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Volume 6, Number 1, 1975

POPULATION FLUCTUATION IN A
YELLOW-HEADED BLACKBIRD MARSH

ROGER J. LEDERER, Department of Biological Sciences, California State Uni-
versity, Chico, California 95926

WALTER S. MAZEN, Department of Biological Sciences, California State Uni-
versity, Chico, California 95926 (present address; 945 J Street #339, Davis, Cali-
fornia 95616)

PETER J. METROPULOS, Department of Biological Sciences, California State
University, Chico, California 95926

The breeding ecology of the Yellow-headed Blackbird (Xanthoce-
phalus xanthocephalus) has been well studied by Willson and Orians
(1963) and Willson (1966) and the information presented in this study
essentially agrees with their findings. In our study the number of nests,
active and inactive, found in 1973 was tenfold greater than that found
in 1972 and in 1974 it was fifty percent greater than in 1973 . We would
like to propose explanations for these different rates of increase in nest
building in three consecutive years in the same habitat.

STUDY AREA AND METHODS

The area studied is a marsh 300 m north of the Eagle Lake Field
Station on the east shore of Eagle Lake, Lassen County, California. The
area immediately surrounding the marsh is flat with sandy, alkali soil.
Basin Sage Brush {Artemisia tridentata), rabbitbrush {Chrysothamnus
nauseosus) and Downy Brome {Bromus tectorum) are the most abund-
ant plants surrounding the marsh for at least 100 m in all directions.
Bullrush (Scirpus sp.) and rushes (Juncus sp.) are the dominant emergent
vegetation. The marsh has been in existence for only eight years. It
was created by a rising water table (R. Ediger pers. comm.) and has been
increasing in size each year.

Observations on the Yellow-headed Blackbird began in May, but most
of the field work was done during the periods of 18 June to 24 July
1972 (Walk 1972), 20 June to 20 July 1973 and 20 June to 22 July

Western Birds 6: 1-6, 1975 1

YELLOW-HEADED BLACKBIRD

1974. The behavior of the birds was observed almost daily during these
periods.

We marked each nest in the study area with a numbered tag and
visited them every two days subsequently. We banded the nestlings im-
mediately after hatching or as soon afterward as possible. Body weights
of the nestlings and lengths of their longest primary were taken at each
visit.

We made line transects at 25 m intervals to measure the abundance
and density of the emergent vegetation.

TERRITORIES AND NESTS

Male birds begin to arrive in late April and early May, and almost
immediately begin to establish territories. The males are polygynous,
having 2-5 females, the number being related to the size, location and
vegetational features of the territory (Willson 1966). The total adult
population was estimated at 25 birds in 1972, 85 in 1973 and 83 in

The females built their nests in rushes where there were 108-180
reeds per mC Eight to 70 reed stalks were ineorporated into each nest.
Nests supported by juncus required at least five times as many individ-
ual plants as those supported by the larger, stronger Scirpus. Table 2
lists additional information on nest strueture.

We did not measure territory size in 1972, but they ranged in area
from 40.4 to 101 m* in 1973 and 50 to 150 m* in 1974. Theseare
small territories for this species (Willson 1966, Fautin 1940) but are
comparable to those found on Willson’s study at Ramer Lake in 1963.
She explains that the dense population and smaller territories might be
possible because the major food was found elsewhere. This was apparent-
ly true in this study since the males were regularly seen flying to Eagle
Lake’s shoreline to feed, a distance of 200 m to 1 km or more.

Table 1. Yellow-headed Blackbird nesting data. Eagle Lake Field Station, Cali-
fornia.

1974.

1972

1973

29

67

96

3.0

47

1974

19

no

129

Number of active nests.

Number of inactive nests
Total nests found
Average clutch size
Number of young fledging
Mortality

Average number of young fledged per nest

Unknown

Unknown

Unknown

8

8

3.0

0

38%

1.6

32

37 %

2.7

1.7

2

YELLOW-HEADED BLACKBIRD

Table 2. Yellow-headed Blackbird nest structure, Eagle Lake Field Station, Cali-
fornia.

1973

1974

Average nest height

21 cm

17 cm

Average nest diameter (outside)

15 cm

14 cm

Average nest depth

5 cm

5 cm

Average height above water (to bottom of nest)

38 cm

30 cm

Average distance between nests

5.1 m

8.3 m

CLUTCH SIZE

Table 1 gives nesting data for the years 1972-1974. Only 8 nests,
all active, were found in 1972. In 1973 and 1974 many more nests
were found, but most were inactive. Only 29 were active in 1973 and
19 in 1974 although respective totals of 96 and 129 completed nests
were located; the remainder were not used. The average clutch size
was approximately 3 for all years. This appears to be somewhat small
compared to other studies (Roberts 1909, Fautin 1940, Willson 1966).
In 1972 all young of the small population of 8 nests were fledged by
July but most nests were quite active at this same time in 1973 and
1974.

GROW'JH RATES AND MORTALITY

The young weighed 5-8 g at birth and averaged a weight increase of 5
grams/day. Willson (1966) found that males gain weight at a somewhat
faster rate (7.1 g/day) than females (4.6 g/day). We found that the
rate of elongation of the 10th primary was slower than the rate of weight
gain; the nestlings added an average of 5 mm in primary length per day.

The incubation period ranged from 12-13 days and the period spent
in the nest by young was 10-12 days. Table 1 shows nest success and
mortality data. Known mortalities were due to drowning, abandon-
ment and starvation, strangulation in reeds, and failure to hatch. Other
eggs and young disappeared due to unknown reasons, possibly preda-
tion by Raccoons {Procyon lotor) (Walk 1972). The weather was very
mild during the entire study in 1972 and 1973 but there were 3 days of
heavy rains in 1974 which apparently caused several nests to topple.

DISCUSSION

What caused the dramatic increase in nests and adult birds from 1972
to 1973? The only factor that was considerably different between the

3

YELLOW-HEADED BLACKBIRD

two years was the water depth of the marsh. The average depth of the
marsh in 1973 was 0.78 m, while in 1972 it was over 1 m. This decrease
in depth and increase in amount of emergent vegetation due to succes-
sional processes resulted in a much more widespread and denser growth
of the emergent vegetation, both Scirpus and Juncus. This growth pro-
vided many more nest sites than were available in 1972. The popula-
tions of the other birds (Killdeer, Charadrius vociferus; American Avo-
CGt, Recurvirostra americana; Spotted Sandpiper, Actitis macularia -, Wil-
son’s Phalarope, Steganopus tricolor-. Black Tern, Chlidonias niger-, and
Blue-winged Teal, Anas discors) which nested in or on the edges of the
marsh were similar for the two years, so interspecific competition for
nest sites as an explanation seems unlikely. Interspecific competition
for food also seems improbable due to different feeding habits.

In 1974 the marsh was about 5.3 hectares in size, versus about 4
hectares in 1972 and 1973. This increase was undoubtedly due to the
rise in the water table and increased rainfall (P. Maslin pers. comm.).
In addition a “late” spring in 1974 (pers. obs.) retarded plant growth.

The increased average water depth (1.1 m) and delayed vegetation
growth made it necessary for the birds to utilize thinner, shorter stalks
of Scirpus and Juncus than would usually be present. Most of the nests
were built in Juncus which grew in shallower water than Scirpus, much
of which was too short to support nests at the beginning of the nesting
period. The weaker Juncus collapsed in many instances (37% of all
nests found). So although the marsh was larger, the increased water
depth in part delayed plant growth, making fewer suitable nest sites
available. Even though there were more nests built in 1974 than 1973,
only 19 were active in 1974 versus 29 in 1973.

Many of these additional nests could have been due to nesting at-
tempts which failed or frustration nests (nests built but unused). The
nesting area was visited several times before the onset of the study and
no eggs or incubation behavior was noted so it appears that most of
these nests were frustration nests.

The similarity of population sizes of adult birds in 1973 (85) and
1974 (83) indicates that the marsh habitat may have temporarily reached
its capacity to support a breeding blackbird population. Perhaps with
more favorable weather and consequently faster plant growth and more
nesting sites, more adults could have nested in the marsh in 1974. The
larger territory size in 1974 indicates poorer quality territories than in
1973.

CONCLUSIONS

It appears that the enormous increase in size of the blackbird colony
from 1972 to 1973 was likely due to the increasing plant colonization
4

YELLOW-HEADED BLACKBIRD

of the marsh by natural succession, thereby providing additional nesting
sites. Other possibilities are: 1) more birds discovering the suitable habi-
tat; and/or 2) previous nesters and their young returning to the marsh.
From 1973 to 1974 a smaller increase was noted, possibly due to the
following: 1) the potential of the marsh in terms of number of nesting
sites was being fulfilled, 2) high water and cooler weather delayed plant
maturation, thereby producing fewer nest sites, and 3) many nests were
built but not used.

The number of blackbirds nesting in any colony is greatly influenced,
if not controlled by, the availability of potential nest sites. The number
of nest sites is influenced by water depth, weather and habitat size.
Cool weather and high water at the onset of breeding season delays
plant maturation, allowing fewer sites. Warmer weather and shallower
water provide more sites at the appropriate time.

Since the study has only been made for three consecutive years and
the weather has been somewhat different each year, no definite pat-
terns have emerged. There is another large colony of Yellow-headed
Blackbirds on the opposite side of Eagle Lake (Crase and DeHaven
1972). It is possible that population sizes in these two colonies is in-
terdependent, i.e., the density of the population in one marsh may be
dependent on the suitability of the other for nesting. Additionally,
the number of adults arriving in either may be influenced by the degree
of previous breeding success in the other. A simultaneous study of both
marsh habitats over several years would prove interesting.

ACKNOWLEDGMENTS

We would like to thank Drs. Thomas L. Rodgers and Mary F. Willson
for their helpful comments on the manuscript. This work was support-
ed by the Eagle Lake Field Station of California State University, Chico.

LITERATURE CITED

Crase, F, T. and R. W. DeHaven. 1972. Current breeding status of the Yellow-
headed Blackbird in California. Calif. Birds 3:39-42.

Fautin, R. W. 1940. The establishment and maintenance of territories by the
Yellow-headed Blackbird in Utah. Great Basin Nat. 2:75-91.

Roberts, T. S. 1909. A study of a breeding colony of Yellow-headed Blackbirds
Auk 24:371-389.

Walk, L. 1972, Vertebrate observations at a marsh. Eagle Lake Field Station,
California State University, Chico. Unpublished.

5

YELLOW-HEADED BLACKBIRD

Willson, M. F. 1966. Breeding ecology of the Yellow-headed Blackbird. Ecol.
Monogr. 36;51-77.

Willson, M. F. and G. H. Orians. 1963. Comparative ecology of Redwinged and
Yellow-headed Blackbirds during the breeding season. Proc. XVI Int. Congr.
Zool. 3:342-346.

Sketch by Franz Cilensek

6

STATUS OF THE YELLOW-BILLED LOON
{GAVIA ADAMSiDm THE WESTERN UNITED
STATES AND MEXICO

J. V. REMSEN, JR., Department of Zoology, University of California, Berkeley,
California 94720

LAURENCE C. BINFORD, California Academy of Sciences, Golden Gate Park,
San Francisco, California 94118

Current knowledge of the breeding range, dispersal routes, and win-
tering range of the Yellow-billed Loon (Gavia adamsii) is summarized by
Burn and Mather (1974). However, neither these authors nor the AOU
Check-list (1957) cite acceptable records for Mexico or the contiguous
western United States. The purpose of this paper is to enumerate and
analyze the 52 records that have been obtained from this area during
the last 19 years. The problems of distinguishing this species from the
Common Loon (Gavia immer) in the field and hand are discussed by
Binford and Remsen (1974) and Burn and Mather (1974).

GEOGRAPHIC DISTRIBUTION

The 52 records that we consider acceptable through August 1974 are
distributed as follows: Washington, 26 (0 represented by museum speci-
mens, 5 others by photographs, and 21 by sight records only); Oregon,
3 (0, 1 , 2); California, 20 (3, 3, 14); Nevada, 1 (0, 0, 1); and Baja Cali-
fornia, 2 (1, 0, 1). These records are listed in Appendix A. Additional
published records for which substantiating details are either inadequate
or not available are presented in Appendix B.

The vast majority (84.6%) of records between the British Columbia
border and northern Baja California are from two regions: central Cali-
fornia and the area embracing Puget Sound and the Straits of Georgia
and Juan de Fuca, Washington (see Summaries of Distribution Within
States). This rather spotty distribution probably is largely a result of
uneven coverage by observers. We have examined the supposed adamsii
specimen from Colorado and find that it is a typical example of G. im-
mer (see Appendix B), leaving the Nevada sighting as the only inland oc-
currence for the contiguous United States. The record from near San
Felipe, Baja California is the southernmost for the species in North
America (Simon and Simon 1974).

Western Birds 6:7-20, 1975

7

YELLOW-BILLED LOON

SEASONAL DISTRIBUTION

Forty-eight of the 52 records are for the period 20 October-4 May.
The remaining four records, one each for Washington, Oregon, Califor-
nia, and Baja California, extend from 14 June through 15 July. Because
the other three species of loons summer in small numbers along the
coast (Grinnell and Miller 1944, McCaskie and DeBenedictis 1966, Jew-
ett et al. 195 3), the occurrence of Yellow-billed Loons in summer is
not surprising.

The 46 non-summer records from Washington, Oregon, and Califor-
nia are plotted in a seasonal chart (Figure 1). A comparison of dates
on which birds were first discovereddiscloses the following trend: 66.7%
of Washington-Oregon birds arrived between 2 November and 17 Janu-
ary and the remaining 33.3% between 7 March and 22 April, with none
in the intervening seven weeks. The average arrival dates for fall and
spring were 9 December and 22 March. Only three of eighteen (16.7%)
Washington birds and no Oregon birds overwintered. In California, on
the other hand, only 21.1% of the birds were discovered prior to 29
December, 73.7% from 29 December to 26 January, one bird in mid-
February, and none in March or April. The six-day period 21-26 Janu-
ary alone produced 47.4% of all California discoveries. The average
“fall” arrival date was 3 January.

The most likely explanation for this difference in seasonal pattern
between the two areas is that fall migrants usually do not overwinter in
Washington and Oregon but by late January have moved farther south
into California (and Baja California), where they arrive sometimes as
early as 20 October but principally in late January. Beginning in late
February and extending into early May, the wintering birds leave Cali-
fornia and move north again, migrating through coastal Washington and
Oregon primarily in March. All three of the Washington wintering birds
apparently left during this period, one in late February and two in April.
Wayne C. Weber (pers. comm.) of Vancouver states that in March and
early April a similar spring migration takes place in southwestern British
Columbia.

Although not supported by direct evidence, such as movements of
marked individuals, this explanation seems to be the most plausible one
to fit the available data. Mr. Weber, however, feels that more birds
winter in the Puget Sound-Straits of Georgia area than in California, and
that the discrepancy in winter abundance between Washington and Cali-
fornia might be due to the greater number of active birders in the latter
state. There are, in fact, a number of February records for southwestern
British Columbia, and almost certainly the paucity of records from Ore-
gon and coastal southern Washington reflects the low numbers of ob-
servers in those areas. We believe, however, that the number of observers
affects only the absolute number of records, whereas the relative pro-

8

YELLOW-BILLED LOON

portion of records in the different time periods reflects a true pattern
in seasonal distribution.

The only Yellow-billed Loon discovered in California after 26 Janu-
ary was on 18 February in Humboldt County, at least 180 miles north
of the localities that have produced all other California records. This
bird, which was last seen on 7 March, might have been on its way north

Figure 1. Seasonal distribution of the Yellow-billed Loon in California and the
Washington-Oregon area. Each line represents the period of occurrence, plotted
in three-day intervals, for one of the 46 birds recorded from October to May.
See text for discussion and Appendix A for specific data. Compare the Washington-
Oregon area to California and note the following: the earlier arrival, on the average,
in Washington-Oregon; in January, the sudden cessation of arrivals and exodus of
temporary fall visitants (each labeled “a” in figure) in Washington-Oregon, and
the ensuing increase of arrivals in California; the scarcity of overwintering birds
(b) in Washington-Oregon, and the failure of California birds discovered before
mid-January to overwinter; the discrete cluster of spring transient migrants in
Washington-Oregon, the paucity thereof (c) in California, and the nearly simul-
taneous departure of most overwintering birds (d) from both areas (generally
earlier in California).

9

YELLOW-BILLED LOON

after wintering farther south and would have been expected to pass
through Humboldt County about that time— slightly earlier than the
first northbound birds are detected in Washington and Oregon (early
March). Thus the Humboldt record probably supports our interpreta-
tion of seasonal distribution. [The only other Humboldt County bird,
present from 23 February to 7 March 1975 (D. Erickson pers. comm.),
beyond the cut-off date for records analyzed in this paper, also fits this
pattern.]

The discovery of two birds in Baja California, despite the scarcity of
observers there, suggests that south of central California Yellow-billed
Loons may be more regular than supposed. Furthermore, California
birds arriving prior to 17 January are not known to have remained for
more than 1 1 days and thus may represent transient migrants that win-
ter in Baja California. This is further suggested by the earliness of the
only winter-period record for Baja, 24 November, which is 15 days ear-
lier than the average arrival date for Washington-Oregon. Surprisingly,
however, not a single bird has been recorded in southern California, a
very thoroughly birded area, nor have any returning spring transients
been recorded in central California.

The only Nevada bird was found at Lake Tahoe on 6 January (1973).
Because this date is only three days beyond the average fall arrival date
for California, and because at this latitude no California bird has com-
menced overwintering prior to 17 January, the Nevada bird seems to
fit the general seasonal pattern as a fall transient migrant.

SUMMARIES OF DISTRIBUTION WITHIN STATES

Washington: rare but regular transient migrant (2 Nov. -26 Jan.; 7
Mar. -22 Apr.; average arrival dates, 9 Dec. and 22 Mar.); casual winter
resident (three records); casual in summer (one record). All but one
record are from the area embracing Puget Sound and the Straits of
Georgia and Juan de Fuca, but this is almost certainly a result of the
concentration of observers there.

Oregon: two March records; casual in summer (one record). The
paucity of records is probably the result of the scarcity of observers
in coastal areas. We predict that more thorough coverage will demon-
strate a distribution extending along the entire coast and a seasonal
status similar to that in Washington.

California: very rare but regular winter resident (20 Oct. -4 May; aver-
age “fall” arrival date, 3 Jan.); records concentrated in late January;
birds arriving before 17 January are not known to winter and thus may
be transient migrants; casual in summer (one record). All records, ex-
cept one from Humboldt Bay, are for central California from Sonoma
County to Monterey County.

10

YELLOW-BILLED LOON

Baja California: casual in fall (one record) and summer (one record).
Both records are from extreme northern Baja, one each from the Paci-
fic Ocean and the Gulf of California.

Nevada: accidental (one January record for Lake Tahoe that may
represent a “fall” transient migrant).

COMPARISON BETWEEN YEARS

Prior to the winter of 1967-68, only three Yellow-billed Loons had
been noted in the area with which we are concerned: one each in the
winters of 1956-57, 1963-64, and 1964-65, all in Washington. In the
seven winters from 1967-68 to 1973-74, however, 45 birds were record-
ed (Table 1), with an additional four summer occurrences. Some ob-
servers (e.g. Small 1974) feel that the species had been previously over-
looked and that the abrupt surge in records in recent years is only a
function of the increase in number of observers and their sudden alert-
ness, after the original discoveries, to the possible presence and field
marks of the species. Others, including ourselves, feel that this recent
increase does in fact reflect a true change in status for the following
reasons: (1) observers in the Pacific Northwest have always looked for
this species (J, B. Crowell, Jr. pers. comm.); (2) the increase in records
in both California and Washington began in the same winter, 1967-68;
and (3) this species probably could not have been overlooked in the
past in such thoroughly covered California localities as Monterey harbor.
Moss Landing, Tomales Bay, and Bodega Bay. This question, however,
cannot be answered with certainty at this time.

Table 1. Annual occurrence of the Yellow-billed Loon in the western United States
and Mexico. Numbers of records are listed by locality for seven winter periods
(October-May), 1967-1974.

WINTER

WASH.

ORE.

CALIF.

NEV.

BAJA

CALIF.

TOTAL

1967-68

2

-

2

-

-

4

1968-69

1

2

5

-

1

9

1969-70

1

-

1

-

-

2

1970-71

4

-

4

-

-

8

1971-72

2

-

2

-

-

4

1972-73

5

-

3

1

-

9

1973-74

7

-

2

-

-

9

11

YELLOW-BILLED LOON

A comparison of the total number of records for each of the last
seven winter periods (Table 1) suggests this species has “good winters”
and “bad winters.” Although perhaps real, this trend cannot be statis-
tically tested with such low sample sizes.

HABITAT PREFERENCES

Habitat utilization by the Yellow-billed Loon in the western United
States and Mexico is indicated in Table 2. This species shows a prefer-
ence for very sheltered waters (58.3% of all observations), such as To-
males Bay and Monterey harbor, and moderately sheltered waters (3 1.2%)
such as Puget Sound, Monterey Bay, and the Gulf of California. This
distribution is similar to that shown by Common and Red-throated
{Gavia stellata) loons but contrasts with that of the Arctic Loon (G.
arctica), which in winter is primarily a deep-water species that often
feeds in rafts one to five miles offshore (pers. obs.).

Although we have no quantitative data available, our impression is
that the Yellow-billed Loon prefers shallower water than the Common
Loon. The same trend has been noted by W. C, Weber (pers. comm.) in
the Vancouver area, but not by observers in Bellingham, Washington (T.
R. Wahl pers. comm.). Within a pair of closely related species, the ten-
dency for the one with the more upturned bill to be found in shallower
water is also seen in the Red-throated and Arctic loons and the Eared

Table 2. Habitat preferences of the Yellow-billed Loon in the western United
States and Mexico. Numbers of records are listed by locality for each habitat.

BAJA

HABITAT WASH. ORE. CALIF. NEV. CALIF. TOTAL % TOTAL

Ocean more than

one mile offshore 1

Exposed
ocean coast

Moderately shel-
tered waters
(sounds, gulfs, and
exposed bays) 12

Very sheltered
waters (unexposed
bays, river mouths,
estuaries and

harbors) 8 3

1

1

2

17

1 2 4.2

1 2.1

1 15 31.2

28 58.3

2 4.2

Lakes

1

YELLOW-BILLED LOON

and Horned grebes (Storer 1960, Binford and Remsen pers. obs.). Pre-
sumably the upturned bill facilitates benthic feeding, i.e. scraping an
item from a substrate (Jehl 1970). Spring (1971) shows that in con-
trast to the Common Murre {Uria aalge), which feeds in open water, the
Thick-billed Murre (U. lomvia) is primarily a bottom feeder and has the
more upturned lower mandible.

SEX RATIO

Of the eight adamsii specimens taken in Britain (Burn and Mather
1974), one in Baja California (Jehl 1970), and three in California, all
are females. Because the probability of drawing 12 straight females by
chance from a population with an equal sex ratio is virtually zero, the
preponderance of females must be real. Two possible explanations— that
the sex ratio in the total population very strongly favors females or that
the mortality rate in these southern areas is higher for females— seem
to us very unlikely. Rather, we postulate that females winter, or at
least wander, farther south than males. Page et al. (1972) have demon-
strated that in the Western Sandpiper {Calidris mauri) females outnum-
ber males at the southern extremities of the species’ range.

MORTALITY

In California three out of the 20 (15%) Yellow-billed Loons were
seen alive but later found dead, and several others appeared to be sick.
Burn and Mather (1974) report that 20 of the 39 (5 1.3%) British records
were of dead or dying birds. Such rates of unhealthiness seem much
higher than would be considered normal and indicate that conditions in
these southern waters are not conducive to survival. Support for this
speculation is provided by the only available datum on cause of death.
The first specimen for California was autopsied by Dr. Bernice Eddie
of the George William Hooper Foundation, University of California Med-
ical Center, San Francisco, and found to have died of aspergillosis {As-
pergillus sp.), a respiratory disease especially prevalent among water birds.
This is apparently the first report of aspergillosis in the Yellow-billed
Loon (see O’Meara and Witter 1971). Perhaps there is a higher inci-
dence of, or greater susceptibility to, aspergillosis or other diseases in
the warmer, more polluted southern areas than in the colder, cleaner
arctic regions that this species normally inhabits. If such is the case,
disease could be a major factor in determining the southern limits of
the ranges of this loon and certain other arctic water birds. Similar
high rates of mortality are indicated by Yadon (1970) for the Thick-

13

YELLOW-BILLED LOON

billed Murre and by Grinnell and Miller (1944) for the Horned Puffin
(Fratercula corniculata) and Parakeet Auklet {Cyclorrhynchus psittacula\
all of which are only stragglers as far south as California. However, the
distinct movement of spring migrant Yellow-billed Loons through Ore-
gon, Washington, and southwestern British Columbia indicates that win-
tering to the south is not always fatal.

SUMMARY

Fifty-two Yellow-billed Loon records, including four specimens, have
been obtained from the western United States and Mexico since 1956
(Washington, 26; Oregon, 3; California, 20; Nevada, 1; and Baja Califor-
nia, 2). Records extend from 20 October to 4 May, with an additional
four in summer. This species is a very rare but regular winter resident
in central California but seems to be primarily a transient migrant in
Washington, Oregon, and northern California. The only Colorado record
proves to be a Common Loon, leaving the Nevada sighting as the only
inland record south- of Canada. The San Felipe, Baja California record
is the southernmost for the species in North America. The surge of
records beginning in the winter of 1967-68 suggests that the Yellow-
billed Loon is extending its range southward. Most records (89.5%)
are for moderately to very sheltered waters. That all twelve specimens
from California, Baja California, and Britain are females suggests that
females winter or wander farther south than males. The abnormally
high rates of mortality and sickness, including one fatal case of asper-
gillosis, suggest that disease may be a proximate factor delimiting the
southern range of this and other arctic water birds.

ACKNOWLEDGMENTS

We wish to express deep gratitude to Terence R. Wahl for providing
unpublished records, correcting dates on previously published Washing-
ton records, classifying the Washington records by habitat, reading an
early draft of the manuscript, and together with Dennis R. Paulson and
David L. Pearson, for supplying photographs of Washington birds. Ste-
phen F. Bailey, John B. Crowell, Jr., Guy McCaskie, J. P. Myers, and
Wayne C. Weber made many useful criticisms of the manuscript. Bruce
Broadbooks, Stanley W. Harris, Guy McCaskie, Robert Russell, and G.
Shumway Suffel kindly sent us loon descriptions from their field notes.
Richard Stallcup supplied data from the files of American Birds (Middle
Pacific Coast Region) and Joseph Morlan brought to our attention cer-

14

YELLOW-BILLED LOON

tain other records. David DeSante generously allowed us to publish his
Nevada record. Betsy Webb, of the Denver Museum of Natural History,
made available the Colorado specimen thought to be a Yellow-billed
Loon.

LITERATURE CITED

American Ornithologists’ Union. 1957. Check-list of North American birds.
Fifth ed. Am. Ornithol. Union, Baltimore, Md.

Bailey, A. M. and F. C. Lincoln. 1954. The Yellow-billed Loon (Cavia adamsii)
in Colorado. Auk 71:203.

Bailey, A. M. and R. J. Niedrach. 1965. Birds of Colorado, vol I. Denver Mus.
Nat. Hist., Colorado.

Baldridge, A. and T. Chandik. 1969. The winter season. Middle Pacific Coast
region. Aud. Field Notes 23:513-5 18.

Baldridge, A. and T. Chandik. 1970. The winter season. Middle Pacific Coast
region. Aud. Field Notes 24:533-537.

Binford, L. C. and J. V. Remsen, Jr. 1974. Identification of the Yellow-billed
Loon {Gavia adamsii). West. Birds 5:111-126.

Boggs, B. and E. Boggs. 1964. Winter season. Northern Pacific Coast region.
Aud. Field Notes 18:379-381.

Burn, D. M. and J. R. Mather. 1974. The White-billed Diver in Britain. British
Birds 67:257-296.

Chandik, T. and A. Baldridge. 1968. Winter season. Middle Pacific Coast region.
Aud. Field Notes 22:472-476.

Chandik, T. and A. Baldridge. 1969. Fall migration. Middle Pacific Coast region.
Aud. Field Notes 23:99-106.

Crowell, J. B., Jr. and H. B. Nehls. 1968. Winter season. Northern Pacific Coast
region. Aud. Field Notes 22:468-472.

Crowell, J. B., Jr. and H. B. Nehls. 1969. The winter season. Northern Pacific
Coast region. Aud. Field Notes 23:508-513.

Crowell, J. B., Jr. and H. B. Nehls. 1970. The winter season. Northern Pacific
Coast region. Aud. Field Notes 24:5 30-5 33.

Crowell, J. B., Jr. and H. B. Nehls. 1971. The winter season. Northern Pacific
Coast region. Am. Birds 25:614-619.

Crowell, J. B., Jr. and H. B. Nehls. 1972a. The winter season. Northern Pacific
Coast region. Am. Birds 26:644-648.

Crowell, J. B., Jr. and H. B. Nehls. 1972b, The nesting season. Northern Pacific
Coast region. Am. Birds 26:893-897.

Crowell, J. B., Jr. and H. B. Nehls. 1973a. The fall migration. Northern Pacific
Coast region. Am. Birds 27:105-110.

Crowell, J. B., Jr. and H. B. Nehls. 1973b. The spring migration. Northern Paci-
fic Coast region. Am, Birds 27:809-812.

Crowell, J. B., Jr. and H. B. Nehls. 1974. The nesting season. Northern Pacific
Coast region. Am. Birds 28:938-943.

DeSante, D., D. A. Gaines and V. Remsen. 1973. The winter season. Middle
Pacific Coast region. Am. Birds 27:656-662.

15

YELLOW-BILLED LOON

DeSante, D, and R. LeValley. 1972a. The winter season. Middle Pacific Coast
region. Am. Birds 26:648-654.

DeSante, D. and R. LeValley. 1972b. The spring migration. Middle Pacific Coast
region. Am. Birds 26:801-807.

DeSante, D. and A. Wang. 1971. The winter season. Middle Pacific Coast region.
Am. Birds 25:619-626.

Grinnell, J. and A. H. Miller. 1944. The distribution of the birds of California.
Pac. Coast Avif. No. 27.

Homem, V. 1971a. Field observations. Gull 53:22.

Homem, V. 1971b. Field observations. Gull 53:33.

Homem, V. 1972a. Field observations. Gull 54:12.

Homem, V. 1972b. Field observations. Gull 54:32.

Homem, V. 1973. Field observations. Gull 55:14.

Jehl, J. R., Jr. 1970. A Mexican specimen of the Yellow-billed Loon. Condor
72:376.

Jewett, S. G., W. P. Taylor, W. T. Shaw and J. W. Aldrich. 1953. Birds of Washing-
ton State. Univ. Washington Press, Seattle.

McCaskie, G. and P. DeBenedictis. 1966. Birds of northern California. Annotat-
ed field list. Golden Gate Audubon Society, Berkeley, California.

McLean, B. A. 1971. The seventy-first Christmas bird count. Western Sonoma
County, Calif. Am. Birds 25:512-513.

O’Meara, D. C. and J. F. Witter. 1971. Pages 153-162 in J. W. Davis, R. C. An-
derson, L. Karstad and D. O. Trainer, eds. Infectious and parasitic diseases
of wild birds. Iowa State Univ. Press, Ames.

Page, G., B. Fearis and R. M. Jurek. 1972. Age and sex composition of Western
Sandpipers on Bolinas Lagoon. Calif. Birds 3:79-86.

Remsen, V. and D. A. Gaines. 1973. The nesting season. Middle Pacific Coast
region. Am. Birds 27:91 1-91 7.

Remsen, V. and D. A. Gaines. 1974. The fall migration. Middle Pacific Coast
region. Am. Birds 28:98-106.

Russell, R., Jr. 1972. The seventy-second Christmas bird count. San Juan Islands,
Wash.-B.C. Am. Birds 26:489.

Schultz, Z. 1970. The occurrence of the Yellow-billed Loon in Washington.
Murrelet 51:23.

Simon, D. and W. F. Simon. 1974. A Yellow-billed Loon in Baja California,
Mexico. West. Birds 5:23.

Small, A. 1974. The birds of California. Winchester Press, New York.

Spring, L. 1971. A comparison of functional and morphological adaptations in
the Common Murre {Uria aalge) and Thick-billed Murre (Uria lomvia). Condor
73:1-27.

Stallcup, R. and R. Greenberg. 1974. The winter season. Middle Pacific Coast
region. Am. Birds 28 :684-691 .

Storer, R. W. I960. Evolution in the diving birds. Proc. XII Intern. Ornith.
Congress, Helsinki, 1958.

Yadon, V. L. 1970. Four Thick-billed Murre records for Monterey Bay. Calif.
Birds 1:107-110.

Yocum, C. F. and S. W. Harris. 1975. Birds of northwestern California. Hum-
boldt State Univ. Bookstore, Areata, California.

16

YELLOW-BILLED LOON

APPENDIX A. Acceptable records of the Yellow-billed Loon from the western
United States and Mexico. Each record is designated according to its supporting
evidence as follows: (1) MS = museum specimen; (2) P = photograph but no
specimen; and (3) SR = sight record for which there are written details but no
photograph or specimen. Each of these designations is modified as follows: (a)
evidence examined by one or both of us; or (b) evidence not examined by us but
by a professional ornithologist, Regional Editor oi American Birds Audu-

bon Field Notes), or Terence R. Wahl of Bellingham, Washington, who has field
experience with this species. Records are listed chronologieally by county. For
birds recorded on more than one day, only the first and last dates are given; for
specimens, the last date given is the day of collection.

WASHINGTON

Clallam Co. P(a) 27 Mar. -3 Apr. 1971 (not 26 Mar. as in Crowell and Nehls
1971); Ediz Hook; photographed by D. R. Paulson and D. L. Pearson (Wahl pers.
comm.). SR(b) 14 Jul. 1974; Neah Bay (Crowell and Nehls 1974); seen by S.
Wilson and J. Wingfield.

Grays Harbor Co. SR(b) 17 Jan. 1971; Westport (Crowell and Nehls 1971);
seen by G. Hoge and W. Hoge.

Jefferson Co. SR(b) 6 Dec. 1969; Hood’s Canal (Crowell and Nehls 1970);
seen by B. Evans, P. Evans, D. Lindstrom, J. Rathfelder, R. Rathfelder et al.
(Wahl pers. comm.). SR(b) 22 Apr. 1973; Admiralty Inlet, east of Port Town-
send (Crowell and Nehls 1973b); seen by A. Benedict. SR(b) 18 Nov. 1973 ; Hood’s
Canal;^een by B, Evans and P. Evans (Wahl pers. comm.).

King Co. SR(a) 23 Dec. 1956; Seward Park, Seattle; seen by Z. Schultz et
al. (Schultz 1970); although the details published by Schultz are not in them-
selves convincing, her reputation as a careful and eompetent field observer and
verbal descriptions to T. R. Wahl and others have led most field observers in
Washington to regard this as the first state record.

Mason Co. SR(b) 16 Mar. 1974; Shelton; seen by G. Hoge and W. Hoge
(Crowell pers. comm.).

San Juan Co. SR(a) 18 Dec. 1971; near Stuart Is., San Juan Islands; seen by
R. Russell (Russell 1972 and pers. comm.). P(b) 17 Dec. 1972-early Jan. 1973;
Friday Harbor; seen by J. Duemmel and D. Heinemann and photographed by the
latter (Wahl pers. comm.).

Skagit Co. SR(b) 28 Mar. 1969; Deception Pass (Crowell and Nehls 1969);
seen by D. S. Payne. SR(b) 17 Dec. 1972-6 Apr. 1973; seen by E. Hunn, N.
Lavers et al. (Crowell and Nehls 1973b, Wahl pers. comm.). SR(b) 7-8 Mar.
1973; Samish Is.; seen by N. Lavers and C. Lavers (Wahl pers. comm.). SR(b)
31 Mar. 1974; Samish Is.; seen by N. Lavers (Wahl pers. comm.).

Thurston Co. SR(b) 24-30 Nov. 1973; Eld Inlet, 10 miles north of Olympia;
seen by B. Estes, G. Hoge and W. Hoge (Crowell pers. comm.).

Whatcom Co. Sr(b) 21 Dec. 1963-26 Jan. 1964; Point Roberts (Boggs and
Boggs 1964); seen by Mr. and Mrs. W. H. Hesse et al. SR(b) 15 Nov. 1964; Point
Roberts; seen by T. R. Wahl (pers. comm.). SR(b) 14-15 Jan. 1968 (not 12-13
Jan. as given by Schultz 1970); Birch Bay; seen by Z. Schultz, E. Grahlfs, E.
Stopps, D. S. Payne and T. R. Wahl; presumed by Crowell and Nehls (1968) to be
same bird as the one seen 9-30 Mar. 1968 but probably not (Wahl pers. comm.).
P(a) 9-30 Mar. 1968; Bellingham; found and photographed by D. S. Payne (Wahl
pers. comm); see cover photo Aud. Field Notes 22(3) 1968. P(b) 31 Dec. 1970-

17

YELLOW-BILLED LOON

22 Feb. 1971; South Bellingham; found by J. Duemmel and photographed by T.
R. Wahl (pets. comm.). SR(b) 3 Jan. 1971; Sandy Point; seen by E, W. Stiles
(Wahl pers. comm.). SR(b) 2 Jan. 1972; Bellingham (Crowell and Nehls 1972a);
seen by T. R. Wahl. SR(b) 2 Nov. 1972; Blaine (Crowell and Nehls 1973a); seen
by D. R. Paulson. P(a) 3 Nov. 1973-1 Jan. 1974; South Bellingham; found and
photographed by T. R. Wahl (pers. comm.). SR(a) 3 Nov. 1973-12 Apr. 1974;
Point Roberts; found by R. Phillips and also seen by D. Heinemann, W. H. Hesse,

B. A. MacDonald, D. L. Pearson, A. Small, T. R. Wahl, W. C. Weber et al. (Wahl
pers. comm., Weber pers. comm.). SR(b) 17 Nov. 1973-19 Jan. 1974; South
Bellingham; different individual from that found on 3 Nov. 1973; found by T. R.
Wahl and seen by many others (Wahl pers. comm.).

CALIFORNIA

Alameda Co. SR(a) 3 Dec. 1972; Alameda beach; seen by J. Morlan and E.
Roemer (Homem 1972a, Morlan pers. comm.). P(a) 26 Jan. 1973 ; Berkeley Pier
(DeSante et al. 1973); found and photographed by C. Maynard.

Humboldt Co. SR(a) 18 Feb.-7 Mar. 1973; Humboldt Bay (DeSante et al.
1973); found by R. LeValley and also seen by D. Erickson, S. W. Harris, T.
Schulenberg et al.

Marin Co. MS(a) 1-11 Dec. 1967 (not 12 Dec. as published by Chandik and
Baldridge 1968); Inverness, Tomales Bay; found by G. Brady and seen by many
until 11 Dec. when found dead by G. Miller (pers. comm.); California Academy
of Sciences No. 65864; female. SR(b) 1 Jan. 1968; Pierce Point, Tomales Bay
(Chandik and Baldridge 1968); seen by R. Stallcup. SR(b) 25 Jan. 1971; Inver-
ness, Tomales Bay (DeSanteand Wang 1971); seen by R. Stallcup.

Monterey Co. MS(b) 29 Dec. 1968-1 Jan. 1969; Monterey harbor (Baldridge
and Chandik 1969); found by R. Greenberg and R. Griswold and also seen by L.

C. Binford, T. Chandik et al.; Pacific Grove Museum of Natural History No. 2348;
female. SR(a) 22-26 Jan. 1969; Pacific Grove (Baldridge and Chandik 1969,
Remsen field notes); found by A. Baldridge and also seen by L. C. Binford, T.
Chandik, D. DeSante, J. Greenberg, R. Greenberg, J. V. Remsen et al. P(a) 25
Jan.-22 Feb. 1969; Monterey harbor (Baldridge and Chandik 1969); found and
photographed by A. Baldridge and also seen by R. L. Branson, A. Craig, J. Craig,

D. DeSante, P. Devillers, G. McCaskie, W. Reese, J. V. Remsen, G. S. Suffel, V.
L. Yadon et al. SR(b) 25 Jan. 1969; Moss Landing (Baldridge and Chandik 1969);
seen by J. Greenberg and R. Greenberg. SR(a) 29 Dec. 1969; Point Joe (Baldridge
and Chandik 1970); seen by A. Baldridge, D. DeSante and R. LeValley from a
boat one-half mile offshore. MS(a) 23 Jan. -6 Mar. 1971; Moss Landing (DeSante
and Wang 1971); found by J. Greenberg and R. Greenberg and seen by many
until 6 Mar. when found dead by H. L. Jones; Museum of Vertebrate Zoology
No. 162350; female. SR(b) 26 Jan. 1971; Moss Landing (DeSante and Wang 1971);
seen by R. Stallcup and D. A. Gaines; a different individual from that on 23 Jan-
6 Mar. 1971, which was also seen on the same day by Stallcup and Gaines. SR(a)
21 Jan.-15 Mar. 1972; Pacific Grove (DeSanteand LeValley 1972); found by A.
Baldridge and R. Stallcup and also seen by S. F. Bailey, D. DeSante, G. S. Keith,
R. LeValley, J. V. Remsen, A. Small et al. SR(a) 26 Jan.-4 May 1972; Monterey
harbor area (DeSante and LeValley 1972a, 1972b; Suffel pers. comm.; McCaskie
pers. comm.); found by G. S. Suffel and also seen by A. Baldridge, G. McCaskie
and R. Stallcup; possibly more than one bird involved. SR(a) 10 Nov. 1973;
Monterey harbor (Remsen and Gaines 1974); seen by L. C. Binford, J. Greenberg,
P. Greenberg and W. McLeod. SR(a) 9-10 Jan. 1974; Monterey harbor (Stallcup

18

YELLOW-BILLED LOON

and Greenberg 1974, Suffel pers. comm.); found by A. Baldridge and also seen
by W. Anderson, H. L. Jones, P. Metropulos, G. S. Suffel, V. L. Yadon et al.;
this bird is considered to be a different individual from that on 10 Nov. 1973
because the harbor and surrounding area were searched many times without suc-
cess between the two sightings.

San Mateo Co. SR(a) 17-25 Jun. 1973. Princeton Harbor, Half Moon Bay
(Remsen and Gaines 1973); found by L. C. Binford and J. V. Remsen and also
seen by S. F. Bailey, B. G. Elliott, D. Roberson, S. Terrill et al.

Sonoma Co. P(b) 20 Oct. 1968; Bodega Bay (Chandik and Baldridge 1969);
photographed by W. Anderson. SR(a) 17 Jan. 1971 (not 18 Jan. as in DeSante
and Wang 1971); Bodega Bay; seen by B. Broadbooks (pers. comm.).

OREGON

Clatsop Co. SR(b) 8 Mar. 1969; Columbia River mouth (Crowell and Nehls
1969); seen by M. Konindyke and H. B. Nehls.

Coos Co. P(a) 15 Jul. 1972; Coos Bay (Crowell and Nehls 1972b; includes
photograph); found and photographed by P. A. Buckley.

Tillamook Co. SR(b) 15 Mar. 1969; Tillamook River mouth (Crowell and
Nehls 1969); seen by J. B. Crowell, Jr. and S. Janes.

NEVADA

Washoe Co. SR(a) 6 Jan. 1973; Incline Village, Lake Tahoe; seen by D. DeSante
and J. Farness (DeSante pers. comm.); previously unpublished; excellent substanti-
ating details are on file with us and the Regional Editors of American Birds (Mid-
dle Pacific Coast Region).

BAJA CALIFORNIA, MEXICO

MS(b) 24 Nov. 1968; Los Coronados Islands; San Diego Natural History Mu-
seum No. 36831; juvenal female (Jehl 1970). SR(a) 30 Jun. 1973; nine miles
south of San Felipe on the Gulf of California; seen by D. Simon and W. F. Simon
(Simon and Simon 1974).

APPENDIX B. Published records of the Yellow-billed Loon from the western
United States not considered acceptable at this time. We do not wish to contend
that all of these records were not of Yellow-billed Loons, but only that the sub-
stantiating details are either inadequate or not available. See Appendix A for ex-
planation of system employed.

CALIFORNIA

Humboldt Co. SR(a) 19-23 Mar. 1969; Big Lagoon (Yocum and Harris 1975);
insufficient details. SR(a) 30 Dec. 1973-1 Jan. 1974; Humboldt Bay (Stallcup
and Greenberg 1974, Yocum and Harris 1975); descriptions indicate Common
Loon.

19

YELLOW-BILLED LOON

Marin Co. SR(a) 28 Apr. 1965; Stinson Beach (see Chandik and Baldridge
1968); insufficient details. SR(a) 4 Mar. 1969; Limantour Estero, Point Reyes
National Seashore (Baldridge and Chandik 1969); insufficient details. SR(a) 1
Jan. 1973; Drake’s Bay, Point Reyes National Seashore (Homem 1973); insuffi-
cient details.

Sonoma Co. SR(a) 26 Dec. 1970; Bodega Bay (McLean 1971); insufficient
details. SR(b) 21 Jan. 1971; two birds; Bodega Bay (Homem 1971a); no details
available. SR(a) 25 Feb. 1971; Bodega Bay (Homem 1971b); insufficient details.
SR(b) 13 Feb. 1972; Bodega Bay (Homem 1972b); no details available. SR(a)
10 Dec. 1973; Bodega Bay (Stallcup and Greenberg 1974); insufficient details.

COLORADO

Adams Co. MS(a) 7 Nov. 1922; Brighton (Bailey and Lincoln 1954, A.O.U.
Check-list 1957, Bailey and Niedrach 1965); Denver Museum of Natural History
No. 7807, not 7808 as reported by Bailey and Niedrach (1965); we have examined
this specimen and found it to be a typical Cavia immer in all characters.

20

NOTES

BOREAL OWL SIGHTING IN
YELLOWSTONE NATIONAL PARK

CRAIG R. KUCHEL, 430 South Sixth East, Missoula, Montana 59801
ROBERT A. GARROTT, 1314 Harrison Street, Missoula, Montana 59801

On 3 February 1974 at 1400 we located a Boreal Owl (Aegolius funereus)
approximately 1 km northwest of Soda Butte in the Lamar Valley of northern
Yellowstone National Park, Wyoming (44° 50' N, 110”10'W). The sighting oc-
curred in a fairly open stand of Douglas-fir {Pseudotsuga menziesii) and Lodge-
pole Pine (Pinus contorta). When first sighted the owl was perched on a dead
limb 2 m above the ground, but later flew 10 m to a live Douglas-fir where it
perched 4 m above the ground. Seemingly undisturbed by our presence, the owl
allowed us to approach within 5 m to observe and photograph it for nearly an
hour (Figure 1).

The only previous record of the Boreal Owl in Yellowstone Park was a dead
bird found during the winter of 1951 (Arnold 1951). The one other Wyoming
record is a sight record for December 1927 (McCreary 1937).

Of six apparently reliable Montana records, four were between September and
February. Saunders (1921) reported a specimen taken in 1902 near Columbia
Falls although the specimen is not now known to exist. A fresh road kill was
discovered near Bozeman in September 1964. This specimen is presently in the
Montana State University collection (Skaar 1969). In November 1959 a Boreal
Owl was photographed repeatedly near Missoula (Hoffmann and Hand 1962). The
remaining Montana records are sight records, the most recent being of 3 depend-
ent young near the Canadian border in Glacier National Park in July 1973 (Rogers
1973).

Washington’s only undisputed record is a specimen collected near Pullman 10
January 1974 (Rogers 1974).

Idaho records reveal only two specimens, both collected in the extreme north-
ern portion of the state (Burleigh 1972).

Of five records which exist for Colorado, three are speeimens collected in Octo-
ber and November (Bailey and Niedrach 1967). The fourth is a specimen which
was found dead near Estes Park in April (Scott 1970). The fifth record, occurring
in August, included two juveniles, one of which was collected (Baldwin and Kop-
lin 1966).

The species’ winter range as described by the AOU Check-list includes northern
Montana and extends as far south as southern Idaho and Colorado. The breeding
range covers much of northwestern Canada and Alaska, but nowhere extends as
far south as the Rocky Mountain states (AOU 1957). However, Baldwin and
Koplin (1966) cite the 14 August 1963 observation of two juveniles (one collect-
ed) in north-central Colorado as evidence of isolated breeding units considerably
south of the species’ normal breeding range. Bent’s (1938) feeling that the species
is relatively nonmigratory tends to support this view. This hypothesis gains fur-
ther support from the findings of Voous (1960) that the Boreal Owl in Asia oc-
curs in small disjunct breeding units south of the normal breeding range.

In light of the strong possibility that small, isolated breeding units of the Bore-
al Owl may exist south of the contiguous breeding range, all observations in the
northern United States should be carefully documented.

Western Birds 6:21-23, 1975

21

22

Figure 1 Horeal Owl (Aegoluis f'mieveus) photographed 1 km northwest of Soda Hutte in the I.amar Valley of northern Yellow-
stone National Park, Wyoming on 3 February 1974 , „

Photo by Robnl A (,arrott

NOTES

LITERATURE CITED

American Ornithologists’ Union. 1957. Check-list of North American birds. Fifth
ed. Am. Ornithol. Union, Baltimore, Md.

Arnold, M. 1951. Arctic Owl. Yellowstone Nature Notes 25:23.

Bailey, A. M. and R. J. Niedrach. 1967. Pictorial check-list of Colorado birds.
Denver Museum of Natural History, Denver.

Baldwin, P. H. and J. R. Koplin. 1966. The Boreal Owl as a pleistocene relict
in Colorado. Condor 68:299-300.

Bent, A. C. 1938. Life history of North American birds of prey, part 2. U. S.
Natl. Mus. Bull. 170:220-228.

Burleigh, T. D. 1972. Birds of Idaho. Caxton Printers Ltd., Caldwell, Idaho.

Hoffmann, R. S. and R. L. Hand. 1962. Additional notes on Montana birds. Mur-
relet 43:29-35.

McCreary, O. 1937. Wyoming bird life. Burgess Publishing Co., Minneapolis.

Rogers, T. H. 1973. The nesting season. Northern Rocky Mountain-intermountain
region. Am. Birds 27:895.

Rogers, T. H. 1974. The winter season. Northern Rocky Mountain-intermountain
region. Am. Birds 28:666.

Saunders, A. A. 1921. A distributional list of the birds of Montana. Pac. Coast
Avif. No. 14.

Scott, O. K. 1970. The spring migration. Great Basin, central Rocky Mountain
region. Aud. Field Notes 24:628-630.

Skaar, P. D. 1969. Birds of the Bozeman latilong. P. D. Skaar, Bozeman, Montana.

Voous, K. H. 1960. Atlas of European birds. Nelson Publishing Co., New York.

23

NOTES

EFFECTIVENESS OF BROWN CREEPER’S
CONCEALMENT BEHAVIOR

B. RILEY McClelland, School of Forestry, University of Montana, Missoula,
Montana 59801

During a study of the relationships between forest snags and cavity-nestirjg
birds in the northern Rocky Mountains, I observed the effectiveness of the Brown
Creeper’s (Certbia familiaris) cryptic color pattern and behavioral response. The
combination made the bird nearly undetectable near its nest site on an Engelmann
Spruce (Picea engelmannii) snag. The nest tree was located on the Coram Experi-
mental Forest, Flathead National Forest, northwestern Montana, at an elevation
of 5350 feet.

The nest site was 27 feet above the ground in a totally dead snag 74 feet high
with a D.B.H. of 17 inches. The snag still retained most of its branches and bark.
On 18 June 1974 I had been observing adult creepers enter their nest, located in
a cavity between the trunk of the tree and a section of partially detached bark.
The birds were carrying food and apparently feeding young, though the latter
were not seen or heard.

As I watched, an adult flew to the tree, landed several feet below the nest, and
“hitched” toward the entrance. When suddenly startled by a slight movement
of my leg, the bird immediately “froze” in a position in which its body and out-
stretched wings were pressed tightly against the tree. Its mottled color pattern
blended perfectly with the scaly bark of the spruce. I took my eyes off the bird
to ascertain how difficult it would have been to locate had I not been following
its movement before it “froze”. Several minutes were required to relocate the
bird even though I was only 25 feet from the tree, was using 7x binoculars and
knew the bird’s relative position on the tree. The creeper remained in this station-
ary, perfectly camouflaged position for another five minutes, after which it con-
tinued on to its nest.

This observation appears to be an exception to Bent’s (U.S. Natl. Mus. Bull.
195, 1948) view that the creeper does not seem to look upon man as a danger.
This behavior pattern may be common during the nestling period. However, the
creepers at another nest discovered in a Douglas-fir {Pseudotsuga menziesii) during
the 1974 study never assumed the above-described position in response to my
presence. This pair also appeared to be feeding young.

Brown Creeper nests are not easily located, because of their location (between
bark and main stem) and the adult’s behavior and cryptic color pattern. Bent
(ibid.) describes the difficulty in locating creepers because of their inconspicuous
color. One instance is cited wherein creepers rested in the shadows of limbs, thus
adding to their concealment. He also cites an account by William Brewster de-
scribing the escape of a Brown Creeper that was being pursued by a shrike. The
creeper flattened itself against the bark of a tree and avoided detection. Bradford
Torrey, also cited by Bent (ibid.: 67) describes a similar defensive response of a
creeper to the scream of a hawk. When the hawk screamed overhead, the creeper
“flattened himself against the trunk spreading his wings to their very utmost and
ducking his head,” making him nearly impossible to detect.

I thank Drs. Phillip Wright and Sidney Frissell, University of Montana, Curtis
Halvorson, U.S. Fish and Wildlife Service, and Dr. Laurence Binford, California
Academy of Sciences, for reviewing this note. The study is sponsored jointly_^by
the School of Forestry— University of Montana, U.S. Forest Service, Montapa
Cooperative Wildlife Unit and the U.S. Fish and Wildlife Service.

24

Western Birds 6:24, 1975

NOTES

THE STATUS OF THE GRAY FLYCATCHER
IN WASHINGTON STATE

NORMAN LAVERS, 873 Samish Island Road, Bow, Washington 98232

Larrison (1970) reported seeing on 31 May 1970 a bird with the field marks
and song of the Gray Flycatcher (Empidonax wrightii) in a stand of Yellow Pines
{Pinus ponderosa) in Wenas Park, 17 km north northwest of Naches, Yakima
County, Washington. This undocumented sight record was the first report of the
species in the state. On 13 June 1972 Terence R. Wahl closely observed a bird
with the field marks of the Gray Flycatcher in the Columbia National Wildlife
Refuge, near Othello, Adams County, in willows (Salix) surrounded by sagebrush
(Artemisia) (Rogers 1972, T. R. Wahl pers. comm.). Between 26-30 May 1972
Yaich and Larrison (1973) observed and photographed a Gray Flycatcher at Wenas
Park in a nest “some 6 feet from the ground at the base of one of the lowermost
branches of a small pine tree.’’ The nest contained two eggs. In a note appended
to this report, Larrison described finding two more nests and an additional 10
Gray Flycatchers within 6 km of Wenas Park, 23-28 May 1973. These birds were
mainly in Yellow Pine groves, though one nest was in willows. Larrison concluded
“The species is apparently becoming established in at least this part of the yellow
pine belt of the eastern Cascades in Washington.’’

The discovery Cheryl Lavers and I subsequently made of a small population
of Gray Flycatchers with well grown fledglings in Klickitat County, near the
southern border of the state, confirms successful nesting in Washington. More
importantly, it begins to outline the distribution of the species in the state and
suggests its point of origin from Oregon. Our observations are reported here in
detail.

On 27 June 1973 near the Klickitat Wildlife Recreation Area headquarters
midway on the Goldendale to Glenwood road, Klickitat County, our attention
was caught by some strikingly pale pearl gray Empidonax flycatchers. An adult
bird was feeding two well grown fledglings. The birds were in plain sight and very
tame, completely ignoring us while we observed them through 7x35 binoculars
from distances of 8 to 13 m. Lighting conditions were ideal. Here is our de-
scription, discussed and written up on the spot after 15 or 20 minutes of close
study: Head and back, very pale, bright, pearl gray, with no admixture of olive
or brown; tail, brownish; underparts white, or perhaps grayish around the breast,
with no trace of yellowish; eyering and wingbars well marked and prominent;
lower mandible prominently bright orangey flesh color (two or three times we
saw black at the tip of the lower mandible, but could not be certain if this was
mandible color, or merely an insect carried at the tip of the bill). We both had
the impression that these were quite large Empidonax. Behavior: these birds and
others we observed were foraging and singing from ground level to about 4 m up
in the lower branches of trees. Unlike many Empidonaces, they showed a clear
preference for remaining out in the bright sun. If one landed in a shady place,
it immediately shifted its position as much as 0.5 m to get back into the sun.
When they flipped their tails, unfailingly they first lowered, then raised the tail,
a trait of the Gray Flycatcher, the opposite of other Empidonaces (Phillips et al.
1964). Voice: at the time the non-singing parent bird was feeding the young,
three or more flycatchers were singing in the immediate vicinity. I observed one
of these from a distance of 8 to 10 m. In plumage it was identical to the first
birds observed. It sang constantly, singing one complete song about every five
seconds. The song was regular and invariable, with two parts, the second part
higher than the first. To me it sounded like choop cheep. To Cheryl’s more

Western Birds 6:25-27, 1975

25

NOTES

discriminating ear, it sounded like ss-pit ss-peet. I listened to the song 40 or more
times and the only variation was once when it went choop cheep pit. The range
and quality of the voice was somewhat similar to that of a Dusky Flycatcher (£.
oberholseri) but differed in being divided into discrete, regular two-note units,
whereas the Dusky’s song (one or two were singing nearby) was more or less
continuous, its three or four elements repeated in random sequence. Two or
three other birds singing right near the one I was observing were singing an identi-
cal song, equally regular and unvaried. The habitat was open Yellow Pine-Garry
Oak (Quercus garryflwa)— Douglas-fir (Pseudotsuga taxifolia) association, with a
bare understory. There was no sagebrush anywhere in this area of open wood-
land and oak savannah.

In the experience of Harry B. Nehls (pers. comm.), who has studied the species
extensively in Oregon, and in most published accounts of the species (e.g. Hoff-
mann 1927), the presence of some sagebrush is considered an essential ingredient
for breeding habitat. However, the two fledglings we watched being fed in Klicki-
tat County indicate nesting occurred close to where we saw them, in an area with
no sagebrush. Wenas Park, where Yaich and Larrison made the majority of their
sightings, is in a rather similar area of open woodland in which sagebrush is not
prominent, though large tracts of sagebrush begin 2-3 km to the east.

In the summer of 1974, alerted birders began searching for the species in
Yellow Pine woodland. Wahl (pers. comm.) investigated the Klickitat County
area where I had discovered the birds the previous summer and found it “swarm-
ing” with Gray Flycatchers, Eugene Hunn (pers. comm.) checked the Wenas
Park area and found it similarly “swarming”. Bill Tweit (pers. comm.) found
several in a stand of yellow pines about 13 km northeast of Wenas Park. Wahl
recorded their song in both Klickitat County and Wenas Park.

On 29 June 1974 a male Gray Flycatcher was collected at Wenas Park (speci-
men to Burke Museum, University of Washington). In-hand characters of this
specimen, compared with typical Dusky and Hammond’s (£. bammondii) Fly-
catchers (after the key in Phillips and Lanyon 1970), are the following: lower
mandible bi-colored, pale yellow basally, dusky tip (nearly always uniformly col-
ored in the Dusky Flycatcher); primary coverts with edges conspicuously paler
than their centers (inconspicuous in Dusky); outer web of outer retrix, as seen
from above, definitely whitish (unlike Hammond’s); bill, measured from anterior
edge of nostril, 9.5 mm (over 8.0 mm in the Gray, almost always 7.5 mm or less
in Hammond’s); tail 59 mm (56.6 mm or more in Gray, 55.0 or less in Ham-
mond’s); wing chord 70 mm, for a wing minus tail difference of 1 1.0 mm (usually
more than 7.0 mm in Gray, less than 8.0 mm in Dusky); 10th primary longer than
4th (almost always the reverse in Dusky); 9th primary longer than 6th (about equal
in male Dusky).

DISTRIBUTION IN THE STATE

Nehls (pers. comm.) gives the following as the northern limits of the Gray Fly-
catcher’s range in Oregon: “North to the southern base of the Ochoco Mountains
in the area about Post and Paulina, skirting the base of the Blue Mountains and
east to perhaps Huntington. The western limits are found at the base of the Cas-
cade Range. A finger of the population runs north along the west side of the
Deschutes River into the Warm Springs Indian Reservation, but not beyond. On
the east side of the river to Madras.”

The small population we located in Klickitat County is in a line about 128
km directly north of this northerly extending “finger.” This suggests that this
is the area where the species funnels into Washington from Oregon, following up
the Deschutes River to where it empties into the Columbia River, and from there

26

NOTES

proceeding north in Klickitat County to where we found them. This same line
continued north another 110 km reaches the Wenas Creek area of Yaich and Lar-
rison’s sightings. The eastern slopes of the Cascades would inhibit extension very
far west of this line. Mountainous country above Wenas Creek might impede ex-
tension north. But Wahl’s 1972 sighting suggests the species might conceivably
extend east as far as Othello, Adams County, Washington.

The south central Washington locations where the various sightings of Gray
Flycatchers have been made are only a small fraction of an extensive area little
explored by birders. Further it is an area in which several species of Empidonax
abound. Empidonax flycatchers are diffieult, and in particular many Washington
birders are unfamiliar with Gray Flycatchers. Furthermore, some of these birds
are evidently nesting outside their expected habitat. Nehls (pers. comm.) speaks
of this species occurring in Oregon in dense but often widely separated “colonies.”
There may be a number of these small “colonies” undetected in Washington.
Within the area of Klickitat, Yakima, southern Grant, and southwestern Adams
counties, careful search of open pine woodland and of pine groves or willow
clumps bordering sagebrush from late May into July will probably show the spe-
cies to be well established in the state, though occurring in widely separated
“colonies.”

ACKNOWLEDGMENTS

I would like to thank Terence R. Wahl for help and encouragement in writing
this paper, Harry B. Nehls for notes on the Gray Flycatcher in Oregon, and Lynn
Paulson for preparing the specimen and making the critical measurements.

LITERATURE CITED

Hoffman, R. 1927. Birds of the Pacific states. Houghton Mifflin Co., Boston.
Larrison, E. J. 1970. Sight record of the Gray Flycatcher in Washington. Murre-
let 52;40.

Phillips, A. R. and W. E. Lanyon. 1970. Additional notes on the flycatchers of
eastern North America. Bird-Banding 41 : 190-97.

Phillips, A., J. Marshall and G. Monson. 1964. The birds of Arizona. Univ. of
Arizona Press, Tucson.

Rogers, T. H. 1972. The nesting season. Northern Rocky Mountain-Intermountain
region. Am. Birds 26:881.

Yaich, J. A. and E. J. Larrison. 1973. Nesting record and behavioral observations
on the Gray Flycatcher in Washington. Murrelet 54: 14-16.

27

NOTES

SECOND RECORD FOR THE
PHAINOPEPLA IN COLORADO

JOEL D. HUBBARD, ALLEN B. CROCKETT, and PAULA L. HANSLEY, De-
partment of Environmental, Population, and Organismic Biology, University of
Colorado, Boulder, Colorado 80302

Prior to 1973, the Phainopepla (Phainopepla nitens) had been reported in
Colorado only once (Bailey and Niedrach, Birds of Colorado, Denver Museum of
Natural History, 1965:846). However, on 15 December 1973 we discovered a
Phainopepla while participating in the annual Christmas Bird Count in Boulder,
Boulder County, Colorado. The bird was observed at length and photographed
by us for three days, during which time it was seen by approximately 25 others.

The first sighting of this species in Colorado occurred on 29-30 August 1965
at Platteville in Weld County, approximately 44 km northeast of Boulder. That
individual was an immature male and was already showing some glossy black
feathers mixed in with its overall gray color. The bird we saw was gray with no
traces of black, suggesting that it was a female. The bird was observed at close
range and in excellent light, and all of the distinctive field marks— long crest,
reddish-brown eye, white wing patch, and faint double wing bar— were clearly
visible. The soft, low whistle of the species was heard frequently and further
corroborated the identification. The most convincing of several 35 mm transpar-
encies obtained is on deposit with the Official Records Committee of the Colorado
Field Ornithologists.

During its stay, the Phainopepla was consistently associated with riparian habi-
tat along Boulder Creek, immediately east (downstream) of the mouth of Boulder
Canyon. The area, a city park west of downtown Boulder, lies at an elevation of
1810 m. The habitat of the park, like much of that along Boulder Creek, is a
mixture of deciduous trees and dense deciduous brush; the brush was especially
favored by the Phainopepla.

The Phainopepla spent much of its time sunning, preening, and foraging in the
leaf litter or feeding among the shrubs on wild grapes {Vitis riparia) which had
not yet dropped from vines. Flying insects were occasionally active above the
stream, as they often are in this area on warm days during a mild autumn, and
some bouts of flycatching by the Phainopepla were observed. This individual
was frequently seen in the company of a Townsend’s Solitaire {Myadestes town-
sendi). Often the solitaire would appear first, utter a few call notes in the distance,
then arrive at streamside and give its typical warbling song. Shortly thereafter,
the Phainopepla would appear and begin foraging near the solitaire; both birds oc-
casionally flew to the water’s edge to drink. The reason for this association is specu-
lative at best; perhaps their somewhat similar appearance prompted the fraterni-
zation, or the Phainopepla may have been attracted by the solitaire’s whistled
call notes. On a few occasions, the two seemed to exchange calls. Coincidentally,
recent biochemical evidence presented by Sibley (Auk 90:394-410, 1973) suggests
a much closer relationship between the Phainopepla and the solitaire than had
previously been supposed.

The typical range of this rather sedentary species brings it no closer to north-
central Colorado than southern Utah (AOU Check-list 1957). If the Phainopepla
occurs more frequently in Colorado, it is probably in the southwestern part of
the state, closer to the edge of its range and in more familiar habitat. However,
that area is sparsely populated, and a rare straggler could easily be overlooked.

28

Western Birds 6:28, 1975

NOTES

THE SPRAGUE’S PIPIT REACHES CALIFORNIA

GUY McCASKIE, San Diego Natural History Museum, P. O. Box 1390, San Diego,
California 92112

On 19 October 1974 a party of us flushed a Sprague’s Pipit (Anthus spragueii)
from a cutover alfalfa field in the Tijuana River Valley just south of Imperial
Beach, San Diego County, California. Additional searching of this field on the
19th revealed at least three Sprague’s Pipits, and continued checking of the area
during the next two weeks indicated one or two individuals were present through
27 October. On 24 October I collected an adult female weighing 20.3 g from the
field, and it is now No. 38980 in the San Diego Natural History Museum.

Other birds present in the alfalfa field were some 250 Water Pipits (A. spino-
letta), up to six Red-throated Pipits (A. cervinus), about 50 Savannah Sparrows
(Passerculus sandwichensis), at least one Vesper Sparrow (Pooecetes gramineus)
and a half dozen Chestnut-collared Longspurs (Calcarius omatus). The Water and
Red-throated pipits remained as a flock in areas where the alfalfa was shortest, but
the Sprague’s Pipits usually remained apart and alone in areas of taller plants.
A Sprague’s Pipit occasionally moved into the vicinity of the large flock of pipits,
but even then did not truly associate with them, acting more as an individual
apart from the flock.

The Sprague’s Pipits differed slightly in behavior from the other pipits, tend-
ing to run rather than fly when approached by an observer. In addition the
Sprague’s Pipits were not seen to bob their tails as did both the Water and Red-
throated pipits. In appearance the Sprague’s Pipit more closely resembled the
Red-throated than the Water Pipit, however, spragueii lacked the bold supercil-
iary and heavy breast streakings of cervinus, and had a scaly look to the upper-
parts instead of the conspicuous streaking of the Red-throated Pipit.

The Sprague’s Pipit nests in the prairies of the northern Great Plains, and
winters primarily from Texas south to Veracruz in eastern Mexico. It is scarce
along the eastern side of the Rocky Mountains, being considered an uncommon
straggler to eastern Colorado by Bailey and Niedrach (1965), and reported from
only three localities in extreme eastern New Mexico by Hubbard (1970).

West of the Rocky Mountains, Behle and Perry (1975) consider the Sprague’s
Pipit a rare winter visitant and transient in Utah, based on several sight records for
the Salt Lake City and Cedar City areas; Phillips et al. (1964) treat it as rare in
Arizona, on the basis of seven records; and Phillips and Amadon (1952) dis-
covered at least four individuals near Sasabe In extreme northern Sonora, Mexico,
between 19 and 22 October 1948. Two of the Arizona records are from the ex-
treme western part of the state, with one near Topock on the Colorado River
(27 September 1949) and the other on the Tule Desert west of the Sierra Pinta
Mountains in extreme southern Yuma County (30 December 1958).

The Sprague’s Pipit has been included among the species listed on two Christ-
mas Bird Counts taken in California: the San Bernardino count of 30 December
1962 (Audubon Pdeld Notes 17:284, 1973) and the Orange County (central and
coastal) count of 29 December 1968 (AFN 23:417^18, 1969). Christmas Bird
Counts, however, contain numerous errors as the results of misidentifications by
participants, and poor screening by count compilers. Since no details accompany
the reports they are best disregarded. A Sprague’s Pipit reported at Lava Beds
National Monument in northeastern California on 30 April 1952 (AFN 6:261,
1952) was not even treated as rare, and cannot be considered a valid record.
A pipit, believed to be a Sprague’s, at Goleta, Santa Barbara County, on 8 Oct-
ober 1964 (AFN 19:80, 1965) was clearly not a Water Pipit, but the description
of the bird does not rule out the possibility of a Red-throated Pipit which now

Western Birds 6:29-30, 1975

29

NOTES

appears more likely. The birds at Imperial Beach in 1974 must therefore be
considered the only valid record to date for California.

Considering the bird’s normal range, and its continued occurrence in Arizona
(see Am. Birds 28:87-90, 1974 and personal observation of ca. 10 at the mouth of
Gardner Canyon in Pima County 5 February 1972), we can expect additional
Sprague’s Pipits to appear in California. However, observers must treat all records
with caution, for Red-throated Pipits do occur somewhat regularly, and the
Pechora Pipit {A. gustavi) is a potential straggler to the state.

LITERATURE CITED

Bailey, A. M, and R, J. Niedrach. 1965. Birds of Colorado, vol. II. Denver Mus.
Nat. Hist., Denver.

Behle, W. H. and M. L. Perry. 1975. Utah birds: Check-list, seasonal and ecol-
ogical occurrence charts, and guides to bird finding. Utah Mus. Nat. Hist.,
Salt Lake City.

Hubbard, J. P. 1970. Check-list of the birds of New Mexico. New Mexico Orni-
thol. Soc. Publ. no. 3:1-103.

Phillips, A. and D. Amadon. 1952. Some birds of northwestern Sonora, Mexico.
Condor 54:163-168.

Phillips, A., J. Marshall and G. Monson. 1964. The birds of Arizona. Univ. Ari-
zona Press, Tucson.

30

NOTES

BLACK-THROATED BLUE WARBLER IN UTAH

RICHARD D. PORTER, U.S. Fish and Wildlife Service, Intermountain Forest and
Range Experiment Station, 735 North, 500 East, Provo, Utah 84601

LARRY C. PRITCHETT, Utah State University Range Technician, Ecology Cen-
ter, Logan, Utah 84322

On 27 September 1974 we collected a male Black-throated Blue Warbler (Den-
droica caerulescens) in immature plumage at the headquarters of the Desert Exper-
imental Range (1,601 m elev.) in Millard Co., Utah, 75.6 km west of Milford. The
specimen (No. 5 369, Brigham Young Univ. Life Science Museum, Provo, Utah)
weighed 10 g. It was assigned to the race caerulescens by Mrs. Roxie C. Laybourne
of the National Fish and Wildlife Laboratory, U.S. National Museum. All but
the frontal portions of the bird’s skull were 2-layered and pneumatosized. The
warbler, in company with Yellow-rumped (Audubon’s) Warblers (Dendroica coro-
nata), was in a planted windbreak of Juniper, Russian Olive, Honey Locust, Black
Locust, and Siberian Elm adjacent to the buildings and near a small permanent
source of water.

This apparently is the first specimen of this warbler collected from the state of
Utah, although several sight records have been reported. Charles Lockerbie and
Guy Emerson noted the species at Salt Lake City, Salt Lake Co., on 24 October
1953 (Scott, Audubon Field Notes 8:33, 1954), William H. Behle recorded one in
South Willow Canyon, Stansbury Mountains, Tooele Co., Utah, on 16 October
1955 and three were seen in 1963 near Cedar City, Iron Co., by Stewart Murie on
20 May, 19 August and 10 September (Behle and Perry, Utah birds: Check-list,
seasonal and ecological occurrence charts and guides to bird finding. Utah Mus.
Nat. Hist,, Univ. Utah, 1975). This species, along with other species of eastern
warblers, seemingly has been observed in the western United States more frequent-
ly in recent years than formerly; this has been attributed to more observers in the
field now than previously (Austin, Condor 73:455, 1971). The several Utah re-
cords probably are a part of this phenomenon.

Western Birds 6:31, 1975

31

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