. “From the similarity of the eggs and the fact that
I saw only one Cuckoo near these nests, I feel reasonably certain that
the same Cuckoo laid all the eggs . . . .”’ Until further data become
available it is unprofitable to attempt any probing interpretations, but
the suggestion of specialized host trends is obvious.

4. ©. osculans: no definite observational data on individual hens,
but the large number of instances of parasitism on Chthonicola sagittata
and the close correspondence between the eggs of this host and those
of the cuckoo argue for the existence of frequent individual host
specificity on the speckled warbler. The fact that the species C.
osculans also parasitizes a number of other birds, even if less frequently,
indicates a degree of divergence from a one-host trend that amounts
to an absence of host specificity in some individuals of this cuckoo.

64 U.S. NATIONAL MUSEUM BULLETIN 265

5. C. maculatus: no reliable or even inferential information. The
similarity of its eggs to those of its Arachnothera host may suggest
a trend toward specificity, but there are no critical data.

6. C. zanthorhynchus: as in C. maculatus.

7. CO. klaas: meager data and the fact that no egg resemblance has
been developed with reference to the majority of its numerous species
of hosts make it difficult to argue for marked host specificity in this
cuckoo. However, Pitman (1957) examined 100 nests of Prinia subflava
at Broken Hill, Zambia, and found 7 of them to contain one klaas
egg each, all of one coloration type, suggesting that one, or a very few,
hens there were more or less specific on this longtail, or at least favored
it as a host.

8. OC. cupreus: no data other than the vague suggestion of possible
individual host specificity underlying the observable egg adaptation
toward two of its numerous hosts.

9. C. caprius: as indicated in our discussion of the egg morphism of
the didric cuckoo, the development of host-egg resemblance for two
of its commonly used fosterers, Huplectes oriz and Passer melanurus,
and the large number of instances of parasitism on each of these,
suggests a considerable frequency of individual host specificity in this
cuckoo. The absence of such adaptive coloration in those eggs laid in
the nests of a great number of its other hosts does not necessarily
indicate, however, an absence of host-specific trends in many other
didric hens. This is particularly true in the case of didrics parasitic on
masked weavers, as discussed below. Because intensive field studies
of African birds are still few in number, observations directly sug-
gestive of host specificity in didric parasites are relatively scarce, but
the following instances are pertinent.

R. A. Reed (in litt.) kindly sent me a transcript of his observations
made at ‘“Tongani,’”’ near Johannesburg, Transvaal. Over a period of
years he studied a number of colonies of red bishops, Huplectes oriz.
In the 1955 season he regularly inspected every nest in five colonies
of these birds, recording incubation and fledging periods. Not once
during the summer did he find a didric cuckoo egg or chick in any of
them, although adult didrics were commonly seen about there. These
same colonies had been heavily parasitized by the didrics the previous
year, but in 1955 the cuckoos concentrated on Cape sparrows, Passer
melanurus. This indicates that within one season several didric hens
were markedly specific on red bishops (1954), and that the next year
the same or, more probably, other didric hens were equally inclined
to use the nests of the Cape sparrow. In both seasons it seems some
hens were markedly host specific. A comparable case is that of G. Duve
(in litt.), also near Johannesburg, who found that some didrics, laying
plain blue eggs, were parasitic on red bishops almost exclusively.

AVIAN GENUS CHRYSOCOCCYX 65

Ottow and Duve (1965) presented a summary and interpretation
of Duve’s observations, pointing out that, although the red bishops
were parasitized very heavily (52 instances in the one small area),
other species of birds nesting nearby and known to be parasitized by
didrics in other localities (Prinia, two species of Ploceus, etc.) were
never bothered by the cuckoos. This suggests that the local didric
hens were rigidly fixed, or specific, on Huplectes orix. It was concluded
(p. 432) that each female caprius was restricted to a single host
species. That such host specificity is purely an individual matter is
supported by the fact that in other areas where both the didric
cuckoos and the red bishops are breeding the latter are not parasitized.
Thus, in the eastern Cape Province, Skead (1956, p. 125) reported
that his colony of red bishops was never parasitized, although adult
didrics were seen from time to time in the vicinity. Skead noted
Reed’s 16 records of parasitism on this bird from near Johannesburg
and emphasized the fact that his local cuckoos were not Huplectes
parasites,

Many years earlier I reported (Friedman, 1928, p. 37) that in the
northern Transvaal I had found in several instances didric cuckoos
appeared to have established “territories” around trees containing
colonies of masked weavers, Ploceus velatus, and that in four cases
their territories seemed restricted to single trees in an area where the
trees inhabited by the weavers were fairly widely separated—about
a quarter of a mile apart. These colonies contained but a single
species of weaver, from which it would follow that the parasite by
restricting its attentions to the colony in effect would be host specific.
In two of these colonies where a didric cuckoo was seen day after
day and at different times of the day I cut down and examined every
nest. “In the first case there were 37 nests; of these 20 were in use and
of these 4 contained a single egg apiece of the didric cuckoo. The
egos were so similar as to indicate that all were the product of the
same female. In the second case there were 28 nests; of these 18 were
in use and of these 3 contained an egg of the didric apiece, again
apparently the product of one individual” (Friedmann, 1949a, p. 172).

Near Bloemhof, Transvaal, Plowes (1946a, p. 142) found three
white eggs of the didric in as many nests of the masked weaver. That
he considered them all the product of one hen is indicated in his
conclusion that this cuckoo lays at least three eggs, ‘‘as I found that
number of white eggs in one Masked Weaver colony... .”” One further
instance of host specificity is that reported by Serle (1950, p. 356)
from British Cameroons. In a colony of black weavers, Ploceus
nigerrimus, four nests were parasitized by the didric cuckoo. The
four didric eggs involved were very similar, suggesting that they had

66 U.S. NATIONAL MUSEUM BULLETIN 265

probably all been laid by one bird which, by inference, was prone to
use this one species of fosterer.

To sum up, we have either no data at all (rujficollis, meyerir, flar-
gularis) or no usable data (maculatus, xanthorhynchus, cupreus) for
half of the species of glossy cuckoos. For the other six species for
which some (still uneven and at best meager), information is available,
the only currently permissible interpretation informs us that in all
species there seem to be some individuals that are not host specific
and others that are host specific, and that in some areas all of the
individuals have the same host choice, making for a local situation
of specific-host specificity. This last statement is true for geographic
segments of malayanus and lucidus, and almost so, in some areas, for
osculans. As far as the current observational records permit of inter-
pretation, individual host specificity is found together with individual
nonhost specificity, in parts of the populations of malayanus, lucidus,
osculans, klaas, and caprius.

This is a rather surprising state of affairs. From the standpoint of
the reproductive biology of avian brood parasites, the matter of host
specificity would seem to be an important, almost a basic, character-
istic, explainable as a result of a prolonged adaptive process under
the influence of natural selection. To find that it issubject to geographic,
subspecific, and even individual variation shows otherwise. In some
parasites, such as the European cuckoo, practically all the individual
hens are host specific; in others, such as the brown-headed cowbird
the great majority are nonspecific, but in the glossy cuckoos we find
all stages within each of several species! Lest the novelty of this
situation seem unique, however, one may recall that a similar diversity
in another aspect of their total behavior exists in many birds, including
some of the glossy cuckoos, namely in their migratory habits, where
the same species may have highly migratory as well as completely
sedentary races and, as in the case of the song sparrow, migratory
and sedentary sympatric individuals.

Egg morphism

Inasmuch as adaptive resemblance between the egg shells of brood
parasites and those of their regular hosts is very marked in some
instances and inasmuch as this is one of the more obvious areas in
which evolutionary adaptation to a parasitic mode of reproduction
may be expressed, it is essential that we review the situation—and
the evidence behind it—in the various species of glossy cuckoos.
Fortunately, the coloration and dimensions of the egg shells are
known for 9 of the 12 species, even though our knowledge of some of
them is less ample than we might like.

AVIAN GENUS CHRYSOCOCCYX 67

The characteristics of the egg shells, coloration, size, gloss, and
porosity, etc., are not necessarily simple to explain in an adaptive-
evolutionary sense, since they may have come about in more ways
than one. Furthermore, egg shells of brood parasites seem to be
unusually subject to natural selection and consequently are relatively
unreliable indications of past events or of interspecific relations.
Thus, one species of parasite may have begun with an originally
broad range of egg variability and later may have developed special-
ized egg morphs, uniform for each individual hen and each specific
on a single species of fosterer, while another may have begun with a
constant, or only narrowly variable, egg pattern. In the latter case,
the parasite may have remained with a single egg type and may have
come to select hosts with fairly similar eggs, or it may have developed
a broader range of coloration than it had originally. Unfortunately,
in no case can we claim to know with any finality which course was
followed. All that we can do is to describe the present situation in
each of the nine species and see if there are any clues or suggestions
as to trends, past conditions, or appreciable, inferential, evolutionary
changes in them, and, in addition, to see if together they yield any
hints of their history as a group.

In our attempted reconstruction of the phylogeny of the species
of the genus Chrysococcyr we have already seen that the African
members of the group are markedly different from the Asian and
Australian ones. The gap, both in morphological characters and in
geographic distribution, that separates them from their eastern
relatives is the largest void in the phylogenetic picture. It is pertinent
at this time to point out that there is a correspondingly great differ-
ence in their eggshell characters as well. The eggs of three of the four
African species (caprius, cupreus, and klaas, the eggs of flavigularis
being unknown as yet) are far more variable within each species—
actually polymorphic—than are the known eggs of the southern
Asiatic and the Australasian species (basalis, lucidus, maculatus,
malayanus, osculans, and xanthorhynchus). Some of the latter, of
whose eggs sufficient numbers are known to give a trustworthy
picture, are remarkably uniform, as, for example, basalis, lucidus, and
osculans. This seems to be the case, although with less supporting
evidence (smaller yet sufficient numbers of eggs) in malayanus, but
not in maculatus and xanthorhynchus.

The degree of variability of the eggs, chiefly in their coloration,
ranging from a monomorphic to a polymorphic condition, is not ob-
viously related to, or correlated with, the diversity and the number
of kinds of hosts used regularly. Thus, the species of glossy cuckoos
with very extensive lists of hosts include basalis and lucidus—each

68 U.S. NATIONAL MUSEUM BULLETIN 265

with practically monomorphic eggs—and caprius, cupreus, and klaas—
each with polymorphic eggs. On the other hand, osculans, with a
single egg type, uses only a few species of fosterers, and its eggs agree
quite closely with those of its most favored host, Chthonicola sagittata.
It is to be remembered that even those species of cuckoos with ex-
tensive lists of known hosts tend to parasitize only a fraction of them
with any great regularity.

The basic fact of polymorphism, regardless of whether it applies
to eggshell characters or to any other phenotypic aspect of a species,
would appear to be adaptive or at least would make adaptive evo-
lution more readily possible. In the case of brood parasites, eggshell
adaptation is of particular importance, but even here the resulting
situation is not necessarily simple to interpret. Thus, it is obvious
that a species of cuckoo with a single egg type, but using a wide
variety of fosterers, would inevitably come up against some whose
eges its own approximated fairly closely and others whose eggs were
widely dissimilar. In some cases, where enough data are available to
establish the correlation between acceptance or rejection of parasitic
eges by fosterers and the degree of egg similarity, it is clear that such
resemblance does confer a significant biological advantage on the
parasite. Examples of this are the “gentes” of the European cuckoo,
Cuculus canorus, and the Indian breeding population of the jacobin
crested cuckoo, Clamator jacobinus. Strangely enough, however, in
other cases lack of egg resemblance does not always appear to mitigate
critically against the parasites, as in the case of the jacobin cuckoos
breeding in southern Africa (Friedmann, 1964, pp. 20, 21).

It follows from the above that, before we may go more deeply
into the problems related to egg adaptation and egg morphism, it is
necessary to present the data for each of the nine species of glossy
cuckoos with all pertinent details.

1. C. malayanus: eggs are known of five of the subspecies of this
glossy cuckoo; in all cases they can best be described as monomorphic
with fairly narrow variational limits. In typical malayanus the egg
is dark olive-green with some small brown specks forming a wreath of
darkish brown. Schénwetter (1964, p. 570) noted that such coloration
is the forerunner of the development of the surprising bronze tone
found only in the eggs of some glossy cuckoos and of some species of
the related genus Cacomantis. In C. m. malayanus the egg color is
not adapted to that of its hosts’ eggs as far as the still meager data
permit a generalization. In C. m. albifrons, Bartels (1925) found the
ege to be bronze colored (ex nest of Gerygone sulphurea). In C. m.
poecilurus, Schénwetter described the eggs as uniform yellowish olive-
brown or greenish olive-brown, somewhat darker, more bronze than
in C. lucidus plagosus. In C. m. russatus the egg varies from pale to

AVIAN GENUS CHRYSOCOCCYX 69

dark olive-brown, slightly freckled with dark brown; in some the
dark color may be accentuated at the two ends of the egg, forming
indistinct bands. North (1912) merely described the eggs as dark
bronze with an olive or chocolate tone, with a few flecks at the obtuse
end. In C. m. minutillus the eggs are uniformly greenish olive or dark
bronze, like those of C. m. poecilurus.

Measurements (in mm.) are given as follows by Schénwetter (1964,
p. 587): C. m. malayanus: length 18; width 12.8; weight of full egg
1.5 grams. C. m. poecilurus: length 19.6 (19.0-20.2); width 13.7
(13.3-14.7) ; weight of empty shell 0.12 grams; thickness of shell 0.08;
weight of full egg 2.0 grams; relative weight of shell to that of full
ege 6 percent. C. m. russatus: length 20.3 (19.8-21.0); width 1.36
(13.4-14.0); weight of full egg 2.02 grams. C. m. minutillus: length
18.9 (18.5-19.3); width 13.7 (13.2-14.2); weight of full egg 1.85
grams.

2. C. lucidus: eggs monomorphic with some variation in the overall
tone, especially in the nominate race. Because the eggs of two races
(lucidus and plagosus) present slight differences, this general statement
needs to be amplified. In typical ducidus the eggs seen by most ob-
servers or authors (North, 1912) are uniformly olive-brown with a
somewhat bronze tone. However, years earlier Buller (1888) described
them as usually greenish-white to pale olive washed with brownish
gray. This is probably the reason why Oliver (1955, pp. 533-536)
wrote that the eggs of lucidus are greenish or bluish white to olive-
brown or dark greenish-brown. In the Australian race, plagosus, the
eggs are also uniform, varying from yellowish olive-brown to greenish
olive-brown (like bronze) but sometimes with a more grayish tone.
Serventy and Whitell (1962, p. 269) wrote that the bronze-olive pig-
ment is soluble in water, leaving the washed egg light bluish. This
explains Oliver’s description, and also recalls the similarly removable
part of the reddish-brown pigment in the eggs of C. osculans.

In the case of plagosus there is little or no egg resemblance to the
eggs of the numerous hosts, but since many (though not all) of the
hosts build domed or globular nests, the lower level of the internal
illumination there may help to compensate for the lack of similarity.

Schénwetter (1964, p. 587) gives the following measurements (in
mm.) for the eggs of the two races of C. lucidus: length 18.3 (17.2-
19.4) in plagosus, 18.9 (18.0-20.3) in lucidus; width 12.9 (12.0-14.2)
in plagosus, 13.1 (12.5-15.2) in ducidus; weight of empty shell 0.095
grams in plagosus, 0.10 grams in lucidus; thickness of shell 0.065 in
plagosus, 0.06 in lucidus; weight of the full egg 1.66 grams in plagosus,
1.73 grams in lucidus; percentage of weight of empty shell to that of
full ege 5.7 percent in plagosus, 5.8 percent in lucidus.

3. C. basalis: egg apparently monomorphic, white, minutely

70 U.S. NATIONAL MUSEUM BULLETIN 265

speckled and blotched with pinkish red; in some cases, described by
Schénwetter (1964, p. 569), the spots are less pinkish and more olive-
brown. The texture of the egg is smooth, the pores indistinct. In
Schénwetter’s table we find the following dimensions (in mm.):
length 18.1 (16.9-19.0); width 12.7 (11.9-13.3); weight of empty
shell 0.09 grams (0.08-0.11); thickness of shell 0.06; weight of full
egg 1.55 grams; relative weight of shell to that of full egg 5.8 percent.

The eggs of this cuckoo show some resemblance to those of some
of its hosts, especially of the genera Malurus, Ephthianura, Neositta,
Stipiturus, Gerygone, and Petroica, and little or no resemblance to
others, such as Rhipidura, Sericornis, Smicrorms, Cisticola, Chthoni-
cola, Calamanthus, Meliornis, Zosterops, Aegintha, and Taeniopygia.

4, C.osculans: monomorphic; elliptical or compressed-oval in shape,
uniformly dark reddish-brown or chocolate-brown, very similar both
in coloration and in size to the eggs of the most favored host, the
speckled warbler, Chthonicola sagittata, also agreeing fairly closely
with those of one of its few other fosterers, the red throat, Pyrrholaemus
brunneus, but not similar in color to those of other irregularly used
hosts, the yellow-tailed thornbill, Acanthiza chrysorrhoa, and the
Mallee heath wren, Hylacola cauta. That these latter species all make
domed or globular nests with dim internal visibility may help to offset
the lack of similarity between their eggs and those of the parasite.
According to Chisholm (1935, p. 70) the pigment on the shells of
osculans eggs is, at least partly, very superficial, as some of the reddish-
brown color rubs off on moist fingers. The eggs of osculans are very
different from those of any of the other glossy cuckoos in their rich,
dark color. The nearest to them are the eggs of lucidus and malayanus,
which are unmarked, bronze or olive; those of the others are very
different, light-colored, and show varying degrees of freckling and
spotting. For its body size, osculans lays a smaller egg than any of its
congeners, 19-22 & 14-15 mm. (ex Serventy and Whitell, 1962, p. 268),
possibly an adaptation to its highly restricted parasitism on a very
few host species. Schénwetter (1964, p. 586) gives the following
measurements (in mm.) for osculans eggs: length 21.1; width 15.5;
weight of full egg 2.75 grams.

5. C. maculatus: present data, chiefly ex Baker (1942, p. 80) and
Schénwetter (1964, p. 568) hardly more than suggests that the eggs
of this cuckoo are polymorphic. It is difficult from the descriptions,
which are all I have to rely on, to state whether there are two or more
fairly distinct types or one variable, but not readily divisible, one;
eggs are whitish, usually with a yellowish tinge and sometimes a slight
pinkish one, and with numerous pale brown-red flecks which are most
frequent at the obtuse end of the egg, generally similar to the eggs of
some of the sunbird hosts, such as Aethopyga svparaja seherrae. Eggs

AVIAN GENUS CHRYSOCOCCYX Gk

taken from nests of Arachnothera longirostris show a wreath of small
spots of brown, less reddish than those of the host. Another egg, also
attributed to this cuckoo, is so densely marked with brown and gray
as to be unusually dark in color. The eggs of this cuckoo are short,
broad, and oval to elliptical in shape, the pores fairly coarse for so
small an egg. The eggs are very thin shelled for a cuckoo (the weight
of the shell only 5.1 percent of that of the full egg, as compared with
7.4 percent in C. caprius), only slightly thicker than the eggs of the
sunbirds. Baker (1942, p. 203) gives the dimensions of the eggs of this
cuckoo as averaging 16.9 X 12.3 mm., the maximal ones being 18.0
12.6 and 16.3 X 12.8 mm., the minimal ones 15.1 X 12.0 and 15.9 x
11.2 mm. Schénwetter’s figures give a range of 15.4-18.5 & 12.0-12.9
mm., but in his table (p. 587) gives the following measurements (in
mm.): length 16.9; width 12.3; weight of empty shell 0.07 grams;
thickness of shell 0.05; weight of full egg 1.37 grams; relative weight
of egg shell to that of full egg 5.1 percent.

It should be mentioned that there is still some uncertainty about
the variational limits of the eggs of C. maculatus and C. xanthorhynchus.
Baker (1942, p. 80), who had seen more of each than anyone else,
admitted that the eggs of the two ‘‘are not individually distinguish-
able... ,” yet he described an egg type of C. xanthorhynchus which
seems quite different from any he mentioned of C. maculatus (see our
description of C. zanthorhynchus for further data).

6. C. xzanthorhynchus: said by Baker (1942) and by Schénwetter
(1964, p. 569) to be similar in their size and color variations to those
of C. maculatus; white, tinged with yellow, or pinkish, and flecked in
various tones of brown and reddish, achieving a fair resemblance to
the eggs of the hosts Arachnothera longirostris and Aethopyga siparaja
seheriae and only moderately similar to those of other hosts of the
genera Dicaeum, Cisticola, Orthotomus, Trichastoma, Alcippe, and
Napothera. In the case of eggs laid in nests of the little spider hunter,
Arachnothera, Baker (1942, p. 80) wrote that “‘an egg has been evolved
which agrees wonderfully well with those of the Spider-Hunter, some
indeed of the eggs of the Violet Cuckoo have to be weighed before
identification can be accepted. These eggs are pinkish, nearly always
pale, with a ring of reddish spots around the larger end, well defined
in both the Cuckoos’ and the Spider-Hunters’ eggs . . . Eggs inter-
mediate between the two types simulating Sunbirds and Spider-
Hunters are also to be found and are in most cases accepted . . <
It should be clarified that Baker was writing about eggs of both
zanthorhynchus and maculatus in this sentence, the eggs simulating
those of the sunbirds being maculatus. In Burma, Smythies (1953)
found zxanthorhynchus eggs to vary from pure white to pink in their
ground color, with a wreath of reddish flecks at the larger end.

ie U.S. NATIONAL MUSEUM BULLETIN 265

Baker gives the dimensions of nine eggs of the violet cuckoo as
averaging 17.31 X 12.25 mm., the largest eggs measuring 17.9 X 12.0,
and 16.1 X 13.3, the smallest ones 15.8 X 12.6, and 16.2 X 11.2 mm.
Schénwetter’s figures are as follows: length 17.2 mm.; width 12.5 mm.,
weight of full egg 1.40 grams.

All known eggs of the violet cuckoo are of the nominate race.

7. C. klaas: eggs polymorphic, seven main types, plus variations
that do not agree closely with any of them. The main types are:
1. white with numerous flecks of Indian red (oviduct egg, taken by
Lynes, 1934, p. 56). 2. cream-colored flecked over all with grayish and
brownish (‘‘Passer” type of Schénwetter, 1964, p. 567). 3. pale blue
with round speckles of reddish-brown and violet (found in nests of
Chalcomitra, Prinia, and Cisticola); also one oviduct egg reported by
Chapin (1939, p. 201). 4. pale green, with a loosely formed ring of
dusky, narrow markings found in a nest of a sunbird, Chalcomira
senegalensis. 5. light, buffy chestnut or creamy chestnut with markings
of pale, but bright, chestnut, found in nests of Prinia subflava (Pitman,
1957, pp. 3-6). In this instance it is worth noting that at Broken Hull,
Zambia, Pitman examined 100 nests of the Prinia and found
7 of them to contain eggs of klaas. The cuckoos’ eggs were all of
one type: “bluntly ovato and a handsome light buffy chestnut on a
creamy chestnut with pale markings of bright chestnut - . . . In
no instance does the cuckoo’s egg mimic the wavy markings, scrawls
and strageling hair lines of this Prinia; otherwise they can be con-
sidered an excellent imitation of many of the rufous buff and buffy
chestnut eggs of Prinia. This suggests a possible preponderance of
rufous buffy eggs of Prinia, or rather that this variety of egg is pre-
dominant, which, however, is not the case. . . .” The Prinia eggs
are very variable, and Pitman found no apparent preference by Klaas’s
cuckoo for any one type, ‘though it is interesting that the blue type
appears to be avoided. . . .” 6. pinkish white, heavily spotted with
darker pink, all in nests of Batis capensis. (MacLeod and Hallack
[1956, pp. 2-5]). 7. uniform, dark chocolate-brown, recorded so far as
I know only by Pitman (1957, pp. 3-6) from a nest of Anthreptes
collaris, at Malindi on the Kenya coast. This egg phenotype is of
particular interest in that it reflects (or appears to reflect) the con-
dition found in osculans and, to a lesser extent, in lucidus and in
malayanus.

Variants, apparently fairly close to type 4, taken in Uganda, have
been described as greenish-white speckled with brown and slate; others
nearer to our type 3 have been reported as verditer blue spotted with
red-brown.

Pitman’s observations on the lack of precise, adaptive host-egg
similarity in klaas eggs laid in Prinia nests are further corroborated

AVIAN GENUS CHRYSOCOCCYX 73

by those of others dealing with still different hosts. Thus, a record by
Bell-Marley (in Friedmann, 1949a, p. 136) involving the amethyst
sunbird and another by Roberts (1940, p. 143) concerning a parasitized
nest of the paradise flycatcher showed similar discrepancy in appear-
ance of the eggs of the parasite and of its hosts. On the other hand,
Pitman himself (1957, pp. 3-6) wrote that at Entebbe, Uganda, the
sunbirds, Neciarinia erythroceria and Chalcomitra senegalensis, were
common hosts. “The eggs of both . . . species are generally dark
brownish in appearance, and the eggs of C. klaas are likewise. . . .”’
Again, Pitman (in litt.) summarized much of his experience with eggs
of klaas in Uganda by describing them as resembling to a fair degree
the eggs of some of the commonly used hosts, particularly in their
densely speckled pattern.

The eggs of klaas are much like those of caprius in their variable
color patterns but are smaller in size and, in general, somewhat more
slender. According to Pitman, the eggs of klaas are ‘tougher’ than
those of either caprius or cupreus. Eggs of klaas vary in size from 15.2
to 19.5 mm. in length and from 11.4 to 12.6 mm. in width. The larger
measurements in my earlier account (1949a, p. 137) now appear to
have been of caprius eggs misidentified as klaas in the literature.

Egg measurements (in mm.) given by Schénwetter (1964, p. 586)
are as follows: length 18.9 (16.9-20.0); width 12.8 (12.1-13.5) ; weight
of empty shell 0.10 (0.08-0.11) grams; thickness of the shell 0.07;
weight of full egg 1.65 grams; relative weight of shell to weight of full
egg 6.1 percent.

The known eggs of klaas are all of the nominate race.

8. C. cupreus: apparently polymorphic, but only a small number of
eggs are known; these may be divided into four types: 1. white, either
immaculate or with a few purplish flecks forming a loose wreath at
the obtuse pole. 2. white or cream, very thickly speckled with olive-
brown, found in nests of olive sunbird by Benson & Benson (1947,
p. 4) in Nyasaland and by Moreau in Tanzania; this egg type agrees
fairly well with those of the host. 3. pale pinkish to pinkish white,
spotted with brown and gray, “similar to those of Pycnonotus, but
smaller...’ (van Someren, 1956, p. 159); found in nests of the bulbul,
Pycnonotus barbatus, in Kenya. 4. pale blue (in collections, faded
afterward to white), described by Schénwetter (1964, p. 568).

In spite of the meager quantity of evidence, there is reason for
interpreting as “probable” some adaptation in egg coloration to at
least two hosts, the yellow-vented bulbul, Pycnopotus barbatus, and
the olive sunbird, Chalcomitra olivacea. The eggs of the parasite are
smaller than those of the bulbul, but larger than those of the sunbird.
The bulbul is the most frequently recorded host of the emerald

74 U.S. NATIONAL MUSEUM BULLETIN 265

cuckoo (9 instances out of a total of 62 cases of parasitism involving,
in all, some 41 species and subspecies of hosts).

The measurements given in my earlier account (1949a, p. 121) were
based on two doubtful examples (ez nests of Colius and Amblyospiza)
and are too large. One egg, subsequently measured, was 20.5 & 13
mm. Schénwetter (1964, p. 587) gives the following size data (in mm.):
length 17.8; width 12.2; weight of the empty shell 0.06 grams; thick-
ness of shell 0.04 mm.; weight of the full egg 1.43 grams; relative
weight of shell to that of full egg 4.2 percent.

There appear to be no differences between the eggs of the subspecies
of C. cupreus (eggs of intermedius and of sharper known).

9. OC. caprius: eggs polymorphic, five main types plus some variations
that do not agree very closely with any of these. The main morphs are:
1. unmarked white, stated by Schénwetter (ed. Meise, 1964, p. 567) to
be rare, but also reported by Priest (1948, pp. 47-48) and by Moreau
(1949, p. 535); recorded from nests of Parisoma subcaeruleum and
Ploceus velatus, Ploceus intermedius, Ploceus ocularis, and Euplectes
oriz (Ottow and Duve, 1965, p. 435). 2. uniformly greenish-blue, a
common type frequently found in nests of Huplectes oriz, the eggs of
which host are similar in color but usually smaller in size. In the
Transvaal R. A. Reed (in ltt.) informed me that all caprius eggs he
found in nests of the red bishop (EZ. orix) were “‘quite indistinguishable
from those of the host, being a plain deep blue and of the same size
and shape as those of the host. . . .”” Again, G. Duve (in litt.), also
in the Transvaal, found only blue eggs of caprius with Huplectes oriz,
no blue eggs of the parasite in the nests of the other common local
host, Ploceus velatus, with which only speckled cuckoo eggs were
found. A plain, blue caprius egg is known from a nest of the black-
chested Prinia, P. flavicans, found close to a nesting colony of Huplec-
tes orix. It is possible that this egg was deposited by a didric otherwise
parasitic on the red bishops nearby. Ottow and Duve (1965) distin-
guish two types of unmarked blue eggs, a pale type which Duve found
in 3 nests of Ploceus capensis and in 7 of Huplectes oriz near Johannes-
burg, and a darker type found by Duve in 13 nests of Huplectex orix
in the same area. 3. Pale green or cloudy white, sparsely splashed with
grayish and with grayish brown (referred to by Schénwetter as the
Ploceus velatus type), found with similarly colored eggs of Ploceus
velatus but also with whitish eggs of Ploceus intermedius cabanisi,
and with greenish-blue eges of Ploceus capensis olivaceus. This is a
frequent egg morph of the didric cuckoo. Chapin (1939, p. 179) obtained
an oviduct egg of this type. 4. Background color varying from dull
white to fairly bright pale-green, blotched and speckled with coarse,
heavy, and, in some instances, dark-brown and grayish markings. This
type has been reported from nests of Passer melanurus, whose eggs

AVIAN GENUS CHRYSOCOCCYX 75

generally are fairly similar, but also from nests of Euplectes oriz and of
Ploceus capensis olivaceus, both of whose eggs are uniformly bluish,
and from nests of Ploceus velatus and Ploceus xanthops gamesont, both
of which species lay speckled eggs. According to Schénwetter this is
the most frequent type of caprius egg (10 out of 24 that he examined).
Near Johannesburg, R. A. Reed (in litt.) found that all caprius eggs
found in nests of Passer melanurus were lighter in color than those of
the host, with some tinge of blue in the whitish ground color and with
freckling, in every egg examined, finer and more evenly spread, al-
though the freckling was heaviest around the obtuse pole of the eggs.

Roberts (1926, pp. 232-234) described a number of didric eggs of
this morph, comparing them with those of the hosts in whose nests
they were found, reported a fair approximation between them in four
clutches of Passer melanurus. In other cases, however, there was little
or no egg similarity, as was further shown by Plowes (1945, p. 113),
who noted no less than four different didric egg morphs in nests of
Ploceus velatus alone, none of them agreeing with the eggs of the host.
5. Pinkish background color, with speckles and larger markings of
pinkish brown, and brownish gray (not listed by Schénwetter, but
recorded from a nest of Ploceus velatus by R. A. Reed [in litt.]; appar-
ently a relatively uncommon egg morph). The egg described by
Markus (1961, p. 33) was merely described as light pink speckled with
pinkish brown; the one reported by Reed had a pinkish ground color,
with dark frecklings of browns and grays sparsely scattered, except
on the obtuse end where these markings coalesced to form a ring.

Other, somewhat variant, egg morphs have been described, as
follows: cream color, finely blotched with light reddish brown and
underlying pale mauve; very pale green with reddish-brown blotches,
especially near the larger pole; blue with greenish spots (Markus,
Priest, and others).

Judging from the data presented above, together with further
notes by Hunter (1961, p. 55), Markus (1963, p. 47; 1964, p. 128),
Moreau (1949, pp. 535-536), Reed (1953, p. 138), and others, and
from the conclusions of Schénwetter (1964) it may be said that the
didric cuckoo shows adaptive egg resemblance in coloration to two of
its common hosts, Euplectes oriz, and Passer melanurus, but that this
is by no means constant. The degree of adaptation or, perhaps more
accurately, the incidence of approximate resemblance is greater in
those individual didrics parasitic on red bishops than in those laying
eggs in the nests of Cape sparrows. In the case of those didrics para-
sitizing masked weavers there is less evidence for constant egg adapta-
tion. Markus (1961, p. 33) found three types of didric eggs in nests
of this host. Hunter (1961) studied about 120 nests of the masked
weaver and distinguished 10 egg morphs of this species. He found

76 U.S. NATIONAL MUSEUM BULLETIN 265

that in the parasitized nests (12, or 10 percent of the total) the didric
eggs more often resembled one of these color morphs, less often those
of two other types.

Since the egg pattern of the masked weaver is so variable as to
permit the designation of 10 recognizable types, it is obvious that
it would be very difficult, if not quite improbable, for a parasite’s
ege to have evolved any great degree of resemblance. Yet, it seems
that some adaptive evolution has transpired and is going on, but in so
unclear and complicated a situation that it is not possible to measure
or to define it. The colored illustrations given by Ottow and Duve
(1965, pl. 1, figs. a and b) of two very different sets of eggs of Ploceus
velatus, each with an egg of caprius, show a marked resemblance
between parasite and host. These are extreme instances of positive
ege simuarity with this favorite, but ovopolymorphic host. In other
cases the eggs of the two show no such close agreement. Duve’s own
records reveal that four of the egg morphs of caprius were found in
nests of Huplectes oriz, a host that lays unmarked bluish eggs only,
with which only two of the parasitic egg types correspond. Yet, so
experienced an oologist as Pitman (MS., 1965) considered that the
didric cuckoo’s eggs have become adapted to at least half a dozen
species of hosts. The evidence for this conclusion is unknown to me;
when Pitman’s work is published this point will be of much interest.

Of the large number of species of hosts (67) recorded in this report
for the didric, with a total of 426 instances of parasitism, the three
most frequent fosterers are the red bishop, Hwplectes orix, with 77 cases,
the masked weaver, Ploceus velatus, with 105 instances, and the Cape
sparrow, Passer melanurus, with 43 records. It is, perhaps, due to the
polymorphic nature of the masked weaver’s eggs that only individual,
but not invariable, egg resemblance is to be found with them, while
with the other two fosterers the egg adaptation of the didric is quite
readily discernible, even if not highly perfected with regard to the
Cape sparrow.

There is also some evidence for adaptive resemblance of egg size
in the didric. Pitman (MS., 1965) reported that seven didric eggs taken
from nests of Ploceus cucullatus and Ploceus nigerrimus measured 22.2
X 15 (20.4-23.3 & 14-16 mm.), while nine others from nests of smaller
species of Ploceus with correspondingly smaller eggs, Ploceus inter-
medius and Ploceus pelzelni, measured 19.9 X 138.7 (18-21.4 X 13-
14.7 mm.). For ready comparison the egg sizes of the hosts involved
may be stated:

Ploceus cucullatus: 21.7-25.7 * 14.9-16.5 mm.

Ploceus nigerrimus: 22-26.2 * 15.4-17 mm.

Ploceus intermedius: 20-23.6 13.8-15.4 mm.

Ploceus pelzelni: 18-19.5 % 13-19 mm. (all, ex Chapin 1954,
pp. 316, 338, 358-363, 367).

AVIAN GENUS CHRYSOCOCCYX idk

There is a close agreement in size between didric eggs (average 21.7
X 14.9) and those of the red bishop (average 20.5 & 14) and of Cape
sparrow (average 19 X 14 mm.). However, not infrequently the cuckoo
eggs are larger than even these host eggs in the same nest. Thus,
Markus (1964, p. 123) found a large didric ege, 25 14.5 mm., in
a red bishop’s nest and another measuring 23.7 14.3 mm. in another
nest of the same species.

The eggs of the didric cuckoo vary in length from 21 to 25 mm. and
in width from 13.8 to 17 mm.; the largest ones seen by me or recorded
in the literature were 24.8 X 16.5; 24.3 X 17; 25 X 15.5 mm.; the
smallest ones were 20.8 & 14.2; 21.1 & 14.5; 21.2 & 14.3 mm. Didric
cuckoo egg measurements tabulated by Schénwetter (1964, pp. 536,
586) are as follows: length 21.5 mm.; width 14.8 mm.; weight of the
empty shell .19 grams; thickness of the shell 0.095 mm.; weight of the
full egg 2.55 grams; relative weight of the shell to that of the full egg
7.4 percent; body weight of the bird 40 grams; relative weight of full
egg to body weight of the hen 6.4 percent.

To sum up the foregoing data, we may note that egg monomorphism
is characteristic of those species of Chrysococcyz found in the Australa-
sian portion of the range of the group, which are also, at least in the
present reconstruction of their history, nearer to the older stock of the
genus—malayanus, lucidus, basalis, and osculans. In the two Asiatic
species, maculatus and xanthorhynchus, the still meager evidence sug-
gests polymorphism, while in the three African ‘climax’ species,
caprius, cupreus, and klaas, the eggs are definitely polymorphic.

In the monomorphic egg-laying species the following specific
differences should be noted. In the case of malayanus there appears to
be some slight geographic, subspecific variation in egg coloration, but
not much within each racial entity, merely the range of color implied
in such descriptions as ‘‘yellowish olive-brown to greenish olive brown,”
or “sometimes slightly freckled.” In lucidus and in osculans there is an
easily rubbed off, superficial pigment, but the adaptive value of this
color is not dependent on its durability or removability; in fact in
lucidus there is no evidence that it is host-egg adapted before or after
alteration, while in osculans it is highly adapted to its main host prior
to any color loss and such loss occurs, if at all, after the critical period
of acceptance or rejection by the host is past. Such discoloration
probably occurs, although seldom in nests undisturbed by man, as the
eges must be rubbed to produce it. In basalis some degree of resem-
blance exists to the eggs of some of its hosts but not to those of others.

In the polymorphic egg producers of India, maculatus and
ranthorhynchus, we find a range of host-egg similarity from very close
to only fair or moderate. Coming to the African species, klaas shows
no egg resemblance to those of many of its hosts and not more than

267-562—68——7

78 U.S. NATIONAL MUSEUM BULLETIN 265.

a ‘fair’? degree to others; cupreus, with a systematically very diverse
group of hosts, gives evidence of probable egg adaptation toward
two hosts, a bulbul, Pycnonotus barbatus, and an olive sunbird,
Chalcomitra olivacea, the very disparity of which makes one wonder if
the present ‘probability’ is not merely a matter of coincidence in
fairly small samples and not really a statistically significant adapta-
tion. Finally in caprius there is some evidence for host-egg similarity
for two of its frequent fosterers, the red bishop Euplectes orix and
the Cape sparrow, Passer melanurus, some, but not constant, for its
other most frequent fosterer, the masked weaver, Ploceus velatus,
and no convincing adaptation toward its numerous other, less-used
hosts. Interestingly, the caprius eggs seemingly adapted to the Cape
sparrow, Passer melanurus, have been reported so far only from
southern Africa, in the range of that host species. This makes it
appear like a real adaptation; if it occurred as well in more equatorial
regions where this particular host is absent, it might seem that it
was a widespread phenotype that happened to be suitable in southern
Africa to the Cape sparrow.

Egg adaptation occurs to a well-developed degree in the Australian
species, osculans, to a lesser degree in basalis, in the two Indian
species, maculatus and xanthorhynchus—but only with some of their
host species, and to a variable degree in three African species, caprius
(well-developed with two hosts, not with others), capreus (again only
for two of its hosts and not others), and to only a “fair” degree in
klaas with a few of its frequent hosts. The most perfect adaptations
are between C. osculans and its chief host Chthonicola sagittata,
between C. maculatus and Arachnothera longirostris, and between
C. caprius and Euplectes oriz and Passer melanurus.

There is, then, no well-defined, progressive path of adaptation;
it is more of a sporadic type of development in different sections of
the genus Chrysococcyz. In some instances it is possible to “explain”’
the lack of adaptive evolution, as in many instances of the parasitism
of C. caprius on Ploceus velatus, which host lays such a wide range of
egg phenotypes that it would be difficult for the parasite to come
under any steady, selective influence. Another instance is the frequency
with which OQ. lucidus plagosus parasitizes birds that build domed
or covered nests in which the poor illumination tends to minimize the
effect of visual differences between the eggs of the parasite and those
of the host.

In the case of the European cuckoo, Cuculus canorus, it is well
known that the egg is extremely small for the size of the bird, a little
over 3 percent of the body weight, while the egg of most self-breeding
birds is usually about 10 percent of the body weight. Whether the
small egg of O. canorus is the result of a progressive, adaptive reduc-

AVIAN GENUS CHRYSOCOCCYX 79

tion in egg size, permitting the bird to use hosts much smaller than
itself, is only conjectural, but the fact remains that the bird does use
chiefly small passerine species as fosterers. While the glossy cuckoos
do not exhibit such striking egg reduction, they do lay eggs that are
fairly small in relation to their body size, which may be of adaptive
value in approximating the size of the eggs of some of their frequent
hosts. For example, the body size of C. basalis is much greater than
that of the species of Malurus that it parasitizes, but the eggs of the
two are very similar in dimensions. Again, the egg of the African
yellow-bellied emerald cuckoo, C. cupreus, is surprisingly light in
weight, almost as light as eggs of the two much smaller Asiatic species,
C. maculatus and C. zanthorhynchus; the full egg weight is 1.43 grams
in cupreus, 1.37 grams in maculatus, and 1.40 grams in xzanthorhynchus,
whereas the dimensions of the eggs are 17.8—20.5X12.2-13 mm. in
cupreus and only 15.1-1811.2-13.3 mm. in the two Indian species.
The body size and weight of cwpreus exceed the figures for maculatus
and zanthorhynchus by approximately 40 percent. The eggs of these
two very small species of Chrysococcyx were compared by Burton (1935,
p. 276) with those of two Indian species of Cuculus, poliocephalus and
saturatus. His results emphasize the difference in extreme egg reduc-
tion in these species of Cuculus and in Chrysococcyz, as he was led to
write of the little Asiatic emerald cuckoo, C. maculatus, that its “eggs
are very large for cuckoo’s eggs, in proportion to the size of the bird,
the bulk being as much as it is in the eggs of poliocephalus . . . and
saturatus . . . birds of, perhaps, between three and four times the
cubic contents of the tiny Emerald Cuckoo.”

The largest and heaviest eggs of all the glossy cuckoos are those of
osculans and caprius. This is in agreement with their larger body size,
but if Schénwetter’s figures are correct, the egg weight in C. caprius
is 6.2 percent of the body weight, while in C. lucidus plagosus, a much
smaller egg and bird, the egg weight is 7.9 percent of the body weight.

Although in some cases there may be selective value in approximate
size agreement in the eggs of the parasite and of the host, this does
not always operate on a critical level. Thus, in New Zealand, the
little gray warbler, Gerygone igata, a bird that lays an egg about 18 X
12.5 mm., is parasitized by two very dissimilar cuckoos, the nominate
race of the bronze cuckoo, Chrysococcyx lucidus, which produces an egg
of very similar size, and the larger, very different, long-tailed cuckoo,
Urodynamis taitensis, that lays an egg about twice as long and twice
as broad (32 & 27 mm.).

The recent experimental work of Tinbergen (1951, p. 45; 1954, pp.
246-247) has shown that discrepancy in size does not deter an egg’s
acceptance by many birds. In fact, he found that the unusually great
size of some of the egg models used had the effect of increasing the

80 U.S. NATIONAL MUSEUM BULLETIN 265

observable, released incubatory response of the birds. In his experi-
ments the largest models used were too big for the bird to cover
with its body, but even this did not act as a deterrant. Within much
more reasonable dimensional discrepancies, the same effect seems to
apply to many hosts of brood parasites. In general, the eggs of brood
parasites are usually larger than those of their hosts, but this is not
always the case, as has already been mentioned in Chrysococcyr
basalis and its Malurus hosts.

In proportion to the body size of their producers, the eggs of parasitic
cuckoos are relatively small compared with the same ratio of egg to
body size in the host species. Heinroth (1922) found this ratio in
self-breeding passerine birds to vary from 8 to 14 percent with an
average of 11 percent. In seven species of parasitic cuckoos Sch6n-
wetter (1964, p. 535) found the ratio to range from a minimum of
3.2 percent in Cuculus canorus to a maximum of 7.9 percent in Chry-
sococcyx lucidus plagosus, with an average of 5.4 percent.

The genus Chrysococcyx represents one extreme development of
the family Cuculidae. Its included species are the smallest of all the
cuckoos and are parasitic wholly on fairly small species of hosts.
The glossy cuckoos do not have this “area” of hosts to themselves,
however, as some of the larger cuckoos (Cuculus, Urodynamis, Caco-
mantis, and others) also make use of these small fosterers. The need for
reduction in egg size in the species of Chrysococcyz has been less than
in the larger forms that share with them the nests of small passerine
victims.

The evolutionary significance of dissimilarities in different stages
of the life cycle of organisms is well known and is a matter of particu-
lar importance in brood parasites. As was pointed out in my study of
the crested cuckoos of the genus Clamator (1964, p. 29), brood para-
sites are subject to the impact of natural selection on two levels.
‘Whereas in the case of self-breeding birds the entire biology of the
species is a closely coordinated unit . . . on which selection may
operate, in the case of brood parasites there is cleavage resulting in
two fairly separate parts. The evolutionary climate ambient to the
ege and nestling stages is that of the host species and has relatively
minor connections with, and repercussions upon, the selective factors
surrounding the life of the adult parasite.”” From this point of view
it is of interest to note that the coloration of the eggs of the sympatric
and partly homoxenic plagosus and basalis is markedly different,
plain olive-bronze in the former and white spotted with pink in the
latter. The two species reveal far greater differences in their egg shells
than in their plumages.

Inasmuch as the available observational data fails to reveal any
reliable, measurable difference in the adaptive success or failure of

AVIAN GENUS CHRYSOCOCCYX 81

these very distinct egg types (in the relative frequency of their ac-
ceptance or rejection by the hosts), it is not possible to evaluate this,
the most striking distinction achieved by these two closely related
species. The degree to which both species use hosts that construct
domed or covered nests, with the consequent low level of illumination
surrounding the eggs, is one factor that obscures the evolutionary
value of the two diverse egg patterns. In the case of open nests this
factor would not be present, and since many eggs of both species are
deposited in such nests, the problem is open to further study. It is
hoped that it may be investigated by Australian ornithologists, and
the results should be of much interest.

Mode of Egg-laying by Adult Cuckoos

Mode of deposition

While egg deposition is undoubtedly accomplished by direct laying
into the host nests in the great majority of instances, no one has ever
reported an eye-witness account of it. This is not evidence against it;
it is merely the usual absence of direct observation that applies even
to our knowledge of nonparasitic birds that are much easier to watch.
At the same time, some writers have concluded that, when parasi-
tizing certain types of nests, especially the small, semipendant ones
of some of the sunbirds, the glossy cuckoos may have to place the eggs
in them with their bills after having first laid them on the ground
nearby. Baker (1942, esp. pp. 122-132) reviewed all the data known
to him concerning European and Indian cuckoos and concluded that
he could find no ‘evidence to prove or disprove the contention that
one of the methods adopted by Cuckoos to place her egg in the nests
is by carrying it in her beak to the place she has chosen for it. I think
it is fully proved that she would not use this method if she could lay
in the nest direct or could project it into it through the entrance,
while supporting herself on the nest, or a twig, or something else. It
does happen, however, that Cuckoos’ eggs are found in a great num-
ber of nests in which it would seem impossible to have pJaced them by
any other means than by the beak.

“Personally, I think it is highly probable that this method is very
frequently adopted... .”

This kind of assumption has been made in the literature for some
of the glossy cuckoos in Africa, Australia, and Asia, but in almost
all instances it is unsupported by actual observations. However, in
the case of two of the Australian species, C. malayanus russatus and
C. basalis, there are on record some pertinent observations for each.
Because of the great interest attached to them they may be repeated
here.

82 U.S. NATIONAL MUSEUM BULLETIN 265

In the case of C. malayanus russatus there are two records. Barnard
(1926, pp. 6-7) saw one of these cuckoos clinging to the side of a ‘‘nest
of Gerygone magnirostris. I was quite close to the bird at the time and
could not mistake its identity. I waited till it flew off, then examined
the nest and found two eggs of the Gerygone and a freckle laid egg of
the Cuckoo. . . .” The commentator (A. J. Campbell) added to
this that in answer fo a question, Barnard replied, ‘“The bird (L. [=C.]
russatus) when seen at the Gerygone’s nest was clinging to the material
with the head at the entrance, but not inside, the bird’s tail pointing
to the ground; therefore it was impossible for the cuckoo to have been
leaving the nest (7.e., laying in it). The assumption is therefore that
the egg was placed in the nest and not laid in it; also from the size of
the bird the nest would be considerably disturbed, if the bird had
entered to lay. The nest in question was not disarranged in any way.”

A second case was reported by Seaton (1962, p. 176), who saw one
of these cuckoos fly to the nest of a yellow-breasted sunbird, Cyrto-
stomus frenatus, “carrying an egg in its bill; it clung to the side of the
nest and, placing its head in the aperture, deposited the egg in the
nest chamber. I rushed to the nest and on examination found the egg,
which was still warm, coloured and freckled like the egg previously
deposited [in another earlier nest by this cuckoo].”” The sunbirds
returned to the nest, chattered a little, and then deserted it, starting
a new nest nearby shortly afterwards.

Many years ago Bennett (1879, p. 245) made an observation on the
narrow-billed bronze cuckoo, C. basalis, indicative of mandibular egg
placement. He had once shot a female basalis and found it had an egg
of its own species in its throat. This led him to suspect that the bird
was on its way to a host’s nest in which it would have deposited the
ege held in its mouth. Some time later he found a nest of Malurus
lamberti containing two eggs of its own. Wishing to get a complete
clutch, he left it untouched and returned a few days later. As he came
near he saw a female basalis clinging to the side of the nest with its
head thrust down into the entrance. His approach caused the cuckoo
to fly off, and he examined the nest and found it to contain three eggs
of the fairy wren and one of the cuckoo. He concluded “that the
cuckoo must have carried the egg in her mouth and then deposited
it in the nest, for it did not appear possible for the bird to get the
whole of its body into the nest; indeed so small was ae aperture that
I had to tear the nest open to oe aia the eggs...

Another instance of mandibular deposition by ee same species of
bronze cuckoo was reported by Selby (1946, p. 186), who found a
nest with two eggs of the red-capped robin, Petroica goodenovit, on the
ground. The robins were excitedly worrying a cuckoo ‘‘which was sitting
on the sand. Very shortly the Cuckoo rose, picked up its egg in its

AVIAN GENUS CHRYSOCOCCYX 83

bill, and placed it in the Robins’ nest—leaving the two Robin eggs as
they were. The Robins worried the Cuckoo the whole time, until it
disappeared, after which the hen returned to the nest as if nothing
untoward had happened. . . .”’ In this case the nest was on the
ground and able to withstand the weight of the parasite had it entered
to lay an egg.

_Another less conclusive instance of mandibular oviposition by
C. basalts may also be recalled. A. C. Allen (reported by Ross 1946,
pp. 246-247) saw one of these cuckoos on the ground with an egg in
its mouth. Two blue wrens, Malurus cyaneus, nesting nearby were
much excited by the presence of the parasite, ‘‘which soon flew to a
small scrub and perched on the side of a nest. It stayed there for
about a minute making convulsive movements with its body and
flapping its wings. It then flew to an adjacent sapling, but the egg
had disappeared and the bill was closed. Mr. Allen then examined
the nest and it contained two eggs of a Wren and a white egg liberally
speckled with small red spots showing that the intruder was a Horsfield
Bronze-Cuckoo (Chalcites basalis) ... .’’ In this instance the actual
insertion of the egg was not really observed, although the implication
of the account strongly suggested it.

Still another case, called to my attention by K. A. Hindwood, may
be mentioned. Len Harvey (1961, p. 3) saw a female basalis carry her
own egg in her bill to a blue fairy wren’s nest, and a few seconds later
the cuckoo flew off with one of the wren’s eggs in her bill. This was at
Invermay, near Ballarat, Victoria.

In Kenya and Uganda, Pitman (in litt.) concluded that C. klaas
probably also resorted to mandibular egg insertion into nests of some
of its sunbird hosts, although he did not have the good fortune to
observe such behavior. Others have made similar suggestions for
C. cupreus, although also without direct observations.

By now we have seen that there is sufficient evidence to establish
the conclusion that mandibular egg placement does occur. By virtue
of the behavioral pliability behind this fact, nests that would otherwise
be unavailable to the cuckoos are made accessible for their parasitism.
It does appear, however, that this is an occasional rather than a
regular mode of egg laying. By and large, there is little reason to
assume that natural selection would ordinarily favor the evolution of
such a habit as a regular pattern, as it would seem to be connected
with a poor host choice. A bird nest too small to accommodate the
body of the parasitic hen would usually prove inadequate to hold the
young cuckoo after the first week or 10 days of its nestling growth.
Even Baker (1942, pp. 122-132), who was inclined to believe in
mandibular oviposition in a nest too small or too insecurely suspended
to bear the weight of an adult hen Cuckoo, attempted to use as “proof”

84 U.S. NATIONAL MUSEUM BULLETIN 265

of this method of egg deposition the argument that such a nest cannot
even ‘bear the weight of the young Cuckoo when half grown and often
breaks down before it is half fledged. . . . It is equally certain that
the Cuckoo cannot enter so small] a nest. It is a very strange sight
when a young Cuckoo gets too large for its abode. At first the nest
itself expands and the young bird sits with its head out of the entrance
encased in a trellis-work of grass, etc., which gradually gets thinner
and thinner until it bursts and the cuckoo is thrown headlong to the
ground ... .’”’ Even if, as Baker suggests, the catapulted young
parasite is then fed on the ground by its foster-parents, it would
seem that in many instances the destruction of the nest would be
fatal to the nestling in it or that an altricial young prior to the fledging
stage would not survive long either out of, or deprived of the protection
of, the nest.

While mandibular egg deposition may thus seem to have slight
evolutionary value, nevertheless, that occasionally brood parasites do
resort to this behavior pattern is of interest since it evidences a degree
of psychobiological adaptiveness that is in itself quite remarkable.
This, in turn, makes one wonder if the habit may have started early
in cuculine history with more ordinary, less flimsy or insecure, or less
uncomfortably small types of host nests. It is conceivable that it
might have had a value, both immediate and in the long range of
natural selection, of being a more rapid method of egg deposition than
direct laying into the nest; it certainly could have been advantageous
to the parasite, especially in nests well guarded by their owners. Once
such a habit, or such an extension of it, had become part of the scope
of the innate behavior of the cuckoos, it could reappear from time to
time.

The glossy cuckoos usually lay but one egg in any one nest. While
there are records of two and even of three eggs of some of these cuckoos
in a single host nest, they are definitely exceptional. As is well docu-
mented, multiple eggs deposited in the same nest are extremely rare
in the European cuckoo, Cuculus canorus, but are quite frequent, in
fact usual, in some of the crested cuckoos of the genus Clamator. The
species of Chrysococcyx agree much more with Cuculus than with
Clamator in this aspect of their parasitism. The rarity of multiple
versus single eggs in individual nests is true of all the glossy cuckoos
of whose eggs enough is known. While the following figures relate
particularly to some of the African species on which I have more
extensive data, the picture is similar in the Australasian members of
the genus. In C. caprius my records show 231 host nests with a single
didric cuckoo egg in each, 12 nests with two each, and only 2 nests
holding three of the parasitic eggs apiece. In other words, out of a
total of 261 didric cuckoo eggs, 245 were “‘singles’”’ when laid, and 16

AVIAN GENUS CHRYSOCOCCYX 85

were ‘‘multiples” or ‘extra’ eggs. That there may be some slight local
or individual variation in this matter of multiple-egg laying is sug-
gested by the fact that of 12 nests with two didric eggs each, 4 were
found in central Natal (but over a period of seven years)—all in nests
of the Cape weaver, Ploceuws capensis olwaceus.

In the case of C. klaas the number of nest egg records is much
smaller, but it reveals that in each of 29 nests there was a single klaas
egg, and in 3 nests there were two such eggs apiece. Years ago H. L.
White (1915, p. 145) summarized his large number of records for three
Australian glossy cuckoos, basalis, lucidus (plagosus), and osculans,
and found that there was usually but one cuckoo egg in a nest. Occasion-
ally he found two lucidus or basalis eggs together and once even three
basalis eggs, but in these cases it is unknown if the multiple eggs were
laid by the same or by different hens. In the two Malaysian species
maculatus and zanthorhynchus, Baker’s data included only single eggs
per nest, 11 in the case of maculatus, 9 for zanthorhynchus.

In the instance White described where three basalis eggs were in
the same nest, they were actually buried at different levels in the nest
lining, so that this case was in effect, more comparable to three
separate nests than to one with multiple parasitism. Another instance
of three basalis eggs in a nest of Malurus cyancus, reported by Parsons
(1918, p. 145), also involved eggs buried under later nest lining, but
in this instance it was not specified if they were buried together or at
different times.

Interval between eggs

The interval between eggs is still a matter of some uncertainty. There
is in the literature a tendency to assume that the small cuckoos, such
as Chrysococcyz, lay at daily intervals in contrast to the larger Cuculus
which lays at intervals of 48 hours. For example, in discussing the two
Asiatic species maculatus and xanthorhynchus, Baker (1942, p. 168)
wrote that two of his correspondents, C. M. Inglis and A. M. Primrose,
believed that these cuckoos laid at intervals of 24 hours, but added
that, inasmuch as he had never taken any but single eggs of these
birds, he could neither prove nor disprove the suggestion. Untortunate-
ly, neither Inglis nor Primrose have recorded their observational data.

In the case of the African caprius we have better, although con-
flicting information. In my earlier account (1949a, pp. 161-162) I
stated that the interval between eggs seems to be one day, not two as
in Ouculus, and pointed out that the pertinent evidence was of two
kinds. ‘In the ovaries of breeding females that [ examined there was
less difference in the degree of collapse and disintegration of the dis-
charged follicles than in comparable material of Cuculus. This implies
a shorter interval between successive discharge follicles, which leads

86 U.S. NATIONAL MUSEUM BULLETIN 265

me to think the eggs may be laid at intervals of one day. More direct,
observational data are supplied by Pringle (Ostrich, 1946, pp. 368-
369) who noted a female didric (ostensibly, but not absolutely cer-
tainly, the same individual) returning to a Cape sparrow’s nest on
three successive days, and each day depositing an egg in the nest.”

Recently Ottow and Duve (1965, p. 433) have interpreted Duve’s
very intensive and important field observations to imply a much
longer interval between eggs—at least four days. This surprising con-
clusion was based on Duve’s conviction from his observations that
he was reasonably certain that only three or four female didrics were
in attendance as parasites on a colony of red bishops, Hwplectes oriz,
and that he had practically every nest under observation. From this
he assumed that, if, as he thought, these didrics parasitized only the
bishops (and they would have had to fly “considerable distances” to
lay in other nests of other colonies of the same host) and if they laid
at daily intervals, he would have expected at least three or four times
as many didric eggs as he found in his daily inspection of each nest
in the colony.

The weak points in Duve’s data are that his cuckoos were not
marked for easy individual sight identification, that he may have
failed to find some of the bishops’ nests, and that the cuckoos might
have made “considerable flights” to other host colonies or might have
laid some of their eggs in nearby nests of other species of birds. In
other words, the four day interval postulated is an interpretation and
not an established fact. At the same time, it should be stressed that
while Duve’s conclusions are at variance with Pringle’s observations
and with the results of an examination of the ovarian follicles, the
intensity and meticulousness of Duve’s field work make his work
worthy of serious consideration. It is to be hoped that further studies
along the same line may be made for the additional light they may
shed on this problem. In our present state of knowledge, I do not
think it likely that a four-day interval exists, but at the same time I
would not rule out, or ignore, Ottow and Duve’s interpretation.
Further substantiation in greater detail is needed to make it acceptable
because of the exceptional and unexpected length of this longer
interval.

Duve (both in litt. and in his joint paper with Ottow [1965]) has
attempted to coordinate a longer egg interval with the fledgling-
feeding tendency of the adult didric. This I think is unnecessary,
since the feeding of newly fledged didrics by adults of their own
species is apparently an occasional rather than a “routine” behavior
and as far as published observations indicate, is done mainly by the
males and not by the egg-producing females.

AVIAN GENUS CHRYSOCOCCYX 87

Number of eggs

The number of eggs laid by one glossy cuckoo in one breeding
season is another aspect of their breeding biology on which we still
need further information. There are no data, either direct or infer-
ential, on any of the Australasian species of these birds. In the case
of the African species, klaas, I noted (1949a, p. 137) that one dissected
hen had one nearly ripe egg in the oviduct and three much enlarged
yolks in the ovary, suggesting that at least four eggs would have been
laid by this bird. In the case of caprius, Plowes (1946b, p. 271) found
three white eggs of this cuckoo in a small colony of masked weaver
nests (Ploceus velatus) near Bloemhof, Transvaal, and concluded that,
since this is an uncommon egg morph of caprius, all were probably the
product of the same hen, which would thus have laid at least three
eggs. In another colony of masked weavers containing 37 nests, I
reported (1949a, pp. 158-159) that examination showed that 20 were
in use and that of these, 4 each contained one caprius egg. The eggs
were all alike in size, color, and markings and were probably all the
product of the same hen. In another case, a colony of 28 nests of the
same weaver, 3 contained one egg each of the didric, again all alike in
color, markings and size. In this case I collected the female didric
and “although the bird was badly spoiled by the shot, I could make
out with the aid of a hand lens that there were three discharged egg
follicles in the ovary. There might, however, have been more but I
could not make out any others definitely. . . .”” Ottow and Duve
(1965, pp. 433-434) concluded from their data that each female didric
lays not more than four or five eggs during a breeding period. It is
not clear from their paper if by a breeding ‘‘period”’ they mean an
annual breeding season or a section of such a season, comparable to a
single clutch or to one nesting of a two- or three-brooded bird. Also,
as we have seen above in our discussion of egg intervals, there is some
reason to ask if this number accurately represents the total.

Removal of Host Eggs by Adult Cuckoos

The habit of removing one or more of the hosts’ eggs from a nest
has been known for a long time in many quite unrelated avian brood
parasites, cuckoos of several genera (Cuculus, Clamator, Chrysococ-
cyx, Cacomantis, etc.), cowbirds (Molothrus) and widowbirds (Vidua),
and possibly honey-guides (Indicator). While the correlation of this
habit with a parasitic mode of reproduction seems obvious, the origin
of the behavior is still completely unknown. As yet, no one has been
able to suggest an antecedent behavioral trait that might have been
altered into one of removal of eggs from the host’s nest by the para-
sitic bird. While egg removal by the adult parasite operates to its

88 U.S. NATIONAL MUSEUM BULLETIN 265.

own advantage by reducing the clutch size in the parasitized nest,
thereby ostensibly aiding the potential success of the young cuckoo,
it is inconceivable, that the laying adult can have any anticipatory
purpose. Actually, in many egg-removing parasites the evicting habit
of their newly hatched young takes care of possible nest-mate com-
petitors, rendering the earlier removal of one or more eggs less impor-
tant than it might appear to be. It would seem (but at this state of
our knowledge ‘‘seem”’ is the strongest word that may be used) that
the function of egg removal by the adult parasite is to keep the total
clutch in the nest from exceeding the limits acceptable to the incubat-
ing host.

The glossy cuckoos shed no new light on the early stages of this
particular behavioral trait, an evolutionary problem of great interest,
but one that remains blanketed in obscurity. In fact, we still do not
know if all the species even have the egg-removing habit, although
it is highly probable that all do. The habit has been reported on good
evidence for only four of the species: lucidus (unpublished data from
two observers), basalis (Atkins 1922, p. 314; Ingle 1912, p. 254; Ross
1919, p. 303); klaas (Pitman, in litt.), and caprius (Pringle 1946, p.
368; Skead, in litt.). To this may be added that it has been said to
occur in maculatus and in zanthorhynchus, although without direct
evidence. In the case of cupreus it has been suggested by Chapin
(1939, p. 203) that the male may remove an egg from a nest occa-
sionally, but it is not clear that this is necessarily connected with
the deposition of a substitute egg by his mate.

In connection with C. lucidus plagosus it may be noted that Braddy
(1949, p. 238) and Chalk (1950, pp. 219-220) both recorded seeing an
adult glossy cuckoo that flew to a thornbill’s nest (Acanthiza chrysor-
rhoa) and ‘‘clung by its feet to the lower part of the nest and rapidly
searched for and found the entrance, into which it thrust itself, leaving
only the end of the tail exposed. In a split second it withdrew itself
backward from the nest with the egg of the thornbill in its bill. This
it cast to the ground. A second time it plunged into the nest and
repeated the act, except that the second egg thrown out proved, cn
our investigating it, to be that of its own species . . . .”’ This obser-
vation is given here because it shows the instinctive nature of the act,
with no recognition of the difference between the eggs of the host
and of the parasite, which is what is tacitly assumed to hold as well
for the host in its usual acceptance of the alien egg. In this particular
instance both eggs were in an advanced state of incubation, which
indicates that a considerable number of days had elapsed since the
act of parasitism. It is, of course, impossible to tell if the egg-removing
cuckoo had also laid the egg in the nest. Even if it was the same bird,

AVIAN GENUS CHRYSOCOCCYX 89

the time between the two acts would make it uncertain that there
was any real connection between them.

In the case of C. klaas in Uganda, Pitman (‘in litt.) considered egg
removal the usual, normal procedure in all nests parasitized, and he
wrote me that such removal was performed only by the male cuckoos.
Unfortunately it is not clear on what observational evidence he
based this statement, and one can only await the publication of his
work to see what actual data he may have had. In my earlier account
(1949a, p. 137) I attempted to summarize what was then known by
saying that: Klaas’ cuckoo often removes an ege from the nest when
depositing its own, but whether it does so regularly or not remains to
be established. Several observers have seen one of these cuckoos with
an egg in its bill and have seen it break the shell and swallow the
contents. Captain Pitman also wrote me that he considered the re-
moval of one or more eggs from the nest by the adult male was also
characteristic of the didric, C. caprius.

In some species there is inferential evidence pointing to egg removal
by adult cuckoos, based on the fact that in parasitized nests the
number of the host’s eggs is often reduced from the normal clutch
size by the number of cuckoo eggs laid in it. This is true for instances
of parasitism recorded for the species osculans, malayanus, lucidus,
basalis, maculatus, xanthorhynchus, klaas, ewpreus, and caprius. As an
example, dealing in this instance with caprius, we may cite the work
of Hunter (1961, pp. 55-63), who studied the masked weaver, Ploceus
velatus, 12 of whose nests he found to be parasitized. In none of these
were there more than two eggs of the host in addition to that of the
cuckoo (in nonparasitized nests three eggs comprised the usual clutch),
an indication that the cuckoo parasite regularly removed at least one
of the host eggs from nests into which it deposited its own.

That host-egg removal is not invariably the case even in a species
as well known (relatively) as caprius is indicated by an observation
sent me by Neuby-Varty from Southern Rhodesia. He found a nest of
a tawny-flanked longtail, Prinia subflava affinis, with four eggs of the
Prinia and one of the didric cuckoo. Since in hundreds of nests of this
warbler Neuby-Varty had never found more than four eggs, he con-
cluded that the cuckoo had not removed any warbler eggs in this
instance.

As a further instance of lack of egg removal by the adult parasite,
we may cite Reed’s observations (1953, pp. 188-140). He studied the
didric’s parasitism on the red bishop, Huplectes oriz, and reported
that the cuckoo does not usually remove an egg of the host, “the
normal Red Bishop clutch [being] three eggs, and nearly all nests
containing cuckoo eggs [carrying] a total of four eggs... .”

However, the bulk of the observations on caprius suggest that egg

90 U.S. NATIONAL MUSEUM BULLETIN 265

removal is frequent, probably more often present than absent, from
the picture. We may mention the case reported by Pringle (1946, pp.
368-369), who saw a didric cuckoo leave the nest of a Cape sparrow,
Passer melanurus, with one of the sparrow’s eggs in its bill. It flew
to a nearby tree where it broke the egg shell, ate some of the contents,
and dropped the shell fragments to the ground. Pringle kept the nest
under daily observation and found that the cuckoo (presumably the
same bird) returned the following morning and again the next day,
each time removing one sparrow egg and laying one of its own
(all three cuckoo eggs so similar as to make it highly probable that
they were all from the same hen). Pringle’s description suggests that
the egg removing was done by the female didric, not by her mate as
Pitman’s statement (supra) might lead one to assume. However,
Pringle did not specifically state that he observed the second and third
egg removal, but only that the first was done by a female cuckoo.

Ottow and Duve (1965, p. 434) concluded, from Duve’s extensive
data on didrics parasitic on a colony of red bishops near Johannes-
burg, that the adult cuckoo removed eggs of the host only from nests
in which there were more than two eggs. Occasionally two host eggs
were missing from a nest, which these authors interpreted as implying
that a second didric hen was involved in the particular instances. In
six nests, each with two didric eggs, four no longer contained any of
the bishop eggs. Eggs of the didric were found with one host egg in 17
nests, with two host eggs in 26, with three host eggs in 4, and with
four host eggs in only a single nest. Duve assumed, but showed no
real proof, that the female didric did the actual removal of the eggs.

In our present study we are looking primarily for evidences of
evolutionary change within the genus Chrysococcyz, and must admit
that present data fail to show any progressive, or regressive, alteration
in this particular segment of the parasitic behavioral program. It may
be that fuller knowledge of all the species will indicate a trend toward
greater utilization of egg removal in the behavioral nexus associated
with brood parasitism in certain species and less in others. The glossy
cuckoos arose from an earlier parasitic stock which already had the
habit of removing eggs from the nests of their hosts, and, so far as we
may see, they have not altered the expression of this trait. In the
European cuckoo, Cuculus canorus, which, in the present state of our
knowledge, must serve as a “‘standard of comparison,” the male has
not been found to be involved in the removal of eggs from host nests.
If Pitman’s statement should be found to have general validity, this
involvement of the male may shed some light on the particular devel-
opment this portion of parasitical behavior has undergone in the glossy
cuckoos.

AVIAN GENUS CHRYSOCOCCYX 91

Host-parasite nestling relations

Aside from the evicting habit by which the young cuckoo eliminates
its nest-mates (discussed in the next section), a few other aspects of
the nest-inhabiting period of the parasite’s life call for comment.
Although the available data are still incomplete, they are here given
more as a basis for future additions than as a statement of any finality.
The topics of biological interest are: the length of the incubation period
of the cuckoo’s eggs, the duration of the nestling stage, and the dura-
tion of attentive behavior on the part of the host after the young
parasite is fledged, i.e., after it leaves the nest.

The incubation period has not been reported for any of the glossy
cuckoos except C. caprius, and in that species the few published state-
ments are not at all harmonious. Skead (1947, pp. 23-24) wrote that
the incubation period was 10% days (in a nest of the Cape weaver,
Ploceus capensis olivaceus). From piece-meal data on several nests
containing caprius eggs, I estimated (1949a, p. 163) it to be a day
longer. More recently, Hunter (1961, pp. 55-63) studied the para-
sitism of caprius on the masked weaver, Ploceus velatus, and concluded
that the eggs of the cuckoo took about 12 days to hatch. In the case of
C. osculans, Chisholm (1935, p. 70) wrote of a nest of a speckled war-
bler, Chthonicola, with an egg of osculans and stated that “two weeks
later the egg had hatched... .’ This is the nearest to a statement
of the incubation period I have found for this species, and it was not
written as an accurate, precise measurement. Inasmuch as any short-
ening of the incubation period would seem to be a selectively critical
factor in a group of brood parasites, it would be very interesting to
know if the glossy cuckoos reveal any adaptive differences, even slight,
in the duration of their prenatal development. It is not clear from
present fragmentary data if we can assume that the incubation period
is shorter in caprius than in osculans; more data on these two and on
the other species of the group are needed.

The duration of the nestling stage (from hatching to fledging) has
not been recorded for any of the Australian and Asian species of
Ohrysococcyx; in the case of klaas the nestling period was at least
12 days in a nest of the amethyst sunbird, Chalcomitra amethystina
and it was suggested (Friedmann 1949a, p. 146) that the exact length
of the period might vary somewhat with different species of fosterers.
In caprius, Skead (1947, pp. 23-24) found the nestling period, with
the Cape weaver as a host, to be 10 to 15 days; Pitman (in Friedmann
1949a, pp. 180-181) found a young caprius, about a fortnight old,
in a nest of a sunbird, Nectarinia erythroceria, while Hunter (1961)
found that a young caprius remained in the nest of a masked weaver
for 20 days. R. A. Reed (in litt.) found a young didric, C. caprius,

92 U.S. NATIONAL MUSEUM BULLETIN 265

hatched in a red bishop’s, Euplectes orvz, nest, had a nestling period
of between 19 days, 18 hours, and 22 days. The reason for this uncer-
tainty may be seen from the following details. On March 4 at 7:15
a.m. the nest contained four identical, plain blue eggs, and at 12:15
p-m. on March 5, it contained one hatched didric cuckoo and three
eggs. At 6:30 a.m. on March 25 the didric cuckoo chick was still
present in the nest, but when this nest was examined again at 6:30
a.m. on March 26 it was empty and deserted.

In nests in which the cuckoo eggs hatch several days later than
those of the host (i.e., probably nests parasitized after incubation
has begun in the host’s own eggs), the young parasite is unable to
evict the larger, heavier young of its foster-parent. On this point R.A.
Reed sent me the following notes, which may be given in toto.

It is by no means always the didric chick which hatches first
when a nest is parasitized by this species. Out of a total of 40 nests
which I found parasitized by this cuckoo and a total of 37 which
I have found containing the young of this cuckoo, three contained
cuckoo chicks considerably younger than their nest mates (the
offspring of the host). On February 22, 1955 I found a newly hatched
didric chick in the nest of a red bishop together with two red bishop
chicks approximately seven days old. When I revisited this nest
on March 2 I found the didric chick dead in the bottom of the nest
apparently trampled to death by its nest mates. On March 2, 1955
I found in the nest of a Cape sparrow not more than 100 yards from
the above red bishop nest, a newly hatched didric cuckoo chick
together with one addled Cape sparrow egg and a Cape sparrow
chick approximately six to seven days old. When I revisited this
nest on March 4 the Cape sparrow chick and egg were still present
with the cuckoo which was calling fairly loudly for food. Unfortu-
nately, on my next visit this nest had been robbed of all its contents.
The third case was that of a didric cuckoo chick which I judged to be
approximately seven days old (it was quite naked) in a Cape sparrow
nest which it shared with three nearly fully-fledged Cape sparrow
chicks . . . . This didric chick was calling so lustily for food that it
could be heard from 15 to 20 yards away.

From these records it would appear that when the didric chick is
hatched several days later than its nest mates it is incapable of evict-
ing them and is sometimes reared with them. Yet it appears that if
all the eggs in the nest are hatched at about the same time the didric
chick evicts the young of the host. As an example I cite a red bishop’s
nest in which I found one didric cuckoo chick and one red bishop
chick both approximately two days old on January 15, 1955. On
January 17 when I again visited this nest it contained only a didric
cuckoo chick. On another occasion I found a red bishop’s nest

AVIAN GENUS CHRYSOCOCCYX 93

containing 5 similar eggs and when I visited it on February 5, 1956 it
contained two red bishop chicks, one approximately 24 hours old and
the other freshly hatched together with one didrie chick approxi-
mately one to two days old. When this nest was again visited on
February 11 it contained only a didric cuckoo chick. .

In the case of the European cuckoo, Cuculus canorus, the habit of
the very young nestling of evicting its nest-mates from the nest is
always described as facilitated by the hollow, somewhat concave
shape of its back, affording a place on which to balance the egg or
young to be evicted. No such hollowing has been described for any
of the glossy cuckoos, but the didric, C. caprius, does have a decidedly
flattened back which is somewhat hollowed by the action of the bird,
which in the process of evicting usually raises its featherless wings
above the plane of its back to help balance the object it is about to
evict. Otherwise it would be difficult to see how the young cuckoo
could carry an egg almost its own size up a perpendicular nest wall
several times it own length.

Mellor (1917, p. 18) noted of C. éasalis that a newly hatched chick
had an “abnormal spike” at the alula and that its claws were curved
and exceedingly sharp. This has not been noted in other species of
glossy cuckoos.

The length of time after fledging during which the fosterer con-
tinues to feed the young parasite is of interest insofar as it interferes
with the host’s renesting and rearing a brood of its own. The survival
of the population of the host species is clearly of importance to the
parasite if the latter is to continue to have an adequate supply of
host nests. The data available on four species of glossy cuckoos sug-
gest that each instance of parasitism may have a prolonged effect,
sufficiently lengthy to affect adversely the possible recuperation of
the host species. Thus, in the south Australian basalis Kikkawa and
Dwyer (1962, p. 171) found that the fledgling still gapes for food
from passing birds for as long as six weeks after leaving the nest, a
much longer period than the usual postfledging feeding period of the
host involved in this observation (Acanthiza chrysorrhoa). It was not
stated, however, that the Acanthiza actually gave much attention to
the young cuckoo for this long time.

In the African klaas, J. Paludan (in litt.) wrote me that at Leopold-
ville, Congo, he watched a pair of Cyanomitra verticalis that continued
to feed a young Klaas’s cuckoo which they had reared for at least 10
bays after fledging. A still-longer period was noted by Ryves (1959,
p. 175) who watched a pair of Nectarinia kilimensis feeding a fledgling
cupreus for 26 days after it left their nest.

The data on the didric, C. caprius, reared by a Cape weaver studied
dy Skead (1947), who found it to be fed by its host for about a fort-

267-562—68——_8

94 U.S. NATIONAL MUSEUM BULLETIN 265

night after leaving the nest, may be extended by the observations of
R. A. Reed in the Transvaal, who kindly sent me the following (in
litt.).

At 5:45 p.m. on March 13 a fully fledged didric chick in a red
bishop nest was about to leave the nest as I touched it. At 6:30
a.m. on March 15 when I revisited this nest the chick had left.
On March 19 I found this bird lustily uttering its hunger call
close to the nest, accompanied by a red bishop. This chick I kept
under daily observation. By March 21 it had moved approxi-
mately 50 yards downstream from the nest and by March 22
it had established itself in some shrubbery approximately 80
yards from the nest, where it remained for the rest of the period
during which I had it under observation. . . . The bird was seen
on March 22 sitting quietly for 15 minutes at a time; occasionally
preening; black sunbirds, Cape sparrows and _ streaky-headed
seedeaters close at hand in same tree but the chick ignored them;
immediately it heard a red bishop call it assumed the begging
attitude—drooping wings a-shiver and high-pitched twitter-
ing—before the foster parent arrives beside it. A moment later
the female red bishop alighted beside it and fed it with food
apparently from its throat or crop; feeding the chick in a series
of regurgitations before flying off. The chick continued to twitter
weakly and to shiver its drooping wings for several seconds after
the foster parent had left. . . . On March 25 it was still utter-
ing its hunger call and was attended by the female red bishop.
On this occasion it flew after its foster parent across the shrubbery.

At 6:30 a.m. on March 25, 1955 a didric chick was still occupy-
ing another nest of a red bishop approximately 150 yards down-
stream from that described above. At 6:30 a.m. on March 26
it had flown from the nest, being fully fledged. I continued to
record the presence of only one didric chick in the shrubbery
until April 3 when two juveniles were calling quite close to one
another. On April 4 both juveniles were present in the same tree.
This was the last occasion on which I recorded two juvenile
didrics together in this area. I continued, however, to record a
single juvenile which, on April 6, after being fed by a female red
bishop with 44 regurgitations from its crop or throat, flew in
swift pursuit of its foster parent, twisting and weaving for ap-
proximately 100 yards to a mulberry tree. Watching this bird
on April 9 I noted that it was still being fed by its foster parent,
which it vigorously pursued after each feeding although still
remaining in the close vicinity of the shrubbery patch. On April
11 I recorded that this chick now appeared very green—not
coppery—on the back and was still begging vigorously from the
female red bishop. April 12 was the last date on which I saw
this bird, which never, during my observation of it, had strayed
more than 200 yards from its original nest site. As will be noted,
this bird could have originated from either of the two red bishop
nests recorded in this area so that the maximum post-nestling

AVIAN GENUS CHRYSOCOCCYX 95

period during which this bird could be said to have remained
with its fosterer was 28 days and the minimum 18... .

The same observer found the period of postfledging feeding of
caprius by masked weavers, Ploceus velatus, lasted from 22 to 26
days; and by Cape sparrows, Passer melanurus, from 17 to 37
days! Because of their unique richness in detail, further quotation
from Reed’s notes seem desirable.

On December 23, 1954, a juvenile didric was uttering the
hunger call and was attended by Cape sparrows. This bird I
observed almost daily and, on December 31, it was joined by
another juvenile didric also waited upon by Cape sparrows.
Subsequent to that date I observed only one didric in company
with Cape sparrows in this area and the last time I saw this bird
was January 29, 1955. During this period, under close observa-
tion for nearly a month, I always found this didric within a radius
of approximately 50 yards of the tree where it was first seen.
Because there were two didrics together at one time I cannot say
which of the two remained in the area to the last and I must
therefore state that the maximum post nestling period was 37
days but the minimum was at least 29.

I have one more postnestling record for a didric reared by
Cape sparrows and that is of a chick which was fully fledged in a
Cape sparrow nest at 6:30 a.m. on March 11, 1955 and which
had left the nest by 6:30 p.m. on the same day. This chick re-
mained in this vicinity—I always found it within a radius of
approximately 30 yards of a central point—until March 28th,
giving a period of 17 days ....

A parasitic bird, reared by any of a number of possible host species,
is aided by a fairly broad tolerance of food items and even of feeding
methods. Thus, the method of feeding the fledgling didric cuckoo
by red bishops is quite different from that employed by either the
Cape or masked weaver or by the Cape sparrow. The red bishop
invariably feeds the young with regurgitations from its crop. Reed
informed me that on several occasions he counted more than 40 of
these short, jerky regurgitations in a single continuous feeding.
On the other hand, the masked and the Cape weavers bring a sizable
erub or other insect, and each feeding operation consists of a single
offering. Whereas these birds feed their own young and their parasitic
young on insects exclusively, the red bishop uses soft seeds extensively.
The droppings of young didrics reared by red bishops often are full
of small grass seeds.

While the cuckoo young in general may thus experience a more
varied diet than do the young of any one of its fosterers, there are,
of course, obvious limits to what it can take in its stride. That all
the glossy cuckoos are parasitic on small passerine species in itself
limits the range or variety of their nutriment.

96 U.S. NATIONAL MUSEUM BULLETIN 265

Eviction of nest-mates by nestling cuckoos

Like the related genera Cuculus and Cacomantis, Chrysococcyz also
evinces the behavior pattern of eviction of nest-mates by the newly
hatched young. As in the other two genera, this habit is dispalyed
only in the first days of the nestling’s life and disappears by the time
the young cuckoo’s eyes begin to open. Eviction of nest-mates, either
young or eggs, has been observed and recorded for five species of
Chrysococcyx—lucidus, basalis, osculans, klaas, and caprius, and in-
ferred, without actual direct observation, for maculatus, xanthorhyn-
chus, and cupreus. In all probability the habit occurs in the other
glossy cuckoos as well, but as yet no data are available on them."

In the case of C. lucidus, Oliver (1955, p. 535) concluded that the
parasitism of this species must have a considerable effect on the popu-
lation of its chief host in New Zealand, the gray warbler, Gerygone
igata, whose “‘first brood. . . unless delayed, escapes the attention of
the cuckoo but [whose] later broods suffer heavy casualties in their
nestling stage as the young cuckoo invariably throws out all eggs and
young from the nest it occupies... .”’ In other species of Chrysococcyx
it appears that eviction of nest-mates is frequent, but not invariable.
Both Pitman and Chapin (ir Friedmann 1949a, pp. 180-181) have
sent me notes on nests containing young of the host and of the cuckoo
(caprius), but we do not know if these were instances where the
young parasite made no effort to oust its companions or if it tried to
do so but failed.

In a previous discussion (1956, pp. 404-405) I pointed out that no
one had yet made a direct observation of the actual evicting act by a
young caprius, a statement that is still true a decade later. The
precise age, in days, at which the newly hatched young cuckoo be-
comes an evictor and the age at which it ceases to be one has been
reported with some variation. Thus, Skead (1952, pp. 7, 9) noted that
a nestling caprius in a Motacilla nest made no effort to oust the two
eggs of the host for its first two days, after which it proceeded to evict
them both. In a Ploceus capensis nest, a young didric evicted an egg
and a newly hatched young of the fosterer on its second day. In
another Plocews nest the young parasite was half way through its

11 For pertinent published references on eviction of nest-mates see: lwcidus—
Campbell 1901, p. 581; Dickison 1928, p. 151; Oliver 1955, p. 535; basalis—
Campbell, 1901, p. 579; de Warren 1926, p. 78; Dickison 1928, p. 151; Leach 1929,
pp. 177-182; osculans—Chisholm 1935, p. 70; maculatus and xanthorhynchus—
Baker 1942, p. 155; klaas—Friedmann 1956, pp. 399-400; MacLeod and Hallack
1956, pp. 2-5; caprius—Friedmann 1956, pp. 404-405; Hunter 1961, pp. 55-63;
Reed 1953, pp. 138-140; Skead 1952, pp. 7, 9; Skead, 7n Rowan and Broekhuysen
1962, p. 28. In addition to these I have numbers of unpublished notes from Pitman,
Chapin, and other observers in my files.

AVIAN GENUS CHRYSOCOCCYX 97

third day when it ousted its nest-mates. On the other hand, Reed
(1953, pp. 138-140) reported that a nest of EHuwplectes oriz contained
one chick and two eggs of the bishop bird when a didric egg in the
nest hatched; four days later the nest was found to contain three
young bishops and the young didric cuckoo, indicating that no evic-
tion had transpired. In another nest of a red bishop Reed found only
a young caprius about four days old. He then put two Euplectes eggs
in the nest, and 4% hours later both were out of the nest. This sug-
gests that the evicting habit persisted until the didric’s fourth day at
the least. Notwithstanding the apparent absence of eviction in the
first case reported, Reed concluded that the nestling caprius “appears
to eject the eggs or young of its host in all cases because in no single
instance were large Didric Cuckoo chicks found with Red Bishop
young in the same nest... .”

Hunter (1961, pp. 55-63) concluded that the young cuckoo was
unable to eject chicks of the masked weaver, Ploceus velatus, if it
hatched too long after they did. Unfortunately, no more explicit time
was given, but it would seem to be a matter determined by the size
and weieht of the Ploceus chicks, plus their increased ability to with-
stand the actions of the would-be evictor.

The young of normal, self-breeding birds are often crowded in the
nest and cannot help but push against each other, although they
make no attempt to evict. Furthermore, the crowding usually comes
later when the young are larger, and since the evicting habit of the
young cuckoo is restricted to the first few days, before the nest is
really crowded, it follows that it is not a result of crowding but is
merely a contact reaction.

We know that the young of some parasitic cuckoos, such as the
crested cuckoos, Clamator, and koels, Eudynamis, do not practice
eviction and that in the nests on which they are reared crowding often
is very great. We know also that parasitic widowbirds, Vidua, and
cowbirds, Molothrus, do not have the evicting habit, although not
infrequently the host young are starved out by the parasite and their
dead bodies removed by their own parents.

The nest-mate evicting habit reveals no alteration in the glossy
cuckoos; it is apparently a trait that was already present in the stock
from which they evolved, and, as far as present observations go, they
have neither added to, nor subtracted any features from, its mode of
expression. In some Ploceine nests it is often difficult for the young
didrics to evict their nest-mates, yet species of Ploceus with domed
nests with tubular entrances are among the commonest victims of
caprius. Similarly, the nests of many of the sunbirds used frequently
by kiaas present difficulties for the would-be evictor as they are often
deep, frail, pouchlike structures. It might be said of the glossy

98 U.S. NATIONAL MUSEUM BULLETIN 265

cuckoos that they have retained the evicting habit in spite of their
wide use of “difficult”? nests—certainly many of them more difficult
as eviction sites, with all the violent exertion and pushing involved,
than those commonly parasitized by species of the genus Cuculus.

Fledgling feeding by adult cuckoos

The atavistic behavior pattern of feeding fledgling glossy cuckoos
by adults of the same species has been observed and recorded for
four of the members of the genus Chrysococcyxz (caprius, cupreus, klaas,
and lucidus) with a total of at least 33 independent observations, not
counting such old, unsupported statements as that of Heuglin (1871,
p. 777), who noted adult caprius feeding young ones on several occa-
sions in October 1861, at Keren, or indefinite, dataless observations
along the same lines by others. These 33 cases are divided as follows:
caprius 15 (plus some incompletely described ones), cupreus 2, klaas
12, and lucidus 4 cases in print.

The number of these definite observations is sufficient to indicate
that fledgling feeding is neither uncommon nor unusual, while the
assiduous and repetitive feedings in some of these cases make it im-
possible to assume that they were chance happenings which were
based on the reactivation of a residual responsiveness by a passing
adult cuckoo to the food-begging of the young.

In earlier discussions of this intriguing and theoretically significant
tendency I was inclined to wonder if the actual observations might
not have been of instances of courtship feeding, in which case either
the observer assumed the fed bird to be a young one rather than a
potential mate or that the food-bringing cuckoo itself might have
mistaken a well-grown fledgling for an adult female. Some years later
I found that Watson and Bull (1950) had raised a similar question
about Hursthouse’s (1944) record of fledgling feeding by the glossy
cuckoo, C. lucidus, in New Zealand, even though in that instance the
presence of the foster-parent, Gerygone igata, enhanced the likelihood
that the fed bird was, not an adult, but a young cuckoo. My original
question stemmed from the fact that the early records involved adult-
male cuckoos only in instances where the sex of the feeding bird was
specifically mentioned. Even now, with a greater number of such
cases on record, there is still only meager evidence that adult females

12 For pertinent references to these cases see: Baird 1945; Benson and Serventy
1957; Fell 1947, p. 513; Fulton 1910; Graham 1940, p. 4; Haydock 1950; Heuglin
1871; Holman, in Bannerman, 1933, Hursthouse 1944; Maclaren 1952, 1953;
Millar 1926, 1943; Moreau 1944; Moreau and Moreau 1939; Oliver 1955; Olivier
1957; Ottow and Duve 1965, p. 432; Pike, in Friedmann, 1956; Robinson 1950,
p. 107; Smith 1957, p. 309; Symons, in Friedmann 1949a; Thomas 1960; van
Someren 1939; and Worman 1930.

AVIAN GENUS CHRYSOCOCCYX 99

of these cuckoos do feed fledglings of their own kind. Out of the 33
instances on which I have compiled data, the sex of the food-bearing
bird was stated in only 13 cases, and in 12 of these it was male. In
only a single instance, of which I was unfortunately unaware at the
time (Millar 1926, p. 28) was the food-bearing bird stated to be a
female, and this account was written in so loose and anecdotal a
manner that it seemed too unfirm a basis for a unique unit of informa-
tion. In all the other cases, either the sex of the food-bringing bird
was not mentioned, or some element of uncertainty was expressed.

Maclaren (1952, pp. 684-685; 1953, p. 167) reported a case that may
have involved a female as well as a male food-bringing didric cuckoo.

Once a male and what I considered to be a female each caught
caterpillars and returned to perches two feet apart four times
running, at intervals of 40 to 45 secs., without taking apparent
notice of one another.

There were at least five birds concerned in this orgy—the
definite male, the presumed female... and three others which
may have been female or immature; these spent much time
chasing one another. Twice in half-hour stretches one of these
three fed another female or immature bird, to apparent repletion.
Each time the catcher returned to the neighbourhood of the
other stationary bird it displayed, with drooping wings, cocked
tail and extended neck. As it hopped nearer it gave four or five
bobs, and uttered three or four low calls of the type associated
with the species. The caterpillar was taken without any display
by the recipient ....

That the food bearers in this case always displayed when offering
the caterpillar suggests (but does not prove) that they were adult
males. Similarly, in a case concerning C. klaas, Baird (1945, pp.
565-566) reported seeing an adult male catching dysdercid bugs
and feeding them to two young cuckoos. He also stated that a week
or so earlier a friend had seen a “‘pair of Klaas’s Cuckoo fly back-
wards and forwards . . . with Dysdercid bugs ... . It can only
now be presumed that the parent birds must at this time have been
feeding the young while still nestlings ... .’’ There is no proof,
however, that the “pair” of klaas cuckoos actually were a pair or
that both (or either) had been bringing the bugs to any young cuckoos,
in or out of the nest. The fact that Baird saw the adult male feeding
two fledglings may suggest that it was acting in a parental way,
but it might also be that it was indulging in courtship feeding with
two hens simultaneously.

Another fact that caused me to question the basic nature of fledgling-
feeding behavior is that in the cases most completely reported—the
relatively few with corroborative details—the feeding male presented
each morsel of food, usually a caterpillar, with a definite courtshiplike

100 U.S. NATIONAL MUSEUM BULLETIN 265

ceremony, raising first the head and then the tail and going through
somewhat stiff, jerky, bowing motions. Moreau (1944, pp. 98-100)
noted that the male sometimes bowed once or twice after his food
offering had been accepted by the bird he was feeding. Moreau
observed that this was quite similar to the actions of a male caprius
watched by Jackson as it fed a female in the presence of a fledged
young bird, and concluded that, if his own observations involved
the feeding, not of adult females, but of fledglings, as he thought
they did, then it would appear that the males use the same pres-
entation ceremony with fledged young as with adult hens.

Some idea of the repetitive extent of individual feedings, suggestive
of the fact that the catering adult was not merely indulging in court-
ship feeding, may be gathered from the following cases: Maclaren
(1952, pp. 684-685; 1953, p. 167) recorded one feeding “bout”’ that
involved 6 caterpillars in 2 minutes 35 seconds; Moreau (1944)
recorded one male didric bringing 21 caterpillars in 15 minutes to
one presumed fledgling and also cited a case by Elhott of C. klaas
“assiduously” feeding a fledgling of that species.

If, as outlined in our hypothecated phylogeny within the genus
Chrysococcyz, the New Zealand-Australian species, lucidus, is more
‘primitive’ than the African species, klaas and caprius, discussed
above, or if it merely represents another, distinct portion of the
genus, it is of interest to know that it too has been observed to feed
fledglings of its own kind. In other words, this atavistic behavior
appears, from present meager data, not to be restricted to just one
portion of the genus.

Baird (1945) and Moreau & Moreau (1939, pp. 298-299) suggested
that the relationship involving attentive behavior of an adult to a
young of the same species of glossy cuckoo may become established
when the young bird is “hardly out of the nest . . . .” K. D. Smith
(1957, p. 309) also reported that in Eritrea in October he saw adult
didric cuckoos (not identified as to sex) on several occasions feeding
young “just able to fly.”” Actually, in C. lucidus Howe (1905, pp. 35-
36)" reported seeing the adult cuckoo come to a nest of Acanthiza
chrysorrhoa containing a nestling lucidus and feed it; “meanwhile the
foster-parents were in a great state of excitement and repeatedly
dashed at her until she left the vicinity.”’ The sex of the cuckoo was, of
course, merely assumed to be female. This observation has the merit of
eliminating any possibility that the adult cuckoo may have mistaken
a nestling for an adult, and it strengthens the conclusion that these
cuckoos do feed young of their own kind. In this connection one may

13 Howe’s paper contains a mixture of observations on Chrysococcyx lucidus and
Cuculus pallidus, but this note appears to refer to C. lucidus, although it was
interpreted by Moreau (1949) as Cuculus pallidus.

AVIAN GENUS CHRYSOCOCCYX 101

recall that Layard long ago (1875-84, p. 155) quoted Mrs. Barber to
the effect that C. caprius in South Africa remained near the nests
it parasitized, “watching over’ them. This, of course, is not evidence
in itself, but it makes one wonder what actual observations Mrs.
Barber may have had.

This leads us to a recently published statement. Ottow and Duve
(1965, p. 432), based on the latter’s extensive field studies in the
Transvaal, concluded that the tendency of C. caprius to feed its own
fledged young was sufficiently consistent and well developed to play
a role in restricting the size of the breeding territory of each adult
didric cuckoo, ethologically attached as it was to the nests from which
would emerge its future charges. They thought that this caused a
very real limitation on the freedom of movement of the didrics,
especially if compared with the unhampered movements of a non-
fledgling-feeder such as Cuculus canorus gularis. However, it is by no
means established that the latter cuckoo is not also territorial, and the
regularity of fledgling feeding by the didric needs further quantitative,
observational proof.

Benson and Serventy (1957, pp. 347-349) suggested that feeding of
young by the adult cuckoo may be due to the fact that those young
were reared by seed-eating fosterers and, in their need for insect food,
depended on their own species. This suggestion was answered by a
more probable one by Marshall and Moreau to the effect that, as
responsiveness to the food-begging calls and movements of the young
is still present—even if relatively vestigial—in the adult cuckoos, it
may have some survival value for those young reared on seeds and in
need of the animal protein of insect food.

Even if the recrudescence of attentive parental behavior may oc-
casionally have some such value for the recipients of it, this value
cannot be looked upon as explaining its occurrence. It would seem
more to the point to ask if species of fosterers that rear young para-
sites on seeds alone might be disadvantageous, or at least ill-adapted,
for the cuckoo, and if in time they might be eliminated from its selec-
tion of hosts. This line of thought would raise the related question as
to whether these particular victims are ‘normal,” regularly used
hosts at present or whether they are imposed upon only occasionally.

The basic, theoretical, biological interest attached to fledgling
feeding is that it is a revealing atavism. That it occurs in those cuck-
oos that also exhibit a tendency toward courtship feeding serves to
stress the similarity in the two behavior patterns. The persistence of
food-offering in courtship may well expedite the response to the
begging reactions of fledglings and may help to bring into expression
what must have been an ancestral habit prior to the advent of para-
sitism in the cuckoos.

102 U.S. NATIONAL MUSEUM BULLETIN 265.

In his study of display behavior of birds, Armstrong (1942, pp.
29-35) considered courtship feeding a “recrudescence of an infantile
mode of behaviour. . .,” and noted that it is usually accompanied
by a considerable amount of psychobiological excitation and appears
to be present mainly in species in which the pairing union is strong
and prolonged. The fact that this situation is probably not true of
the glossy cuckoos led me (1949a, p. 185) to suggest that when this
ancient, vestigial courtship activity appears in these birds it may be
lavished on fledglings as well as on prospective adult mates. It still
seems possible that the catering cuckoos (males in most instances)
may not always be aware of the maturity or immaturity of the indi-
viduals they feed. However, it does seem that they deliberately offer
food to birds too young to be mistaken for adults, so that, in part at
least, they are fledgling feeders as well as courtship feeders.

Moreau (1944) considered fledgling feeding an indication that the
whole picture of brood-parasitism was not as “advanced” or ‘‘per-
fected” in the glossy cuckoos as in some other genera of the family.
However, there are a good number of observations on the Australian
pallid cuckoo, Cuculus pallidus, that show it to indulge in fledgling
feeding at least as often, it not more frequently, than do the species of
Chrysococcyz. That such a habit is found in a member of the genus
Cuculus is more surprising, since this behavior has not been noted in
the European Cuculus canorus, the best observed of all parasitic
cuckoos. It shows that the extremely high development of speciali-
zation for brood parasitism in C. canorus is a specific and not a generic
matter. In his summarizing book on all that he knew of Indian and
European cuckoos, Baker (1942, p. 177) concluded that there was no
evidence to support the thought that any of these parasites ever
exhibit any interest in their eggs or young. While this suggests that
the Asiatic forms of Cuculus (canorus, optatus, micropterus, etc.) and
of Merococcyx, Cacomantis, Penthoceryx, Clamator, Surniculus, and
Chrysococcyx had not been found to feed fledglings, it certainly is not
true for the koel, Hudynamis scolopacea, which has been reported as
doing so not infrequently. The absence of Asiatic records of fledgling
feeding by Cacomantis is offset by Australian observations of this
behavior in the fan-tailed cuckoo, Cacomantis flabelliformis. Another
Australian cuckoo known to exhibit this trait is the large channel-bill,
Scythrops novaehollandiae."*

Fledgling, and even nestling, feeding occurs from time to time in a
number of species of cuckoos belonging to at least five genera. The
significant difference between Chrysococcyx and Cuculus in this regard

144 For pertinent references on Australian instances, other than Chrysococcyz,
see: Chisholm 1940, 1950; Friedmann 1949b; Hanscombe 1915; Howe 1905;
Jackson 1949; Learmonth 1949; Robinson 1950; White 1950.

AVIAN GENUS CHRYSOCOCCYX 103

is that this atavism is more widespread in the former, where it has
been noted in 4 out of 12 species, than in the latter genus, where only
1 out of 12 included species has been observed to exhibit this tendency.
Inasmuch as Eudynamis and Scythrops are monotypic, comparisons
with them are meaningless. Cacomantis is still too imperfectly known
to yield significant comparisons here. If the present absence of
fledgling feeding is to be interpreted as being due to its elimination
during the past history of each species and, conversely, if its presence
is taken to imply the opposite, the difference noted above for Chryso-
coccyx and Cuculus may be taken as an indication that the glossy
cuckoos, as a group, are not as advanced as Cuculus in their develop-
ment of brood-parasitism.

It may be mentioned that only a single instance of this type of
behavior has been reported for a single species of cowbird (Friedmann
1963, p. 27, ex Walton 1903) and none for any of the other groups of
parasitic birds, honey-guides, weavers, or ducks.

Summary and conclusions

The glossy cuckoos, forming the genus Chrysococcyx, are the
smallest members of their family, and by virtue of their small size
and their glossy, ‘metallic’ plumage are a natural assemblage,
closely related to, but distinct from, other genera of the Cuculinae,
especially Cacomantis and Cuculus. They probably originated in the
Australo-Malaysian area, possibly in Pliocene time, from the stock
represented today by the other two genera mentioned above or at
least from the common stock that also gave rise to them. All three of
these genera are very similar in their structure, in their habits, and
particularly in many details of their brood parasitism. While Cuculus
has come to occupy a much more extensive part of the earth’s land
surface than the other two and, in one of its species, Cuculus canorus,
has come to develop a degree of adaptive specialization unknown in
the other two, Chrysococcyz also experienced a greater geographical
and speciational expansion than has Cacomantis and it has come to
occupy a niche in its parasitism on small passerine birds in some parts
of the world—such as Africa, New Zealand, and some of the islands
of the South Pacific, where it is largely alloxenic with respect to
other cuckoos—as well as to flourish in other places—such as Australia
and southern Asia, where it is partly homoxenic with members of
both its related genera.

Two new terms, alloxenia and homoxenia are proposed to facilitate
thinking and discussion of brood parasitism. Alloxenia, with alloxenic
as its adjective, implies that different species of parasites use different
hosts, while homoxenia, with homoxenic as its adjective, conveys

104 U.S. NATIONAL MUSEUM BULLETIN 265

the thought of two or more species of parasites sharing the same
host species.

From its original locus Chrysococcyx expanded its range south-
eastward to include Australia, Tasmania, New Zealand, and the
highlands of New Guinea. From this area it moved westward into
northern Malaya, Burma, India, and southern China, and also to
Borneo and the Philippine Islands; later, from its Asiatic area of
occupancy, it progressed farther to the west and came to include
in its domain all of Africa south of the Sahara, although not the
islands of the Indian Ocean (Seychelles, Aldabras, Mauritius, Reunion,
Madagascar, the Comoros, etc.). Inasmuch as Madagascar became
separated from Africa in the Pliocene and inasmuch as no glossy
cuckoo occurs in that great island, it becomes necessary to postulate
a not earlier than Pliocene time for its westward spread, and, this,
in turn, implies a correspondingly earlier date of origin in the ancestral
homeland of the group.

The evolutionary implications of the current distribution of the
species and subspecies of glossy cuckoos are discussed following their
listing in the appendix (pp. 111-113).

Morphologically there are three groups of species within the genus.
The connections between the species of each group are obvious,
but those between the groups are conceivable only as inferences, since
the intermediate steps have long since disappeared. What appears to
be the earliest group comprises the obviously closely related species,
malayanus, lucidus, basalis, ruficollis, and osculans, the last named
one being a little more distinct from the others than any of them are
from each other. Then, with a gap in a strict chronology of characters,
comes a second group including meyeriz, maculatus, and zanthorhynchus.
Following this, with a still greater hiatus both geographically and
morphologically, comes the African group which includes flavigularis,
klaas, cupreus, and capris.

Similarly, in the development of irridescent, glittering plumage the
genus reveals a discordant, unchronological diversity, with great
development in meyerit in New Guinea, in maculatus and zxanthor-
hynchus in southern Asia, and in cwpreus in Africa, with a total loss
of this character in osculans of Australia and various degrees of in-
termediacy in malayanus, lucidus, basalis, ruficollis, flavigularis, klaas,
and caprius. The genus differentiated into a dozen species, some with
numbers of races, but within these dozen entities no one discernible
progression of evolutionary trends can be found that parallels their
hypothecated phylogeny. Close similarities, both in morphology and
in ethology, exist between some of them, such as malayanus, lucidus,
and basalis or between maculatus and xanthorhynchus, while other
species, such as osculans and caprius, are unique extremes.

AVIAN GENUS CHRYSOCOCCYX 105

More of a sequential, phylogenetic display of change can be found
through the genus in the matter of the ventral pattern of the first
pennaceous plumage. The young of the first of the three groups of
species mentioned above—malayanus, lucidus, basalis, and osculans—
are uniformly unbarred grayish-white below from the chin to the under
tail feathers; those of the other two groups have the underparts
heavily barred in their young, except for meyerti, which agrees in this
respect with the Australasian species, and, in so doing, acts as a perfect
“step” or intermediate between the Australasian group and the
Asiatic maculatus and zanthorhynchus. In its adult plumage meyerii
is already in line with the south Asian species; in its juvenal stage it
resembles malayanus, lucidus, basalis, and osculans.

The variety of expression of migratory behavior is likewise a matter
of development within the several species rather than a traceable
progression throughout the genus. The great range of migratoriness,
from none at all to annual long-distance movements of as much as
2000 miles over open seas without landmarks, previous experience, or
even communication and guidance between successive generations,
is amazing in scope. However, it reveals no continuous pattern across
the genus. For that matter, it shows no uniformity even within the
same species. Thus, C. lucidus has four races, two of which are highly
migratory and two are sedentary.

The main point of interest in this study has to do with the features
of brood parasitism exhibited by the members of the genus Chryso-
coccyx and particularly with clues to the course of evolutionary
changes in these features that a comparative survey might reveal.
The genus could hardly be expected to reveal any evidence as to the
origin and basic stages in the development of the parasitic mode of
reproduction, since it obviously evolved from a primordial cuculine
stock that was already entirely parasitic in its mode of reproduction
and that already had developed the evicting behavior in the very
young nestling and the egg-removing behavior in the adult. The glossy
cuckoos retained, to a greater degree than Cuculus (except for one
species, C. pallidus) and than most of the species of Cacomantis, the
atavistic habit of feeding fledged young of their own kind and, not
unrelated, the similar habit of courtship feeding of the adult hens by
the cocks.

The present study shows that the glossy cuckoos have, in the course
of their history, greatly enlarged their range of hosts, but that, while
doing so, individual species of Chrysococcyr have come to concentrate
on partly or largely different groups within that broader range of
hosts. Thus, C. malayanus is restricted to a great extent to warblers
of the genus Gerygone, although one of its races, C. m. russatus, has
expanded its fosterer selection to include other hosts as well. C. lucidus

106 U.S. NATIONAL MUSEUM BULLETIN 265

has retained a fixation on Gerygone in one of its races (C. l. layard?),
but has gone far afield in its use of many other birds in New Zealand
(C. Ll. lucidus) and especially so in southern Australia (C. l. plagosus),
where its hosts total some 75 species of many genera, although it
shows very marked preference for species of Acanthiza and to a some-
what lesser extent for Sericornis and Malurus.

C. basalis has the most extensive host catalog of any of the glossy
cuckoos, totaling some 100 species but showing a very strong inclina-
tion toward the use of wrens of the genus Malurus and, to a lesser
degree, species of Acanthiza, Rhipidura, Petroica, Hylacola, and other
warblers and honey-eaters. A great reduction in the number of species
of victims is characteristic of C. osculans, which is very largely para-
sitic on Chthonicola, with the eggs of which its own have a remarkable
similarity, and also on Pyrrholaemus. Of the host choice of C. ruficollis
we know nothing, but it may be expected to be somewhat similar to
that of C. malayanus and C. lucidus. Also, of the Papuan, C. meyerii,
there are as yet no data as to what birds it depends on to raise its
young.

The Asiatic C. maculatus and C. xanthorhynchus are parasitic on
sunbirds and warblers and a few other hosts, but, insofar as present
knowledge permits a generalization, the sunbirds, Arachnothera and
Aethopyga are their mainstay.

Of the African species, no hosts are yet known for C. flavigularis:
for the others a large number are now recorded, and there is consider-
able overlapping, or what I have here termed homoxenia, among them.
However, caprius is far more prone to use weavers, Ploceidae, while
klaas tends to use warblers, Sylviidae, and sunbirds, Nectariniidae, to
a great extent; cupreus is a less selective parasite, using a common
bulbul, Pycnonotus, more often than any other host, but also using
weavers, warblers, and sunbirds.

On the whole, Chrysococcyr presents an uneven performance, in an
evolutionary sense, in the development of host-adaptive, individually
divergent egg morphism, with the related development of individual,
and even of specific, host specificity. The species which show these
traits best developed are osculans, with a single egg type and one
most regular, favorite host choice, and caprius, with several ovo-
morphs, three of which are more or less related each to a regular,
frequent host species. Inasmuch as these two cuckoos are quite far
apart in the phylogeny within the genus and inasmuch as none of the
other species show any comparable degree of adaptive egg morphism,
one can only conclude that the genus Chrysococcyr has not revealed a
continuity of adaptive evolution in this important feature of brood
parasitism. What has been achieved in this direction has transpired
within individual species.

AVIAN GENUS CHRYSOCOCCYX 107

Egg coloration shows agreement between some closely related
species and discordance between others. Thus, the eggs of the related
malayanus and lucidus are plain olive-bronze, but in the also closely
related basalis they are white, speckled finely with pinkish red; in
osculans they are deep mahogany-reddish; while in klaas and caprius
they are variable, the last named species having half a dozen ovo-
morphs, varying from unmarked white, pale greenish, pale or darker
bluish to any of these colors or even pale, creamy grayish, variously
spotted or even blotched with shades of brownish and grayish.

In size the eggs of the glossy cuckoos are relatively small for the
body size of the birds, but they show none of the drastic reduction in
size found in the European cuckoo, Cuculus canorus. In many para-
sitized nests the Chrysococcyx eggs are somewhat smaller than those of
the host species, in others the reverse is the case. Apparently the need
for reduction in egg size has been less than in the larger cuckoos that,
like Chrysococcyz, use nests of small passerine victims.

As indicated in the present survey and discussion of host selection,
host specificity, and egg morphism, the glossy cuckoos as a group have
evolved diverse host preferences and have done this to varying degrees
of rigidity or intensity, but they have not gone so far as to evolve
gentes within any of their species, as has Cuculus canorus. All of the
changes described in this paper, all the expansions of the range and
variety of host nests utilized, and the contracting specializations
within these enlarged choices of hosts, have made it possible for the
glossy cuckoos to find relatively noncompetitive niches, as far as their
congeners are concerned, and yet to take advantage of a vast passerine
fauna in three continents and many oceanic islands. The degree to
which sympatric species of Chrysococcyr have become mutually allo-
xenic is an indication of evolutionary change; the degree to which
they are still homoxenic implies the distance they have still to travel
toward a theoretically perfect intraspecific independence and non-
competitive coexistence.

U.S. NATIONAL MUSEUM BULLETIN 265, PLATE 1

Australian and Asiatic Glossy Cuckoos

1. C. malayanus; 2. C. lucidus; 3. C. basalis; 4. C. ruficollis; 5. C. osculans; 6. G:
meyerii (male and female); 7. C. maculatus (male and female); 8. C. canthorhyn-
chus (male and female).

U.S. NATIONAL MUSEUM BULLETIN 265, PLATE 2

African Glossy Cuckoos

9. C. flavigularis (male and female); 10. C. klaas (male and female); 11. C. cupreus

(male and female); 12. C. capriws (male, female, and hepatic young female).

Appendix

1. The existing species and their distribution

The forms of the genus Chrysococcyx and their ranges are as follows:

1. C. malayanus (Raffles): Malay Peninsula (from Patani southward), the
Philippine Islands, the East Indies (Java, Sumatra, Borneo, Celebes), the
Moluccas, the Lesser Sunda Islands, New Guinea, and adjacent islands, and
northern Australia. In this vast range the species has become differentiated into
11 races, as follows:

C. malayanus malayanus (Raffles): Malay Peninsula from Patani southward,
the Philippine Islands (Negros, Mindanao, Basilan, Tawi Tawi, Bongao), and
Sumatra.

C. malayanus albifrons (Junge): Java.

C. malayanus aheneus (Junge): Borneo (including Maratua Island).

C. malayanus jungei (Stresemann): central and southern Celebes.

C. malayanus rufomerus (Hartert): Lesser Sunda Islands (Roma, Damar, Leti,
Moa, Sermatta, Timor, Sumba, Kisar[?]).

C. malayanus salvadorii (Hartert and Stresemann): Babar Island (known only
from the type from Tepa).

C. malayanus misoriensis (Salvadori): Biak Island in Geelvink Bay.

C. malayanus poecilurus (G. R. Gray): Western Papuan Islands, Wagieu,
Misol, Aru Islands, Vulcan Island, Dampier Island, Fergusson Island, all of New
Guinea except part of the south coast.

C. malayanus russatus (Gould): Cape York Peninsula of northern Australia,
and the Merauke area to the Mimika River, of southern New Guinea.

C. malayanus minutillus (Gould): northern Australia from the Kimberly district
in the northwest, to Arnhem Land and to northern Queensland south of the range
of russatus; also Melville Island (considered by some as a distinct species, although
poorly differentiated from malayanus).

C. malayanus crassirostris (Salvadori): the Moluccas (Halmahera, Ternate,
Buru, Ceram, Amboina, Goram, Tenimber Islands, Kei Islands, Soron. (one
dubious record), northwestern New Guinea; and also listed from Kisar Island,
from which place the race rufomerus has also been reported (no Kisar specimens
seen by the author).

2. C. lucidus (Gmelin): breeds in New Zealand, Chatham Islands, possibly
Norfolk and Lord Howe Islands, Tasmania, southern Australia, the Santa Cruz
Islands, Banks Island, the New Hebrides, the Loyalty Islands, New Caledonia,
Rennell and Bellona Islands; in winter in the Lesser Sunda Islands, New Guinea,
the Solomon Islands and the Bismarck Archipelago. The species is divided into
four races, as follows:

C. lucidus lucidus (Gmelin): breeds in New Zealand and the Chatham Islands
(possibly also in Norfolk and Lord Howe Islands) ; winters in the Solomon Islands,

15 According to Smythies (1960, p. 255): “There is a possibility that a similar but distinct species occurs on
Kinabalu ... ,”’ but I have seen no evidence, or specimen material of it.

109
267—562—68—9

110 U.S. NATIONAL MUSEUM BULLETIN 265

Nissan and Feni Islands (east of New Ireland), and the Bismarck Archipelago;
migrates through the Louisade Archipelago.

C. lucidus plagosus (Latham): breeds in Tasmania and southern Australia;
winters in the Lesser Sunda Islands (Lombok, Sumbawa, Flores, and Wetar), New
Guinea, and perhaps in the Bismarck Archipelago.

C. lucidus layardi (Mathews): resident in the Santa Cruz Islands, Banks
Island, the New Hebrides, the Loyalty Islands, and New Caledonia.

C. lucidus harterti (Mayr): resident in Rennell and Bellona Islands.

3. C. basalis (Horsfield): breeds in southern Australia and Tasmania; winters
chiefly in the Sunda Islands from Java to Sumbawa; recorded also from the
Malay Peninsula, Sumatra, Borneo (once), North Natuna Islands (once), Kangean
Islands, Christmas Island (in the Indian Ocean), and Celebes (once); on migra-
tion noted on the Aru Islands and the Cape York Peninsula.

4. C. ruficollis (Salvadori): resident in the highlands of New Guinea, chiefly
at altitudes above 6000 feet, occasionally lower (4000 feet).

5. C. osculans (Gould): breeds in Australia, chiefly in drier areas than basalis
and lucidus, but overlapping them and extending much farther north across the
interior; relatively rare in the southern coastal areas; absent from Tasmania; the
extent to which it is migratory is not yet clearly known, but it has been recorded
from Cape York, the Aru and Kei Islands, and from Batjan.

6. C. meyerit (Salvadori): resident in the tropical forests, second growth, and
clearings, of New Guinea at altitudes up to 4000 feet, commonest at 2500 feet.

7. C. maculatus (Gmelin): breeds from the central Himalayas west as far as
Kuman, through Assam, southeastern Tibet and Szechwan, to Hupeh, south to
Yunnan, Burma (in evergreen forest up to 8000 feet), and Annam. In winter or
on migration, in India, Hainan, Cochinchina, Malay Peninsula, and Sumatra.

8. C. canthorhynchus (Horsfield): resident (possibly partially migratory locally)
from Assam, southwestern Yunnan, and Burma (where reported only in the
evergreen-forest areas), and southern Annam, south to eastern Bengal, the
Malay Peninsula, Siam, Cochinchina, the Andaman and Nicobar Islands, Sumatra,
Simalur, Sipora, the Lingga Archipelago, Java, Borneo (where sparingly distrib-
uted in the lowlands, and found in gardens in Sarawak, on the edges of man-
grove swamps, and on the seashore), the North Natuna Islands, and the Philippines
(Luzon, Mindoro, Samar, Cebu, Leyte, Basilan, and Palawan). The species has
been divided into three races, one of which may be doubtfully valid, as follows:

C. xanthorhynchus xanthorhynchus (Horsfield): range as above except for the
Philippine Islands, other than Palawan.

C. zanthorhynchus amethystinus (Vigors): Philippine Islands, except Palawan,
as given under the species range.

C. xanthorhynchus bangueyensis (Chasen and Kloss): only known from Banggi
Island off the north coast of Borneo (doubtfully distinct from the nominate race,
but its status requires additional material for clarification).

9. C. flavigularis (Shelley): resident in the forests from Sierra Leone to Togo
from southern Cameroon eastward across the Congo to the Uelle and to the
Semliki Valley, and to western Uganda (Bwamba) and southward to the vicinity
of Luebo in the Kasai; mainly in the tall virgin forest, but ranging out into heavy
gallery forests in the Uelle and Kasai districts of the Congo.

10. C. klaas (Stephens): breeds throughout much of Africa south of the Sahara,
in both savanna and forested regions, from Senegal and Gambia, east to and across
northern Nigeria and the southern Sudan to northwestern Ethiopia and to south-
western Arabia (Asir), and south to Damaraland and the Cape Province; also to
the island of Fernando Poo in the Gulf of Guinea; migratory in the southern part
of its range (roughly south of the Zambesi River), where it is present only from

AVIAN GENUS CHRYSOCOCCYX 111

late October to March or early April; partly or irregularly migratory in parts of
equatorial eastern Africa. The species has been divided into three races, as follows:

C. klaas klaas (Stephens) : range includes all of that given for the species, except
southwestern Arabia, and the coastal belt of the Juba River area of southern
Somalia.

C. klaas arabicus (Bates): southwestern Arabia (Asar, near Faifa, Asir) ; validity
of this race is uncertain and will remain so until further material becomes available.

C. klaas somereni (Chapin): the Juba River area of southern Somalia, possibly
the adjacent northeast corner of Kenya.

11. C. cupreus (Shaw): breeds throughout much of sub-Saharan Africa, chiefly
in evergreen forest but also in dense scrub country, avoiding arid regions and
areas over 8000 feet in altitude, from Senegal, east across upper Guinea to the
southern Sudan to Ethiopia, south to the islands in the Gulf of Guinea (Fernando
Poo, Principe, and Saéo Tomé), to Gabon, and Angola, the Rhodesias, and to
Transvaal, Natal, and the eastern part of Cape Province; migratory in the south-
ern part of its range, where present only in the breeding season, late October to
late March. The species has been divided into four races, the status of two of
which have been matters of uncertainty, as follows:

C. cupreus cupreus (Shaw): from Senegal and Gambia to the Sudan and east
to Ethiopia.

C. cupreus intermedius (Hartlaub): from Cameroon east across the Congo and
Uganda to western Kenya and south to southern Angola and the Zambesi valley
(Mozambique).

C. cupreus sharpei (van Someren): South Africa, especially the eastern part;
winters to the north, but winter range uncertain.

C. cupreus insularum: the islands of the Gulf of Guinea (Sido Tomé and
Principe).

12. C. caprius (Boddaert): breeds throughout most of Africa south of the
Sahara in wooded country and in bushy areas, but not in treeless grasslands or
desert areas, occurs from sea level to about 7000 feet, from Senegal, and the
countries of upper Guinea east to Ethiopia, and south to Cape Province; also
in the islands of Zanzibar, and Mafia on the east coast, and to Fernando Poo in
the Gulf of Guinea; one record from southwestern Arabia (Aden); definitely
migratory south of the Zambesi, where it occurs mainly during the breeding
season, September to April.

From an evolutionary standpoint, the ranges of the present dozen species, with
their 32 more or less distinct races, are of interest in that they reveal more numer-
ous and more extensive areas of sympatry for two or more of the species than
they do areas of intrageneric allopatry. Inasmuch as it is now well established that
speciation and subspeciation are attended in their incipient stages by geographic
isolation, it becomes necessary to postulate considerable subsequent movement
of the various species to account for their present distribution. Thus, we find
malayanus sympatric with zanthorhynchus in the Malay Peninsula (nominate
races of both), in Borneo (C. malayanus aheneus and typical C. zanthorhynchus),
and in the Philippines—at least in Basilan (typical C. malayanus and C. xanthor-
hynchus amethystinus). In southern Australia three species of the genus occur
together to some extent, although partly separated ecologically (C. lucidus
plagosus, C. basalis, and C. osculans); in Africa klaas, cupreus, and caprius are
extensively sympatric, as are also flavigularis, klaas, and cupreus in a more
restricted area.

The still meager data suggest altitudinal allopatry for the two Papuan species,
meyerit and ruficollis, although there may be some overlapping. Allopatry is
clearly indicated for typical C. lucidus in New Zealand and for two of its races

112 U.S. NATIONAL MUSEUM BULLETIN 265

layardi in New Caledonia, New Hebrides, and the Loyalty Islands and harterti
on Rennell and Bellona Islands. The two Asiatic species, maculatus and xantho-
rhynchus, appear to be ecologically and altitudinally largely allopatric, but not
rigidly so (canthorhynchus has a range that extends far beyond that of maculatus
to the east, encompassing areas as distant as Borneo and the Philippines, but
this is something beyond the contiguous allopatry the two species show in south-
ern Asia). The breeding range of osculans implies an extensive area of allopatry
in spite of its southern sympatry with basalis and lucidus plagosus.

In view of the fact that the point of origin, geographically and phylogenetically,
is only inferential in all the 12 species of the group, the only safe conclusion that
may be drawn from their current dispersal is that the several species each went
their own way with no discernible repetition of any generic pattern. The variety
of their geographic dispersal is a telling, though commonplace, commentary on
the opportunistic aspect of evolutionary history.

When one says that each species of Chrysococcyx has gone its own way, this
does not imply any incipient, directive “way” peculiar to each. This becomes
clear when the morphological characters of the geographic races of any of the
polytypic species of the genus are examined. Thus, to take but one instance, the
variations in the distribution of rufescent coloration in the rectrices of some of
the subspecies of malayanus are not selectively ‘‘adaptive’’; they are not characters
that help to make their bearers more or less fitted for the particular places in
which they live. If these characters were plotted on a map they would show no
progressive, rectilinear, or orthogenetic correspondence with the geographic,
spatial relations of the races. The emergence of these slight differences as constantly
recurring phenotypes is merely the result of each population’s having had to
utilize the fragment of the total gene pool of the species available to it. The
possibility exists that these external characters, while diagnostic in the museum
sense, are not selectively important in themselves but that they may be the
outward manifestations of genes that have some adaptive value. This is, ad-
mittedly, beyond the capability of present evidence to prove or to disprove, but
the thought should be kept in mind. The ‘‘way”’ of each species is, not what it
“set out to do or to be, but what has happened to it.”

The high incidence of sympatry in the glossy cuckoos causes one to ask if these
birds have not yet achieved their final, biologically “perfected” stage, especially
since in many instances (plagosus, basalis, and osculans; klaas and caprius) they
are partly homoxenic (sharing the same hosts), even if they show trends toward
alloxenia (using different hosts). If their geographical and ecological sympatry
were accompanied by highly developed and rigidly regulated alloxenia, these
coexisting species of Chrysococcyx would be, as far as their breeding is concerned,
distinctively separated, even though their hosts were sympatric. Such a con-
dition does obtain in some avian arthropod ectoparasites, as was shown by Clay
(1949), and such reproductive differentiation would in itself suffice to counteract
the Gauseian principle that two or more kinds of related animals with identical
or very similar ecological requirements are not able to coexist indefinitely because
one of them will prove more efficient than the other and thus will displace the
latter. The glossy cuckoos are possibly still on the way toward the eventual
circumvention of this situation.

On the other side of the picture, it appears that in all these cases of sympatric
species of glossy cuckoos the forms involved have complete specific independence.
So far as I have been able to learn (and I have examined several thousands of
specimens in all), no instances of hybridization have been found between any
of them. Furthermore, I know of no observations of mixed courtship behavior,
although there often is no ecological or other habitat isolation to prevent it.

AVIAN GENUS CHRYSOCOCCYX bs

This is especially significant in the case of plagosus and basalis, as these species
are superficially fairly similar, and it points to the existence of very effective
isolating mechanisms. In the absence of personal field experience with these two
Australian cuckoos, I cannot evaluate accurately the potential ethological barriers
from the published accounts of their vocalisms, posturings, and so forth, but it
may be assumed that it is here that the restriction of random mating is controlled.
Mayr (1963, pp. 95-107) has brought together from many groups of animals data
which show that differences in behavior which may seem slight to human eyes
may be all important in this respect. He concluded that, if one were to estimate
the relative importance of the various isolating mechanisms, behavioral isolation
would head the list.

Cuckoos as a family appear to be remarkably free from hybridization. In her
1958 compilation of known avian hybrids A. P. Gray listed none for any members
of the family. Subsequently Parkes (1965, pp. 94-95) has reported only one
instance of crossing between two species of terrestrial, sedentary coucals, Centropus
viridis and Centropus bengalensis, in Luzon. The absence of any such records
in the other, more arboreal and more active cuckoos, suggests that specific differ-
ences in appearance, vocalisms, and behavior are constantly effective in their
role of isolating mechanisms.

2. The plumages of Chrysococcyx flavigularis

Although this report is not intended to include detailed plumage descriptions
of the well-known species of glossy cuckoos, in this case it may be useful to have
such an inclusion. The following description is based on that of Reichenow
(1902, p. 100), with modifications due to other material seen and with the addition
of Chapin’s notes (1939, pp. 199-201).

Adult male: upper parts glossy bronze to copper-red, according to Reichenow
and Shelley, but dark, glossy bronze-green in the material I have examined
personally; the two median rectrices dark purplish coppery color, darkest on the
middle portion and at the end, the next pair similar on the inner web but yellowish-
white to white on the outer web, except for a coppery-bronze band near the tip
and also on the basal portion of the feathers, with a white tip; the remaining
rectrices white with interrupted dusky bronze subterminal bands and similar
bases, the outermost rectrix almost entirely white; remiges dark brown, barred
incompletely with whitish or pale buffy on the inner webs; chin and middle of
throat and breast bright yellow, bordered with bright, dark glossy green (like the
top and sides of the head); posterior underparts of body and the under wing
coverts pale cinnamon-buff with narrow, somewhat wavy bars of dusky earth-
brown, some of these bars with a faint bronze sheen, the interspaces between
the bars a little more than one and a half times as broad as the bars; under tail
coverts similar but the dusky bars more widely separated; iris dull chrome-yellow,
edge of eyelids light yellowish-green; bill dull greenish-yellow, base of the maxilla
blackish; feet duli yeilowish-green, claws black; wing 91.5—100; tail 70-80; culmen
from base 17-18; tarsus 14 mm.

Adult female: top of head dark bronze-green with fine, whitish transverse
vermiculations on the forehead, sides of crown, and sides of occiput—occasionally
these fine markings extend right across the crown and occiput and hind neck;
nape, back, scapulars, upper wing coverts, rump, and upper tail coverts dark
glossy bronze-green, sometimes with a slightly lighter, more golden, tinge; the
lesser and median upper wing coverts with narrow cinnamon tips and widely
spaced narrow bars of the same; remiges fuscous, with a faint bronze sheen,

114 U.S. NATIONAL MUSEUM BULLETIN 265

especially on the outer web, and, in some, probably younger, adults, with in-
complete bars of pale cinnamon on the outer webs, and always with incomplete
wedge-shaped bars of the same on the inner margins of the basal two-thirds of
the inner webs; median rectrices dusky blackish-brown with a faint coppery
sheen and narrowly tipped with pale brownish-white; the next pair similar on the
inner web, but banded on the outer web with pale cinnamon; the next pair with
the inner web blackish-brown banded with cinnamon and with the outer webs
largely white with a blackish-brown subterminal band immediately before the
white tip; the two outermost pairs wholly white with some incomplete dark-
brown bars on the inner web; lores, sides of face, auriculars, sides of neck, and
entire underparts from chin to vent pale buffy-white to white, finely marked
with somewhat wavy, narrow bars of dusky-brown, some with a faint bronze
sheen; iris gray to pale yellowish-brown; eyelids greenish; bill dark brownish-
black above, dull yellow below; wing 92-97; tail 58-64; culmen from the base
15.5-17; tarsus 12.5-13.5 mm.

Juvenal (males only seen, but sexes probably alike): similar to adult female,
but with the feathers of the forehead, crown, occiput, nape, scapulars, and upper
wing coverts with cross bars; underparts as in females but slightly more brownish
in ground color; iris grayish-white to brownish-white; bill dark brown on maxilla,
yellow on mandible; feet yellow.

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1957. An annotated check list of the birds of Eritrea, pt. 2. Ibis, vol. 99,
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AVIAN GENUS CHRYSOCOCCYX 127

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128 U.S. NATIONAL MUSEUM BULLETIN 265

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Index

abbotti, Trichastoma, 50
Acanthiza, 38
chrysorrhoa, 42, 44, 46, 47, 49, 61,
70, 88, 93, 100
ewingii, 43, 47
hamiltoni, 47
inornata, 43
iredalei, 47
lineata, 42, 43, 47
magnus, 44
nana, 42, 43, 47
pusilla, 42, 43, 46, 47, 61
reguloides. 42, 43, 46, 47
robustirostris, 47
uropygialis, 43, 46, 47
Acanthornis superciliosus,44, 48
tenuirostris, 44, 48
Acrocephalus australis, 44, 47
adustus, Alseonax, 53
Aegintha temporalis, 44, 48
Aethopyga, 39
gouldiae, 50
siparaja, 50, 51
siparaja seheriae, 70, 71
afer, Cinnyris, 52, 53
affinis, Melithreptes, 48
Prinia subflava, 59, 89
agile, Dicaeum, 51
aguimp, Motacilla, 52, 58
aheneus, Chrysococcyx malayanus, 62,
109, 111
albicilla, Mohoua, 41
albifrons, Amblyospiza, 56, 59, 74
Chrysococcyx malayanus, 40, 62,
68, 109
Epthianura, 43, 46
albofrontata, Gerygone, 41, 62
albonotatus, Euplectes, 59
Alcippe nipalensis, 50
alloxenia, 39, 103
Alseonax adustus, 53
minimus, 52, 53
amabilis, Malurus, 40, 47
Amaurodryas vittata, 43
Amblyospiza albifrons, 56, 59, 74
amethystina, Chalcomitra, 52, 53, 58,
91

amethystinus, Chrysococcyx xanthor-
hynchus, 32, 50, 110, 111
Amytornis striatus, 47
anonyma, Cisticola, 53
Anthornis melanura, 41
Anthreptes collaris, 54, 72
Anthus novaeseelandiae, 58
Apalis flavida, 52, 53
thoracica, 52, 53
Aphelocephala castaneiventris, 47
leucopsis, 47, 48
nigrocincta, 47, 61
arabicus, Chrysococcyx klaas, 33, 111
Arachnothera, 39
longirostris, 50, 51, 71, 78
ardens, Euplectes, 59
Artamus cinereus, 44
personatus, 44
assimilis, Malurus, 47, 49
atricapillus, Melithreptes, 48
aureoflavus, Ploceus subaureus, 59
aurifrons, Epthianura, 43, 46
australis, Acrocephalus, 44, 47
Eopsaltria, 43, 46
Miro, 41
baglafecht, Ploceus, 59
bakeri, Cuculus canorus, 60
bangueyensis, Chrysococcyx xanthor-
hynchus, 32, 50, 110
barbatus, Pyenonotus, 53-55, 73, 78
basalis, Chrysococcyx, 1, 4, 7-9, 21-25,
31, 34, 37-39, 42, 46, 61-63, 67,
69, 77-83, 85, 88, 89, 93, 96, 104,
105, 110-112
Batis capensis, 52, 53, 72
molitor, 53
bengalensis, Centropus, 113
bichenovii, Steganopleura, 48
bohndorffi, Ploceus cucullatus, 60
bojeri, Ploceus, 59
brachyura, Camaroptera, 58
Bradornis microrhynchus, 58
pallidus, 58
Bradypterus luteoventris, 50
brevicaudata, Camaroptera, 53
brevirostris, Melithreptes, 44, 48
Smicrornis, 42, 43, 47
129

130 U.S. NATIONAL MUSEUM BULLETIN 265

brunneipectus, Gerygone, 40
brunneus, Pyrrholaemus, 39, 49, 70
cabanisi, Emberiza, 54
Cacomantis, 4, 5, 6, 12, 20, 21, 36-38,
68, 80, 87, 96, 102, 103
castaneiventris, 37
flabelliformis, 102
merulinus, 37
pyrrhophanus, 37
sonnerati, 17
variolosus,
cafer, Cuculus, 20
caffra, Cossypha, 58
Calamanthus campestris, 44, 47
fuliginosus, 47, 61
isabellinus, 49
Calamocichla leptorhyncha, 58
rufescens, 53
callainus, Malurus, 44, 47
Camaroptera brachyura, 58
brevicaudata, 53
campestris, Calamanthus, 44, 47
canorus, Cuculus, 20, 39, 68, 78, 80, 84,
90, 93, 102, 107
cantans, Cisticola, 53
capensis, Batis, 52, 53, 72
EKuplectes, 59
Fringillaria, 59
Motacilla, 52, 55, 58
Ploceus, 57-59, 74, 96
capitalis, Ploceus melanocephalus, 60
caprius, Chrysococcyx, 1, 4, 7, 15, 16,
19-25, 27, 32-39, 51, 52, 56-60,
64, 67, 68, 71, 74-77, 87-89, 91,
93, 96-98, 100, 101, 104, 106,
107,211
Lampromorpha, 5
cardinalis, Quelea, 59
Carduelis carduelis, 39, 48
cassidix, Meliphaga, 44
castanea, Diaphorophyia, 53
castaneiceps, Seicercus, 50
castaneiventris, Aphelocephala, 47
Cacomantis, 37
castaneofuscus, Ploceus nigerrimus, 60
castanops, Ploceus, 59
castanotis, Taeniopygia, 48
caudatus, Lamprotornis, 53
cauta, Hylacola, 47, 49, 61, 70
Centropus bengalensis, 113
viridis, 113
Cercococcyx, 12, 37
Cercomela familiaris, 58

cerviniventris, Poecilodryas, 43
Cettia fortipes, 50
Chalcites, 4
lucidus, 5
Chalcococcyx, 5
Chalcomitra amethystina, 52, 53, 58, 91
olivacea, 53, 55, 56, 58, 73, 78
rufescens, 53
senegalensis, 52, 53 ,55, 56, 58, 72,
73
veroxii, 54
chalybeus, Cinnyris, 53
Chloris chloris, 48
chloropygius, Cinnyris, 56, 58
Chrysococcyx
atavistic behavior, 1
brood parasitism, 36 ff
courtship behavior, 34
eggs, interval between, 85-87
eggs, mode of laying, 81-85
eggs, morphism, 2, 66-81
eggs, number, 87
eggs, removal by adults, 87-90
eviction of nest-mates by nestlings,
96-98
fledgling feeding by adults, 98-103
geographic dispersals of, 7, 25
geographic range of, 3
host selection, 36-39
host specificity, 60-66
hosts (see under each species)
host-parasite nestling relations, 91—
95
mandibular oviposition
evidence for, 82-83
evolutionary significance of, 84
migratory behavior, 2, 32, 33, 34
phylogenetic relations, 3
plumages
hepatic, 26
sex dimorphism, 2
ventral barring, 12
psychobiological adaptiveness, 84
species and races of, 109-112
sympatry and allopatry, 112-113
Chrysococcyx basalis, 1, 4, 7-9, 21-25,
31, 34, 37-39, 42, 46, 61-63, 67,
69, 77-85, 88, 89, 93, 96, 104,
105, 110-112
hosts, 44-49
caprius, 1, 4, 7, 15, 16, 19-27, 32-
39, 51, 52, 56-60, 64, 67, 68, 71,

INDEX

Chrysococcyx caprius—Continued
74-77, 87-89, 91, 93, 96-98, 100,
101, 104, 106, 107, 111

egg mimicry, 64
egg morphism, 74-77
hosts, 56-60
cupreus, 4, 5, 15, 18-20, 23-27,
32-34, 37, 38, 54-56, 64, 67, 68,
77-79, 83, 88, 89, 96, 98, 104,
106, 111
egg mimicry, 64
hosts, 54-56
cupreus cupreus, 111
cupreus insularum, 111
cupreus intermedius, 111
cupreus sharpei, 111
flavigularis, 4, 6, 12, 15-19, 23-25,
32, 3a, 67, LO4, 1106; 109; 112
klaas, 1, 4, 7, 15-27, 32-89, 51-55,
64, 67, 68, 77, 83, 87-89, 93,
96-100, 104, 106, 107, 110
egg mimicry, 64
eggs, 72
hosts, 51-54
klaas arabicus, 33, 111
klaas klaas, 111
klaas somereni, 33, 111
lucidus, 4, 8-11, 21-26, 29, 34-37,
39, 41-44, 61, 62, 67, 69, 77, 88,
89, 96, 98, 100, 104, 105, 107, 109
egg morphism, 69
host specificity, 62
hosts, 41-44
lucidus harterti, 9, 15, 21, 27, 29,
31, 62, 110, 112
lucidus layardi, 9, 15, 27, 29-31, 62,
106, 110, 112
hosts, 41
lucidus lucidus, 7, 26, 27, 29-381,
62, 69, 106, 109
hosts, 41
lucidus plagosus, 1, 7, 9, 11, 15,
21, 22, 27, 29-31, 37, 38, 62, 63,
68, 69, 78, 80, 85, 88, 110-112
hosts, 42-44
maculatus, 4, 11-17, 20, 22-25, 31,
32, 38, 39, 49, 50, 64, 67, 71,
77-79, 85, 88, 96, 104-106, 110
egg mimicry, 64
eggs, 71
hosts, 49-50
seasonal plumage, 14

131

Chrysococcyx—Continued

malayanus, 1, 4, 8-11, 21-24, 29,
37, 39, 40, 62, 67-68, 72, 77,
89, 104, 105, 107, 109

egg morphism, 68
host specificity, 62
hosts, 40

malayanus aheneus, 62, 109, 111

malayanus albifrons, 40, 62, 68, 109

malayanus crassirostris, 28, 29, 62,
109

malayanus jungei, 62, 109

malayanus malayanus, 40, 62, 68,
69, 109, 111

hosts, 40

malayanus minutillus, 9, 10, 21,

28, 29, 40, 62, 69, 109
hosts, 40

malayanus misoriensis, 109

malayanus poecilurus, 9, 21, 40,
62, 68, 69, 109

hosts, 40

malayanus rufomerus, 10, 28, 29,
62, 109

malayanus russatus, 10, 26, 40, 62,
68, 69, 81, 82, 109

host, 40

malayanus salvadorii, 62, 109

meyerii, 4, 6, 10, 11, 13, 20, 21,
23-25, 31, 104, 105, 110, 111

osculans, 1, 4, 20, 22—25, 31, 37,
39, 48, 49, 63, 67-70, 72, 77-79,
85, 89, 96, 104-106, 110-112

egg morphism, 70
host specificity, 63
hosts, 48-49

ruficollis, 4, 6, 10, 11, 20, 22-25,
31, 104, 110, 111

xanthorhynchus, 4, 11-15, 17, 20,
22-26, 31, 32, 38, 39, 49, 50,
64, 67; 71, (1=79; 85, “88, 89;
96, 104-106, 110, 112

eggs, 71
hosts, 50

xanthorhynchus amethystinus, 32,
50; 110, 111

xanthorhynchus bangueyensis, 32,
50, 110

xanthorhynchus xanthorhynchus,
PLO; 11:

chrysops, Meliphaga, 44, 48
chrysoptera, Neositta, 44, 47

132

chrysorrhoa, Acanthiza, 42, 44, 46, 47,
49, 61, 70, 88, 93, 100
Chthonicola sagittata, 39, 44, 47, 49,
63, 68, 70, 78, 91

cincta, Poephila, 48
cinereifrons, Heteromyias, 40, 43, 46
cinereus, Artamus, 44
Cinnyricinclus, 15
Cinnyris afer, 52, 53

chalybeus, 53

chloropygius, 56, 58

cupreus, 53

reichenowi, 56

venustus, 52, 53
Cisticola anonyma, 53

cantans, 53

erythrops, 53, 58

exilis, 44, 47

fulvicapilla, 53

juncidis, 50

natalensis, 53

robusta, 53, 58

ruficeps, 58

woosnami, 53
Clamator, 1, 12, 28, 37, 84, 87, 97, 102

glandarius, 37

jacobinus, 68
Climacteris picumnus, 44
Coccyzus, 12
coelebs, Fringilla, 39, 41
Colius, colius, 57, 58, 74
collaris, Anthreptes, 54, 72

Lanius, 58

Ploceus cucullatus, 60
Colluricincla harmonica, 43
correiae, Gerygone flavolateralis, 62
Cossypha caffra, 58
craspedopterus, Euplectes hordeaceus,

60
crassirostris, Chrysococcyx malayanus,
28, 29, 62, 109

crocatus, Ploceus ocularis, 59
cubla, Dryoscopus, 54, 55
cucullata, Melanodryas, 43
Petroica, 46
cucullatus, Ploceus, 54, 56-59, 76
Cuculus, 1, 4-6, 12, 36-38, 84, 87, 96,
98, 103
cafer, 20
canorus, 39, 68, 78, 80, 84, 90, 93,
102, 107
canorus bakeri, 60
canorus canorus, 20

U.S. NATIONAL MUSEUM BULLETIN 265

Cuculus—Continued
canorus gularis, 20, 101
canorus telephonus, 60
micropterus, 60, 102
optatus, 60, 102
pallidus, 20, 34, 37, 100, 102, 105
poliocephalus, 79
saturatus, 79
solitarius, 20
cuneata, Geopelia, 46
cupreus, Chrysococcyx, 4, 5, 15, 18-20,
23-27, 32-38, 54-56, 64, 67, 68,
77-79, 83, 88, 89, 96, 98, 104,
106, 111
Cinnyris, 53
cyaneus, Malurus, 37, 42, 44, 45, 47,
49, 61, 63, 83, 85
cyaniventer, Tesia, 50
cyanoleuca, Myiagra, 43, 46
Cyanomitra verticalis, 53, 93
cyanotis, Malurus, 61
Cyrtostomus frenatus, 40, 44, 48, 82
Dessonornis humeralis, 58
Diaphorophyia castanea, 53
Dicaeum agile, 51
hirundinaceum, 48
dimidiatus, Ploceus melanocephalus, 60
Dioptrornis fischeri, 55
dohrni, Horizorhinus, 55
domesticus, Passer, 39, 41, 44, 48, 54, 58
Dryoscopus cubla, 54, 55
gambensis, 55
duboisi, Ploceus melanocephalus, 60
Emberiza cabanisi, 54
flaviventris, 58, 59
eminibey, Passer, 59
Eopsaltria australis, 438, 46
epilepidota, Napothera, 50
Epthianura albifrons, 43, 46
aurifrons, 43, 46
tricolor, 43, 46
Eremomela icteropygialis, 53
erythroceria, Nectarinia, 52-56, 58, 73,
91
erythrops, Cisticola, 53, 58
EKudynamis, 37, 97, 103
scolopacea, 102
Euplectes albonotatus, 59
ardens, 59
capensis, 59
gierowii, 59
hordeaceus, 56, 58, 59
hordeaceus craspedopterus, 60

INDEX

Euplectes—Continued
hordeaceus hordeaceus, 60
nigroventris, 54, 59
orix, 51, 54, 56-59, 64, 65, 74-76,

78, 86, 89, 92, 97

ewingii, Acanthiza, 43, 47

exilis, Cisticola, 44, 47

familiaris, Cercomela, 58

famosa, Nectarinia, 53

fasciata, Gliciphila, 40, 48

fasciogularis, Meliphaga, 40, 48

ficedulinus, Zosterops, 55

fischeri, Dioptrornis, 55

flabellifera, Rhipidura, 41

flabelliformis, Cacomantis, 102

flava, Meliphaga, 48

flavicans, Prinia, 58, 74

flavida, Apalis, 52, 53
Gerygone, 40, 43

flavigularis, Chrysococcyx, 4, 6, 12,

15-19, 23-25, 32, 33, 67, 104,
106, 110, 113

flaviventris, Emberiza, 58, 59

flavolateralis, Gerygone, 41, 62

fortipes, Cettia, 50

frenatus, Cyrtostomus, 40, 44, 48, 82

Fringilla coelebs, 39, 41

Fringillaria capensis, 59

frontalis, Sericornis, 47

fuliginosa, Rhipidura, 43, 46

fuliginosus, Calamanthus, 47, 61

fulvicapilla, Cisticola, 53

fusca, Gerygone, 43, 47, 61

gambensis, Dryoscopus, 55

Geopelia cuneata, 46

Gerygone, 26, 27
albofrontata, 41, 62
brunneipectus, 40
flavida, 40, 43
flavolateralis, 41, 62
flavolateralis correiae, 62
fusca, 43, 47, 61
igata, 41, 62, 79, 96, 98
levigaster, 47
magnirostris, 40, 42, 43, 46, 62, 82
mouki, 43, 47
olivacea, 40, 42, 43, 46
palpebrosa, 40, 47
richmondi, 42, 43, 46
sulphurea, 40, 62, 68

gierowii, Euplectes, 59

glandarius, Clamator, 37

133

Gliciphila albifrons, 48
fasciata, 40, 48
indistineta, 48
melanops, 44, 48
goodenovii, Petroica, 43, 46, 63, 82
gouldi, Zosterops, 44, 48
gouldiae, Aethopyga, 50
gramineus, Megalurus, 44, 47
graueri, Ploceus cucullatus, 60
Prinia subflava, 59
griseovirescens, Zosterops, 55
griseus, Passer, 59
gularis, Cuculus canorus, 20, 101
guttatus, Zonaeginthus, 48
hamiltoni, Acanthiza, 47
harmonica, Colluricinela, 43
harterti, Chrysococcyx lucidus, 9, 15,
21, 27, 29, 31, 62, 110, 112
Heteromyias cinereifrons, 40, 43, 46
heuglini, Ploceus, 59
Hierococcyx, 102
hirundinaceum, Dicaeum, 48
Hirundo neoxena, 43, 46
homoxenia, 39, 103
hordeaceus, Euplectes, 56, 58, 59
Horizorhinus dohrni, 55
humeralis, Dessonornis, 58
hybridization in cuckoos, 113
Hylacola cauta, 47, 49, 61, 70
pyrrhopygia, 47, 49
Hylochelidon nigricans, 43
iagoensis, Passer, 54, 58
icteropygialis, Eremomela, 53
igata, Gerygone, 41, 62, 79, 96, 98
immutabilis, Prinia subflava, 59
Indicator, 87
indistincta, Gliciphila, 48
inornata, Acanthiza, 43
inquieta, Seisura, 46
insularum, Chrysococcyx cupreus, 111
intermedius, Chrysococcyx cupreus, 111
Ploceus, 51, 52, 54, 58, 59, 74, 76
iredalei, Acanthiza, 47
isabellinus, Calamanthus, 49
jacksoni, Ploceus, 59
jacobinus, Clamator, 68
jamesoni, Ploceus xanthops, 75
jardinei, Turdoides, 53, 58
juncidis, Cisticola, 50
jungei, Chrysococcyx malayanus, 62,
109
kilimensis, Nectarinia, 53, 56, 58, 93

134

klaas, Chrysococcyx, 1, 4, 7, 15-27,
32-39, 51-55, 64, 67, 68, 72, 77,
83, 87-89, 93, 96-100, 104, 106,
107, 110
Lampromorpha, 5
Lalage sueurii, 43
lamberti, Malurus, 47, 61, 82
Lamprococcyx, 4, 5
Lampromorpha caprius, 5
klaas, 5
Lamprotornis, 15
caudatus, 53
Lanius collaris, 58
larvatus, Oriolus, 55, 58
lateralis, Zosterops, 41, 44, 48
lathami, Sericornis, 44, 47, 49
layardi, Chrysococcyx lucidus, 9, 15, 27,
29-31, 62, 106, 110, 112
hosts, 41
leptorhyncha, Calamocichla, 58
leuconotus, Malurus, 44, 45, 47
leucophaea, Microeca, 43, 46
Speirops, 55
leucophrys, Rhipidura, 43, 46
leucopsis, Aphelocephala, 47, 48
leucopterus, Malurus, 47, 61
leucotis, Meliphaga, 44, 48
levigaster, Gerygone, 47
lewinii, Meliphaga, 40, 48
lineata, Acanthiza, 42, 43, 47
longirostris, Arachnothera, 50, 51, 71,
78
lucidus, Chalcites, 5
Chrysococcyx, 4, 8-11, 21-26, 29,
34-37, 39, 41-44, 61, 62, 67, 69,
77, 88, 89, 96, 98, 100, 104, 105,
107, 109
luteoventris, Bradypterus, 50
maculata, Sericornis, 37
maculatus, Chrysococcyx, 4, 11-17, 20,
22-25, 31, 32, 38, 39, 49, 50, 64,
67, 71, 77-79, 85, 88, 96, 104-106,
110
egg mimicry, 64
eggs, 71
hosts, 49, 50
seasonal plumage, 14
Sericornis, 44, 47, 49
maculosa, Prinia, 58
magnirostris, Gerygone, 40, 42, 43, 46,
62, 82
Sericornis, 44, 47

U.S. NATIONAL MUSEUM BULLETIN

265

magnus, Acanthiza, 44
mahali, Plocepasser, 54, 58
malachurus, Stipiturus, 44, 47
malayanus, Chrysococcyx, 1, 4, 8-11,
21-24, 29, 37, 39, 40, 62, 67, 68,
72, 77, 89, 104, 105, 107, 109
egg morphism, 68
host specificity, 62
hosts, 40
Malimbus malimbicus, 56
rubriceps, 54, 58, 59
Malurus, 38
amabilis, 40, 47
assimilis, 47, 49
callainus, 44, 47
cyaneus, 37, 42, 44, 45, 47, 49, 61,
63, 83, 85
cyanotis, 61
lamberti, 47, 61, 82
leuconotus, 44, 45, 47
leucopterus, 47, 61
melanocephalus, 40, 44, 47
melanotus, 47
splendens, 44, 47
Megalurus gramineus, 44, 47
melanocephala, Petroica, 41
melanocephalus, Malurus, 40, 44, 47
Ploceus, 59
Melanodryas cucullata, 43
melanops, Gliciphila, 44, 48
melanotus, Malurus, 47
melanura, Anthornis, 41
melanurus, Passer, 56-58, 64, 74-76,
78, 90, 95
Meliornis niger, 48
novaehollandiae, 42, 44, 48
Meliphaga cassidix, 44
chrysops, 44, 48
fasciogularis, 40, 48
flava, 48
leucotis, 44, 48
lewinii, 40, 48
ornata, 44, 48
penicillata, 44, 48
Melithreptus affinis, 48
atricapillus, 48
brevirostris, 44, 48
merula, Turdus, 39, 41
merulinus, Cacomantis, 37
meyerii, Chrysococcyx, 4, 6, 10, 11, 13,
20-25, 31, 104, 105, 110, 111
Microeca leucophaea, 438, 46

INDEX

micropterus, Cuculus, 60, 102
microrhynchus, Bradornis, 58
minimus, Alseonax, 52, 53
minutillus, Chrysococcyx malayanus, 9,
10, 21, 28, 29, 40, 62, 69, 109
Miro australis, 41
Misocalius, 4, 5
misoriensis, Chrysococcyx malayanus,
109
Mohoua albicilla, 41
molitor, Batis, 53
Molothrus, 87, 97
Monarcha trivirgata, 43
Motacilla aguimp, 52, 58
capensis, 52, 55, 58
capensis capensis, 59
capensis wellsi, 59
mouki, Gerygone, 43, 47
multicolor, Petroica, 43, 46
Myiagra cyanoleuca, 43, 46
rubecula, 43
Myioparus plumbeus, 53
Myzomela nigra, 44, 48
sanguinolenta, 48
nana, Acanthiza, 42, 43, 47
Napothera epilepidota, 50
natalensis, Cisticola, 53
Nectarinia erythroceria, 52, 53, 54, 56,
58, 73, 91
famosa, 53
kilimensis, 53, 56, 58, 93
pulchellus, 53
tacazze, 53
Neochalcites, 5
Neochmia phaeton, 44
Neositta chrysoptera, 44, 47
pileata, 47
neoxena, Hirundo, 43, 46
niger, Meliornis, 48
nigerrimus, Ploceus, 58, 59, 65, 76
nigra, Myzomela, 44, 48
nigricans, Hylochelidon, 43
nigriceps, Ploceus cucullatus, 60
Stachyris, 50
nigrifrons, Ploceus velatus, 60
nigrocincta, Aphelocephala, 47, 61
nigroventris, Euplectes, 54, 59
nipalensis, Alcippe, 50
novaehollandiae, Meliornis, 42, 44, 48
Scythrops, 102
novaeseelandiae, Anthus, 58
ocularis, Ploceus, 56, 58, 59, 74

135

olivacea, Chalcomitra, 53, 55, 56, 58,
73, 78
Gerygone, 40, 42, 43, 46
olivaceus, Ploceus capensis, 74, 75, 85,
91
Turdus, 58
optatus, Cuculus, 60, 102
Oriolus larvatus, 55, 58
orix, Euplectes, 51, 54, 56-59, 64, 65,
74-78, 86, 89, 92, 97
ornata, Meliphaga, 44, 48
Orthotomus sutorius, 50
osculans, Chrysococcyx, 1, 4, 20, 22-25,
31, 37, 39, 48-49, 63, 67-70, 72,
77-79, 85, 89, 96, 104-106, 110-
1?
egg morphism, 70
host specificity, 63
hosts, 48-49
Pachycoccyx, 37
pallidus, Bradornis, 58
Cuculus, 20, 34, 37, 100, 102, 105
palpebrosa, Gerygone, 40, 47
Pardalotus punctatus, 44, 48
striatus, 42, 44
Parisoma subcaeruleum, 53, 55, 58, 74
Passer domesticus, 39, 41, 44, 48, 54,
58
eminibey, 59
griseus, 59
lagoensis, 54, 58
melanurus, 56-58, 64, 74-76, 78,
90, 95
melanurus melanurus, 59
melanurus vicinus, 59
peltata, Platysteira, 55
pelzelni, Ploceus, 59, 76
penicillata, Meliphaga, 44, 48
Penthoceryx, 102
personatus, Artamus, 44
Petroica cucullata, 46
goodenovii, 438, 46, 63, 82
melanocephala, 41
multicolor, 43, 46
phoenicea, 43, 46
rhodinogaster, 43
rosea, 46
Petronia superciliaris, 59
phaeton, Neochmia, 44
phoenicea, Petroica, 43, 46
Pholidornis rushiae, 56
Phylidonyris pyrrhoptera, 48
Phylloscopus reguloides, 50

136

picumnus, Climacteris, 44
pileata, Neositta, 47
plagosus, Chrysococcyx lucidus, 1, 7,
Or tila 21, 22275 29a, «de,
38, 42-44, 62, 63, 68, 69, 78, 80,
85, 88, 104, 111, 112
hosts, 42—44
Platysteira peltata, 55
Plocepasser mahali, 54, 58
Ploceus baglafecht, 59
bojeri, 59
capensis, 57-59, 74, 96
capensis olivaceus, 74, 75, 85, 91
castanops, 59
cucullatus, 54, 56-59, 76
cucullatus bohndorffi, 60
cucullatus collaris, 60
cucullatus cucullatus, 60
cucullatus graueri, 60
cucullatus nigriceps, 60
cucullatus spilonotus, 60
heuglini, 59
intermedius, 51, 52, 54, 58, 59, 74,
76
jacksoni, 59
melanocephalus, 59
melanocephalus capitalis, 60
melanocephalus dimidiatus, 60
melanocephalus duboisi, 60
nigerrimus, 58, 59, 65, 76
nigerrimus castaneofuscus, 60
nigerrimus nigerrimus, 60
ocularis, 56, 58, 59, 74
ocularis crocatus, 59
ocularis ocularis, 59
ocularis suahelicus, 59
pelzelni, 59, 76
reichenowi, 52, 54-56
rubiginosus, 59
subaureus, 56, 59
subaureus aureoflavus, 59
subaureus subaureus, 59
taeniopterus, 59
tricolor, 59
velatus, 51, 54, 56-59, 65, 74-76,
78, 87, 89, 95, 97
velatus nigrifrons, 60
velatus velatus, 60
xanthops, 56, 59
xanthops jamesoni, 75
xanthopterus, 59
plumbeus, Myioparus, 53

U.S. NATIONAL MUSEUM BULLETIN 265

Poecilodryas cerviniventris, 43
poecilurus, Chrysococcyx malayanus, 9,
21, 40, 62, 68, 69, 109
Poephila cincta, 48
poliocephalus, Cuculus, 79
Prinia flavicans, 58, 74
maculosa, 58
subflava, 51-53, 55, 57, 58, 64, 72
subflava affinis, 59, 89
subflava graueri, 59
subflava immutabilis, 59
pulchellus, Nectarinia, 53
punctatus, Pardalotus, 44, 48
pusilla, Acanthiza, 42, 43, 46, 47, 61
Pycnonotus barbatus, 53-55, 73, 78
Pyrrholaemus brunneus, 39, 49, 70
pyrrhophanus, Cacomantis, 37
pyrrhoptera, Phylidonyris, 48
pyrrhopygia, Hylacola, 47, 49
Quelea cardinalis, 59
reguloides, Acanthiza, 42, 43, 46, 47
Phylloscopus, 50
reichenowi, Cinnyris, 56
Ploceus, 52, 54-56
Rhipidura, 26, 27
flabellifera, 41
fuliginosa, 43, 46
leucophrys, 43, 46
rufifrons, 46
setosa, 40, 46
rhodinogaster, Petroica, 43
richmondi, Gerygone, 42, 43, 46
robusta, Cisticola, 53, 58
robustirostris, Acanthiza, 47
rosea, Petroica, 46
rubecula, Myiagra, 43
rubescens, Chalecomitra, 53
rubiginosus, Ploceus, 59
rubriceps, Malimbus, 54, 58, 59
rufescens, Calamocichla, 53
Sylvietta, 53
ruficeps, Cisticola, 58
Stachyris, 50
ruficollis, Chrysococcyx, 4, 6, 10, 11,
20, 22-25, 31, 104, 110, 111
rufifrons, Rhipidura, 46
rufiventer, Terpsiphone, 55
rufomerus, Chrysococcyx malayanus,
10, 28, 29, 62, 109
rushiae, Pholidornis, 56
russatus, Chrysococcyx malayanus, 10,
26, 40, 62, 68, 69, 81, 82, 109

INDEX

sagittata, Chthonicola, 39, 44, 47, 49,
63, 68, 70, 78, 91
salvadorii, Chrysococcyx malayanus,
62, 109
sanguinolenta, Myzomela, 48
saturatus, Cuculus, 79
Saxicola torquata, 53
scolopacea, Eudynamis, 102
Scythrops, 12, 103
novaehollandiae, 102
seheriae, Aethopyga siparaja, 70, 71
Seicercus castaneiceps, 50
xanthoschistus, 50
Seisura inquieta, 46
senegalensis, Chalcomitra, 52, 53, 55,
56, 58, 72, 73
Zosterops, 53
Sericornis frontalis, 47
lathami, 44, 47, 49
maculata, 37
maculatus, 44, 47, 49
magnirostris, 44, 47
setosa, Rhipidura, 40, 46
sharpei, Chrysococcyx cupreus, 111
siparaja, Aethopyga, 51, 51
Smicrornis brevirostris, 42, 43, 47
solitarius, Cuculus, 20
somereni, Chrysococcyx klaas, 33, 111
sonnerati, Cacomantis, 17
Speirops leucophaea, 55
spilonotus, Ploceus cucullatus, 60
splendens, Malurus, 44, 47
Stachyris nigriceps, 50
ruficeps, 50
Steganopleura bichenovii, 48
Stipiturus malachurus, 44, 47
striatus, Amytornis, 47
Pardalotus, 42, 44
suahelicus, Ploceus ocularis, 59
subaureus, Ploceus, 56, 59
subcaeruleum, Parisoma, 53, 55, 58, 74
subflava, Prinia, 51-53, 55, 57, 58, 64, 72
sueurii, Lalage, 43
sulphurea, Gerygone, 40, 62, 68
superciliaris, Petronia, 59
superciliosus, Acanthornis, 44, 48
Surniculus, 102
sutorius, Orthotomus, 50
Sylvietta rufescens, 53
tacazze, Nectarinia, 53

137

taenipoterus, Ploceus, 59
Taeniopygia castanotis, 48
taitensis, Urodynamis, 26, 37, 79
telephonus, Cuculus canorus, 60
temporalis, Aegintha, 44, 48
tenuirostris, Acanthornis, 44, 48
Terpsiphone rufiventer, 55
viridis, 52-55, 58
Tesia cyaniventer, 50
thoracica, Apalis, 52, 53
torquata, Saxicola, 53
Trichastoma abbotti, 50
tricolor, Epthianura, 43, 46
Ploceus, 59
trivirgata, Monarcha, 43
Turdoides jardinei, 53, 58
Turdus merula, 39, 41
olivaceus, 58
Urodynamis taitensis, 26, 37, 79
uropygialis, Acanthiza, 43, 46, 47
variolosus, Cacomantis, 37
velatus, Ploceus, 5, 54, 56-59, 65,
74-78, 87, 89, 95, 97
venustus, Cinnyris, 52, 53
veroxii, Chalcomitra, 54
verticalis, Cyanomitra, 53, 93
vicinus, Passer melanurus, 59
Vidua, 87, 97
virens, Zosterops, 55
viridis, Centropus, 113
Terpsiphone, 52-55, 58
vittata, Amaurodryas, 43
wellsi, Motacilla capensis, 59
woosnami, Cisticola, 53
xanthops, Ploceus, 56, 59
xanthopterus, Ploceus, 59
xanthorhynchus, Chrysococcyx, 4, 11-
15, 17, 20, 22-26, 31, 32, 38, 39,
49, 50, 64, 67, 71, 77-79, 85, 88,
89, 96, 104-106, 110, 111
eggs, 71
hosts, 50
xanthoschistus, Seicercus, 50
Zonaeginthus guttatus, 48
Zosterops ficedulinus, 55
gouldi, 44, 48
griseovirescens, 55
lateralis, 41, 44, 48
senegalensis, 53
virens, 55

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