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A new species of sage-grouse (phasianidae: Centrocercus) from southwestern colorado

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The Gunnison Sage-Grouse (Centrocercus minimus) is described as a new species from southwestern Colorado and contrasted with the Sage-Grouse (Centrocercus urophasianus) from northern Colorado and western North America. Gunnison Sage-Grouse differ from all other described sage-grouse (C. u. urophasianus, C. u. phaios) in morphological measurements, plumage, courtship display, and genetics. The species currently is limited to 8 isolated populations in southwestem Colorado and adjacent San Juan County, Utah. Total estimated spring breeding population is fewer than 5000 individuals with the largest population < Basin (Gunnison and Saguache counties), Colorado.
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445
Wilson Bull., 112(4), 2000, pp. 445–453
A NEW SPECIES OF SAGE-GROUSE
(PHASIANIDAE: CENTROCERCUS) FROM
SOUTHWESTERN COLORADO
JESSICA R. YOUNG,
1,7
CLAIT E. BRAUN,
2,6
SARA J. OYLER-M
C
CANCE,
3,4
JERRY W. HUPP,
5
AND TOM W. QUINN
4
ABSTRACT.—The Gunnison Sage-Grouse (Centrocercus minimus) is described as a new species from south-
western Colorado and contrasted with the Sage-Grouse (Centrocercus urophasianus) from northern Colorado
and western North America. Gunnison Sage-Grouse differ from all other described sage-grouse (C. u. urophas-
ianus, C. u. phaios) in morphological measurements, plumage, courtship display, and genetics. The species
currently is limited to 8 isolated populations in southwestern Colorado and adjacent San Juan County, Utah.
Total estimated spring breeding population is fewer than 5000 individuals with the largest population (
,
3000)
in the Gunnison Basin (Gunnison and Saguache counties), Colorado. Received 3 February 2000, accepted 29
June 2000.
FRONTISPIECE. Male Gunnison Sage-Grouse displaying, Gunnison Basin, Colorado. Original artworkpaint-
ed from life by Don Radovich.
Sage-Grouse (Centrocercus urophasianus;
Phasianidae; Tetraoninae) occur only in North
America, and historically occupied suitable
shrub-steppe habitats from eastern California,
Oregon, Washington, and southeastern British
Columbia east into western North Dakota,
South Dakota, northwestern Nebraska, south-
western Kansas, and adjacent Oklahoma (Al-
drich and Duvall 1955, Aldrich 1963, Johns-
gard 1973). The former distribution included
portions of 16 states and 3 Canadian provinc-
es. These grouse have been extirpated from 5
states (Arizona, Kansas, Nebraska, New Mex-
ico, Oklahoma) and 1 province (British Co-
lumbia; Braun 1998).
Two races of sage-grouse have been de-
1
Dept. of Natural and Environmental Sciences,
Western State College of Colorado, Gunnison, CO
81231.
2
Colorado Division of Wildlife, 317 West Prospect
Rd., Fort Collins, CO 80526.
3
U.S. Geological Survey, Midcontinent Ecological
Sciences Center, 4512 McMurray Ave., Fort Collins,
CO 80525.
4
Dept. of Biological Sciences, Univ. of Denver,
Denver, CO 80208.
5
Alaska Biological Science Center, U.S. Geological
Survey, 1011 East Tudor Rd., Anchorage, AK 99503.
6
Present address: GROUSE INC., 5572 North Ven-
tana Vista Rd., Tucson, AZ 85750.
7
Corresponding author; E-mail: jyoung@western.
edu
scribed previously. Centrocercus urophasi-
anus phaios is restricted to the area immedi-
ately east of the Cascade Mountains in
Oregon, north into Washington and south into
extreme northeastern California (Aldrich
1946). Centrocercus urophasianus urophasi-
anus was reported to occur throughout the re-
mainder of the range (Aldrich and Duvall
1955, American Ornithologists’ Union 1957,
Aldrich 1963).
Management activities by the Colorado Di-
vision of Wildlife to increase the knowledge
about sage-grouse within the state resulted in
systematic collection of wings from hunter
harvest throughout the state starting in the
mid-1970s. In 1977, wings from birds in the
Gunnison Basin (Gunnison and Saguache
counties) were noted to be smaller (based on
measurements of primaries 10, 9, and 1) than
wings obtained elsewhere in the state. Sub-
sequent studies of grouse in the Gunnison Ba-
sin in the mid-1980s (Hupp 1987) and early
1990s (Young 1994) revealed significant dif-
ferences in morphometrics (Hupp and Braun
1991), breeding behavior, and plumage
(Young et al. 1994) compared to other popu-
lations of sage-grouse. Recent studies of the
mitochondrial and nuclear allele frequencies
of sage-grouse in Colorado have revealed ad-
ditional significant differences (Kahn et al.
1999, Oyler-McCance et al. 1999).
446
THE WILSON BULLETIN
Vol. 112, No. 4, December 2000
Based on published and unpublished infor-
mation on morphometrics, plumage appear-
ance, behavior, and genetics, we propose that
the sage-grouse first described from the Gun-
nison Basin, Colorado by Braun and Young
(1995), be recognized as a new taxon. It ful-
fills the criteria for species distinction by sev-
eral common species concepts including the
biological species concept, the recognition
concept, and the evolutionary species concept.
Further, we propose that all other sage-grouse
continue to be named with the English name
Sage-Grouse. Our recommendation is not in
agreement with the AOU Checklist Commit-
tee (2000), which recommends all other sage-
grouse be named Greater Sage-Grouse. Inter-
nationally, nationally, and regionally the com-
mon name for the latter species for the past 5
years has been Northern Sage Grouse based
on the relative locality from which it was first
described. Following this point in the manu-
script, the common name Sage-Grouse is used
to refer to the species which has been previ-
ously described in the scientific literature and
in professional abstracts as Northern Sage-
Grouse or Sage Grouse.
GUNNISON SAGE-GROUSE,
CENTROCERCUS MINIMUS
NEW SPECIES
Holotype.—Denver Museum of Natural
History (DMNH) 40722, adult (2
1
years of
age) male obtained by C.E.B. and J.R.Y. on
10 May 1993 approximately 23 km southeast
of Gunnison, Gunnison County, Colorado.
This locality is in the South Parlin area on
public land administered by the Bureau of
Land Management (BLM). This bird was pre-
pared as a flat skin with skeleton. DMNH
40723 was collected on the same date and at
the same location, also an adult male prepared
as a flat skin with skeleton.
Diagnosis.—A dark brown sage-grouse
with black underparts and prominent black,
long, thin, specialized, ornamental contour
feathers arising from the dorsal base and sides
of the neck on males (lost after breeding with
few apparent until molting in mid- to late No-
vember), coarsely barred brown, long tail
feathers with prominent white to yellow-white
bars, brown rounded wings, and feathered
gray-brown tarsi. Rounded air sacs (cervical
apteria) greenish-yellow within a white upper
breast, with scale-like feathers on males prom-
inent in spring. Females smaller than males,
similar in general plumage appearance but
without specialized ornamental contour feath-
ers arising from the dorsal base of the neck
and without the prominent white upper breast
and discernible air sacs of males. Tail length
shorter than males but with same coarsely
barred brown with prominent white to yellow-
white bars. Both sexes smaller in mass and
feather lengths than adult/yearling C. uro-
phasianus with no overlap. Strut rates are
slower and audible sounds differ markedly
from C. urophasianus during breeding dis-
plays.
Distribution.—Gunnison Sage-Grouse cur-
rently exist in 6, possibly 7, counties in south-
western Colorado (Braun 1995, Commons
1997) and 1 county in southeastern Utah (Bar-
ber 1991). The known historic distribution
(Fig. 1) of this species in Colorado was in
sagebrush (Artemisia spp.) communities be-
low 3000 m south of the Eagle and Colorado
rivers from near Leadville (Lake County)
south, and in sagebrush dominated shrub-
steppe habitat into the San Luis Valley to the
boundary with New Mexico and west to the
Utah state line. It was known to occur in
Grand and San Juan counties, Utah, south and
east of the Colorado River. The distribution of
the species was discontinuous within this area
(Rogers 1964, Braun 1995) separated by river
valleys and high forested mountains.
We hypothesize that sage-grouse formerly
native to New Mexico (Bailey 1928, Merrill
1967, Hubbard 1970) belong to this species.
This would exclude those trapped in Wyo-
ming and released at a number of locations to
supplement sage-grouse populations histori-
cally present in the northern areas of the state
(Merrill 1967). We found no museum speci-
mens from New Mexico (J. P. Hubbard, pers.
comm.), Arizona (Phillips et al. 1983), Kansas
(Goss 1883, Cable et al.1996), or Oklahoma
(Nice and Nice 1924, Sutton 1967) to test the
general hypothesis that sage-grouse in all of
these locations were Gunnison Sage-Grouse.
The areas in northern New Mexico and ex-
treme northeastern Arizona once had sage-
brush habitats that were mostly contiguous
with areas in Colorado and Utah presently oc-
cupied by Gunnison Sage-Grouse. The iden-
tity of the sage-grouse known to have oc-
447
Young et al.
NEW SPECIES OF SAGE GROUSE
FIG. 1. Current and historic distribution of Gunnison Sage-Grouse in Colorado and Utah.
TABLE 1. Live body mass (g) of Gunnison Sage-Grouse and Sage-Grouse from Colorado during the breed-
ing season.
Adult males Yearling males Adult females Yearling females
Gunnison
Mean (Sample size)
Standard error
Range
2141 (89)
12.6
1727–2435
1911 (21)
32.7
1622–2176
1204 (18)
16.3
1072–1327
1131 (20)
19.4
990–1335
Jackson County
a
Mean (Sample size)
Standard error
Range
3190 (465)
8.5
None given
2809 (445)
9.7 1745 (221)
10.2 1551 (186)
9.0
a
Data from Beck and Braun (1978).
curred in extreme southwestern Kansas and
adjacent northwestern Oklahoma is unknown
but we postulate that they too were Gunnison
Sage-Grouse because of their proximity to the
current range of the species.
MORPHOMETRICS
Body mass.—Mean live body mass of Gun-
nison Sage-Grouse captured during the breed-
ing season (late March–late May) was 27–
33% less than mean live body mass reported
by Beck and Braun (1978) for Sage-Grouse in
northern Colorado (Jackson County) during
April–May (Table 1). Live body mass of
Sage-Grouse in Jackson County, Colorado
was similar to that reported for Sage-Grouse
(including C. u. urophasianus and C. u.
phaios) throughout the rest of its range (Beck
and Braun 1978). Differences in body mass
between large and small bodied sage-grouse
were greatest for males (32–33%, ca 1000 g)
and slightly smaller for females (27–30%,
400–500 g; Table 1).
Length of primaries.—Fully replaced pri-
mary feathers 10, 9, and 1 were measured in
place by inserting a flexible ruler between pri-
maries 10 and 9, 9 and 8, and 2 and 1 and
recording the length from the feather insertion
to the tip of the primary. Wings were available
from sage-grouse harvested by hunters during
September hunting seasons in the Gunnison
Basin and in Jackson County, Colorado. Mean
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THE WILSON BULLETIN
Vol. 112, No. 4, December 2000
TABLE 2. Length (mm) of primary flight feathers (P10, P9, and P1) of Gunnison Sage-Grouse and Sage-
Grouse in Colorado in September.
Adult males
P10 P9 P1
Adult females
P10 P9 P1
Gunnison
Mean (Sample size)
Standard error
Range
166 (79)
0.43
158–179
216 (74)
0.55
203–226
151 (78)
0.30
144–159
139 (120)
0.54
128–155
182 (131)
0.32
169–196
130 (128)
0.32
120–138
Jackson County
Mean (Sample size)
Standard error
Range
179 (65)
0.59
167–190
230 (54)
0.79
214–240
167 (67)
0.51
151–176
147 (100)
0.39
139–157
193 (100)
0.54
179–210
141 (100)
0.45
130–151
TABLE 3. Mean beak measures (mm) of museum
a
specimens from Gunnison Sage-Grouse and Sage-
Grouse in Colorado. Sample size in parentheses.
Adult male
Gunnison Northern
Colorado
Adult female
Gunnison Northern
Colorado
Culmen
Nostril to tip
Width
31.7 (3)
14.3 (3)
16.0 (3)
39.1 (4)
16.6 (4)
21.7 (4)
28.0 (4)
12.9 (4)
13.8 (4)
30.6 (9)
14.5 (9)
17.1 (9)
a
Sample sizes of museum specimens of adult Sage-Grouse from Colorado
are small.
lengths of primaries were 8–16 mm shorter for
Gunnison Sage-Grouse when compared to
large bodied birds (Table 2). Differences were
greater for males (6–11%) than females (5–
8%). Primary lengths of Sage-Grouse in Jack-
son County, Colorado are similar to those of
Sage-Grouse in California, Nevada, Oregon
(including C. u. urophasianus and C. u.
phaios), Utah, and Wyoming (C. E. Braun,
unpubl. data).
Beak size.—Although sample sizes from all
known museum specimens are small, three
standard measures indicate that adult Gunni-
son Sage-Grouse from southwestern Colorado
have shorter and narrower beaks than Sage-
Grouse from northern Colorado (Table 3).
Hupp and Braun (1991) found similar differ-
ences in a larger sample of culmen lengths
between Gunnison Sage-Grouse and Sage-
Grouse in Jackson County.
Tail length.—Length of tail feathers of
males [x¯
5
347
6
0.5 (SE), n
5
36] is longer
in Gunnison Sage-Grouse than in other Sage-
Grouse (generally
,
315 mm), although this
character is easily altered by wear. Both sexes
of Gunnison Sage-Grouse have clearly defined
white or cream bars (width
5
5–7 mm) on the
rectrices, unlike the indistinct barring on the
tail feathers of other Sage-Grouse (Fig. 2).
Thus, the elaborate neck feathers of males and
the uniquely barred rectrices are the best field
identification characters for the Gunnison
Sage-Grouse.
PLUMAGE
Outside the breeding season, sage-grouse
throughout western North America are similar
in appearance. Overall coloration varies from
gray-brown to darker brown within a popu-
lation and changes seasonally because of
feather fading resulting from exposure to the
environment and molt replacement of body
feathers (C. E. Braun, pers. obs.). Sage-grouse
in southwestern Colorado and southeast Utah
differ from all other studied populations in
length and thickness of modified feathers on
the dorsal surface of the back and sides of the
neck of males during the breeding season
(Fig. 3). The elaborate long, thin black spe-
cialized ornamental contour body feathers that
arise from the dorsal base of the neck of Gun-
nison Sage-Grouse adult males (range 120–
173 mm, x¯
5
146
6
0.2, n
5
38) and 3–6
mm wide give an appearance of a black
‘‘ponytail’’ when displayed. In contrast, Sage-
Grouse have shorter and thinner (generally
,
115 mm long and 1 mm wide) dorsal neck
feathers.
BEHAVIOR
Gunnison Sage-Grouse are similar to Sage-
Grouse in that they have a lek mating system.
Breeding behavior is initiated in early spring
(generally in March) and terminates in late
May. Many of the attributes that distinguish
449
Young et al.
NEW SPECIES OF SAGE GROUSE
FIG. 2. Rectrices of Gunnison Sage-Grouse (b and d) and Sage-Grouse (a and c). Drawn from life by D.
L. Rieden.
male Gunnison Sage-Grouse from Sage-
Grouse males are sexually dimorphic traits
used during mating displays on the lek (Young
et al. 1994). Gunnison Sage-Grouse perform
their courtship displays at slower rates (Young
et al. 1994). They possess a different mating
call in which they pop their air sacs nine times
instead of twice as does the Sage-Grouse
(Young et al. 1994). Previous studies of sage-
grouse indicate that some acoustical aspects of
the mating display influence male mating suc-
cess (Gibson and Bradbury 1985, Gibson et
al. 1991). On average, only 10–15% of the
adult males breed on the lek each season (J.
R. Young, pers. obs.). Yearling and adult fe-
males breed; yearling males probably breed
rarely.
Male courtship calls of Gunnison Sage-
Grouse have been described by Young and co-
workers (1994), and recordings of males and
females have been deposited with the Library
of Natural Sounds (LNS) at the Cornell Lab-
oratory of Ornithology. In general, male Gun-
nison Sage-Grouse have mating vocalizations
that are similar in duration, but different in
structure from male mating vocalizations of
Sage-Grouse. Gunnison Sage-Grouse females
produce a variety of vocalizations on the lek;
however, they have not been compared with
vocalizations from female Sage-Grouse. Both
male and female Gunnison Sage-Grouse vo-
calize off the lek and in contexts similar to
those noted in the other species (J. R. Young,
pers. obs.). No vocalization recordings have
been obtained for either sex off the lek.
Young (1994) found that females in the
Gunnison Basin and northern Colorado avoid-
ed playbacks of male courtship vocalizations
that differed from the vocalizations of their
local population. She concluded that differ-
ences in male courtship vocalizations were
likely a barrier to mating between Gunnison
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THE WILSON BULLETIN
Vol. 112, No. 4, December 2000
FIG. 3. Lateral views of head and neck of Gunnison Sage-Grouse (lower) and Sage-Grouse (upper). Drawn
from life and photos by D. L. Rieden.
451
Young et al.
NEW SPECIES OF SAGE GROUSE
Sage-Grouse and Sage-Grouse. Thus, Gunni-
son Sage-Grouse appear to be reproductively
isolated based on male courtship vocaliza-
tions, which act as pre-mating isolating mech-
anisms. Divergence of mating behaviors cou-
pled with geographical isolation may result in
the rapid evolution of a new species through
sexual selection (Lande 1981, Kaneshiro and
Boake 1987).
GENETICS
Sequence information from 141 bp of re-
gion I of the rapidly evolving mitochondrial
control region was gathered from 201 individ-
uals of 5 Sage-Grouse and 4 Gunnison Sage-
Grouse populations within Colorado (Kahn et
al. 1999, Oyler-McCance et al. 1999). Sage-
grouse in general were found to have four
dominant haplotypes in all populations, only
one of which was found in the Gunnison
Sage-Grouse populations. The Gunnison
Sage-Grouse populations had one haplotype
that was unique. A similar distinction between
Gunnison Sage-Grouse and Sage-Grouse was
found using 4 nuclear microsatellites (Oyler-
McCance et al. 1999).
Both mitochondrial and nuclear markers re-
vealed there were no significant differences
among the Sage-Grouse populations indicat-
ing gene flow among them. Within the Gun-
nison Sage-Grouse populations, however,
most pairwise comparisons with other popu-
lations showed significant differences among
populations suggesting there is some popula-
tion differentiation, probably as a result of
their small population sizes and isolation
(Oyler-McCance et al. 1999).
Thus, DNA sequence information from the
mitochondrial and nuclear genomes supports
the hypothesis that there is a barrier to gene
flow between Gunnison Sage-Grouse and
Sage-Grouse populations. This implication is
made on the basis of two observations. First,
there are frequency differences of shared mi-
tochondrial haplotypes and shared microsat-
ellite alleles between Sage-Grouse and Gun-
nison Sage-Grouse. Second, there are 3 mi-
crosatellite alleles and 1 mitochondrial hap-
lotype that have remained unique to the
small-bodied populations, based on the cur-
rent sampling numbers.
We suggest these genetic differences are the
result of reproductive isolation that is rein-
forced by (at minimum) the behavioral isolat-
ing mechanisms discussed previously. Hence,
we conclude these are separate species ac-
cording to the biological species concept.
However, there are no fixed sequence differ-
ences between the two taxa so that based on
the molecular data alone, an interpretation that
these are species according to the phyloge-
netic species concept is obviated. The molec-
ular differences we observed between these
taxa are among the smallest observed for most
vertebrates (Avise and Walker, 1999). Avise
and Walker (1999) suggested that genealogi-
cal (phylogenetic) and reproductive traits are
intimately intertwined, as are the related bio-
logical and phylogenetic species concepts. It
appears the Gunnison Sage-Grouse provides
an example of an intermediate stage of spe-
ciation where reproductive isolation is in
place, but other molecular differences contin-
ue to diverge. Such a situation can be expect-
ed when morphological or behavioral change
occur rapidly relative to changes in alternate
haplotypes/alleles that are not related to re-
productive isolation. Based on the extreme
sexual dimorphism and the small number of
males that obtain most of the matings (Wiley
1973, Vehrencamp et al. 1989), sexual selec-
tion is likely the predominant selective force.
HABITAT AND CONSERVATION STATUS
Habitat.—Nesting, brood-rearing, and sum-
mer habitats used by Gunnison Sage-Grouse
have been described by Young (1994) and
Commons (1997). Nesting success is highest
in areas where forb and grass covers are found
below a sagebrush (15–30%) canopy (Young
1994). Average clutch size (n
5
24) is 6.8 (
6
0.7) eggs and eggs average 54.5 (
6
1.4) mm
long
3
38.0 (
6
0.7) mm diameter. Clutch and
egg sizes are within the range reported for
Sage-Grouse (Schroeder et al. 1999). In winter
Gunnison Sage-Grouse are restricted to areas
with substantial cover (15–30%) of big sage-
brush (A. tridentata vaseyana, A. t. wyomin-
gensis), black sagebrush (A. nova), and low
sagebrush (A. arbuscula) intermixed with na-
tive grasses and forbs and associated riparian
habitats (Hupp and Braun 1989). Their winter
habitat differs from Sage-Grouse; they use ar-
eas with more deciduous shrubs such as Gam-
bel oak (Quercus gambelii) and serviceberry
(Amelanchier) as well as areas invaded by pi-
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THE WILSON BULLETIN
Vol. 112, No. 4, December 2000
n˜on (Pinus) and juniper (Juniperus) at eleva-
tions of 1800–2800 m. Sagebrush leaves are
probably the principle food from November
into April, whereas forbs and insects are com-
monly eaten in summer. In disturbed and frag-
mented habitats, Gunnison Sage-Grouse for-
age and roost in cultivated fields of alfalfa,
wheat, and beans (Young 1994, Commons
1997). Detailed analyses of their diet across
seasons have not been done.
Conservation status.—The historic abun-
dance is unknown but we estimate that it was
several orders of magnitude larger than at pre-
sent based on historical documents and inter-
views. Eight populations are known, totaling
fewer than 5000 breeding birds of which few-
er than 3000 occur in the Gunnison Basin,
Colorado. Some populations are small, fewer
than 150 breeding birds and several former
populations are known to have become extir-
pated since 1980 (Braun 1995). Fewer than
150 Gunnison Sage-Grouse are known to oc-
cur in Utah. Gunnison Sage-Grouse are at risk
of extinction because of habitat loss, fragmen-
tation, and degradation (Braun 1998, Oyler-
McCance 1999). In the Gunnison Basin, the
average number of males attending leks has
declined by more than 60% since 1953 (J. R.
Young, unpubl. data). All eight small popu-
lations have high potential for inbreeding and
populations that have been examined have
low genetic diversity in the nuclear and
mtDNA genomes (Young 1994, Kahn et al.
1999, Oyler-McCance et al. 1999). A petition
has been submitted requesting listing under
the federal Endangered Species Act of 1973.
The Colorado Division of Wildlife, Bureau of
Land Management, and other agencies within
the U.S. Department of Interior, working with
local agencies, interest groups, and private cit-
izens, have developed locally derived and sup-
ported conservation plans. Some aspects of
those plans are being implemented for six
populations in Colorado. A conservation plan
is under development for Gunnison Sage-
Grouse in San Juan County, Utah, and plans
are being finalized for two of the three pop-
ulations in Colorado that lack approved plans.
Submission of this manuscript was deliberate-
ly delayed for several years to allow comple-
tion and implementation of conservation plans
to help protect the new species. With comple-
tion and implementation of useful conserva-
tion plans, it is our hope that Gunnison Sage-
Grouse will continue to exist for the foresee-
able future.
ETYMOLOGY
This new species is named Centrocercus
minimus because of its relatively small size.
The English name, Gunnison Sage-Grouse, is
derived from the general area (Gunnison Ba-
sin, Gunnison County, Colorado) where the
species was first recognized as being different
and intensively studied, and in recognition of
the effort by the local citizens who seek to
promote its conservation.
ACKNOWLEDGMENTS
Numerous individuals have been helpful with our
studies of Gunnison Sage-Grouse and we thank all
who helped with this long-term effort. We thank all
that came out with us at strange hours of the night to
trap and record data during early dawns (especially C.
L. Henkel, L. A. Higgins, J. A. Hill, D. L. Rieden, and
T. J. Swedlund) and those whose research has contrib-
uted to our knowledge of Gunnison Sage-Grouse in-
cluding M. L. Commons and S. H. Ly. We appreciate
the willingness of private landowners to work with us
in planning and implementing conservation actions de-
signed to stop and reverse the decline in distribution
and abundance of this unique species. Personnel of the
BLM, especially M. W. Stiles (Montrose) and J. D.
Almand (Washington, D.C.) were helpful with policy
issues which facilitated our work at local levels in
southwestern Colorado. Other employees of the BLM
that were particularly helpful were J. A. Capodice, H.
D. Countess, J. A. Hayes, S. J. Hayes, and S. L. Thode.
All trapping, banding, and collections were under per-
mits issued by the Colorado Division of Wildlife. The
Colorado Division of Wildlife was helpful with logis-
tics and support and we especially thank Area Man-
agers J. D. Houston and J. A. Young, and District
Wildlife Managers M. C. Coghill, P. J. Creeden, D. B.
Harper, T. K. Henry, D. B. Homan, P. B. Jones, and T.
J. Spezze. We thank D. L. Rieden and D. Radovich for
their artistic talents and J. W. Bradbury, R. D. Howard,
and S. L. Vehrencamp for advice and support. We also
thank W. G. Alther and C. R. Preston of the Denver
Museum of Natural History for advice and preparation
of the specimens. The Colorado Division of Wildlife
supported this work under Federal Aid in Wildlife Res-
toration Projects W-152-R and W-167-R. Research
support was also obtained from the Rob and Bessie
Welder Wildlife Foundation, Indiana Academy of Sci-
ence, Sigma Xi, American Museum of Natural History
Chapman Fund, Colorado Cooperative Fish and Wild-
life Research Unit, Colorado State University, Purdue
University, and Western State College. This manu-
script was improved by the reviews of R. C. Banks, J.
P. Hubbard, and an anonymous reviewer.
453
Young et al.
NEW SPECIES OF SAGE GROUSE
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... Those Sage-Grouse occurring in southwestern Colorado and southeastern Utah exhibit unique characteristics that have been considered sufficient to treat these birds as a distinct speciesthe Gunnison Sage-Grouse (C. minimus) (Young et al. 2000). Gunnison Sage-Grouse are geographically isolated from populations of Greater Sage-Grouse (C. ...
... Although the species has been distinctively different from Greater Sage-Grouse for millennia, limited research has focused on the Gunnison Sage-Grouse. Naturally, initial research on the Gunnison Sage-Grouse focused on factors describing the species, such as morphology (Hupp and Braun 1991), breeding behavior , and genetics (Oyler-McCance et al. 1999), which led to its formal recognition as a distinct species (Young et al. 2000). More recently, other studies have described various aspects of habitat (Oyler-McCance et al. 2001, Aldridge et al. 2012, movement behavior (Commons 1997), effective population size (Stiver et al. 2008), population genetics (Oyler-McCance et al. 2005, population dynamics (Davis et al. 2014(Davis et al. , 2015Stanley et al. 2015), and historical distribution (Braun et al. 2014, Braun andWilliams 2015). ...
... kg and females 0.9-1.3 kg (Young et al. 2000). The adult male has fuscous upperparts, profusely marked with drab gray and white; long and pointed rectrices with white bars; plain brown primaries; chin and throat sepia (blackish); sides of neck, breast, and upper belly whitish and slightly distended, forming a ruff; belly and undertail coverts sepia with large white spots on tips of undertail coverts; and buff thighs. ...
... Both species have been well-studied from a genetic perspective with over 25 peer-reviewed publications in the past 20 years. The earliest research began in the mid-1990s examining taxonomy and distinct populations Oyler-McCance et al. 1999;Young et al. 2000;Benedict et al. 2003). Since those early papers, the range in topics tackled by genetic studies has been broad, examining questions ranging from lek formation and mating system (Gibson et al. 2005;Semple et al. 2001;Bird et al. 2012) to detecting gene flow and identifying landscape features impacting population connectivity (Bush et al. 2011;Oyler-McCance et al. 2005a, b;Cross et al. 2016;Row et al. 2015). ...
... Sage-grouse are considered sagebrush obligate species (Beever and Aldridge 2011), depending on sagebrush throughout their entire life cycle (Patterson 1952). They require sagebrush for cover and nesting, and while they forage on sagebrush throughout the year, they rely on it exclusively for food in the winter months (Patterson 1952;Dalke et al. 1963;Wallestad et al. 1975;Braun et al. 1976;Connelly et al. 2000;Young et al. 2000). There are six main species and subspecies of sagebrush that are important for sage-grouse (described in Connelly et al. 2000), and their occurrence varies widely across the landscape due to differences in climate, soil type, topography, and disturbance (West 1983;Miller et al. 2011). ...
... Both species of sage-grouse have a polygynous mating system that has been the focus of numerous studies over many decades (Wiley 1974;Wittenberger 1978;Gibson and Bradbury 1986;Bergerud 1988;Gibson et al. 1991;Young et al. 2000). In the spring, males congregate on leks, where they engage in an elaborate strutting display to attract females. ...
Chapter
For over two decades, genetic studies have been used to assist in the conservation and management of both Greater Sage-grouse (Centrocercus urophasianus) and Gunnison Sage-grouse (C. minimus), addressing a wide variety of topics including taxonomy, parentage, population connectivity, and demography. The field of conservation genetics has been transformed by dramatic improvements in sequencing technology, facilitating genomic studies in many wildlife species. The quality and amount of data generated by genomic methods vastly exceed that of traditional genetic studies, allowing for increased precision in estimating genetic parameters of interest. Perhaps more importantly, genomic methods can provide insight into non-neutral evolution such as adaptive divergence. Here we recount the shift from genetic to genomic methods using two wildlife species of substantial conservation interest, focusing on the improved capabilities and advantages of genomic methods. For instance, reassessment of divergence in sage-grouse using genomic methods confirmed strong differentiation between the two species and revealed that a small population in the state of Washington was more genetically distinct than previously recognized. Further, new genomic resources and approaches have been used to identify a family of genes linked to local dietary adaptation suggesting that sage-grouse may possess digestive and metabolic adaptations that mitigate the effects of consuming plant secondary metabolites like those found in sagebrush. Genetic variation among populations in these gene regions is thought to be involved with local dietary adaptations, and therefore maintaining the tie between sage-grouse and the chemistry of local sagebrush may be an important management consideration. We posit that the integration of newly developed genomic resources combined with the vast wealth of ecological and behavioral data for sage-grouse has the potential to shed light on mechanistic relationships that ultimately are vital to the conservation and management of these species.
... tridentata). This relationship has been shown in numerous descriptions of sage-grouse range including reports by Bendire (1892), Judd (1905), Girard (1937), McClanahan (1940), Patterson (1952), Aldrich and Duvall (1955), Aldrich (1963), Wallestad (1975), Johnsgard (1973Johnsgard ( , 1983Johnsgard ( , 2002, Connelly and Braun (1997), Braun (1998), Schroeder et al. (1999), Young et al. (2000), and Benedict et al. (2003). Unfortunately, distribution maps for sage-grouse are usually shown at a scale that makes coordination with localized management efforts difficult. ...
... Habitats without known use by sagegrouse were excluded from the presettlement distribution of potential habitat, even if there were scattered observations or recoveries of sage-grouse. The differentiation between Gun-nison and Greater Sage-Grouse in transition zones in Utah and Colorado was addressed in earlier research and was included in these maps (Young et al. 2000). ...
... Presettlement distribution of potential habitat. Potential habitat for the Gunnison Sage-Grouse includes 46 521 km 2 distributed in central and southwestern Colorado, southeastern Utah, northwestern New Mexico, and northeastern Arizona (Fig. 1, Young et al. 2000). Regional journals in 1849 (Simpson 1964) and 1880-1882 (Bandelier 1966) did not mention sage-grouse but noted the prevalence of agriculture and the long history of settlement. ...
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Article
We revised distribution maps of potential presettlement habitat and current populations for Greater Sage-Grouse (Centrocercus urophasianus) and Gunnison Sage- Grouse (C. minimus) in North America. The revised map of potential presettlement habitat included some areas omitted from previously published maps such as the San Luis Valley of Colorado and Jackson area of Wyoming. Areas excluded from the revised maps were those dominated by barren, alpine, and forest habitats. The resulting presettlement distribution of potential habitat for Greater Sage-Grouse encompassed 1 200 483 km2, with the species' current range 668 412 km2. The distribution of potential Gunnison Sage-Grouse habitat encompassed 46 521 km2, with the current range 4787 km2. The dramatic differences between the potential presettlement and current distributions appear related to habitat alteration and degradation, including the adverse effects of cultivation, fragmentation, reduction of sagebrush and native herbaceous cover, development, introduction and expansion of invasive plant species, encroachment by trees, and issues related to livestock grazing. Distribución de Centrocercus spp. en América del Norte Resumen. Revisamos los mapas de distribución potencial precolombino y de poblaciones actuales de Centrocerus urophasianus y C. minimus en América del Norte. El mapa modificado de hábitat potencial precolombino incluyó algunas áreas omitidas de mapas anteriormente publicados, como el Valle San Luis de Colorado y el área de Jackson, Wyoming. Las áreas excluídas de los mapas modificados fueron las dominadas por hábitats forestales, alpinos y estériles. La distribución precolombina resultante para C. urophasianus abarcó 1 200 483 km2, con un territorio actual de 668 412 km2. La distribución de habitat potencial para C. minimus abarcó 46 521 km2, con un territorio actual de 4787 km2. Estos contrastes tan marcados parecen estar relacionados con la modificación y degradación del hábitat, incluyendo los efectos nocivos de la agricultura, la fragmentación de hábitat, la disminución de Artemisia spp. y otras coberturas herbáceas nativas, el desarollo, la introducción y la expansión de especies de plantas invasoras, la invasión de árboles y cuestiones relacionadas con pastoreo de ganado.
... However, it remains uncertain whether the Jackson and Gros Ventre populations were in fact connected to populations such as Pinedale for much longer periods of time prior to European settlement, similar to Gunnison sage-grouse (C. minimus ;Young et al. 2000). For example, Jackson is surrounded by high elevation forest, including multiple mountain ranges (i.e. ...
... The genetic differentiation observed with STRUCTURE ( Figure 2) and BAPS corresponds to the level I ecoregion delineation for the state of Wyoming (see Commission for Environmental Cooperation Working Group, 1997;Olson et al. 2001; Figure 1). If ecological differences are sufficient, local adaptation may further limit contemporary gene flow, eventually resulting in separate species, similar as happened with Gunnison sage-grouse (Young 2000) and red crossbill (Loxia curvirostra complex; Benkman 2003; Smith and Benkman 2007;Smith et al. 2012). Some evidence suggests that the sage-grouse in Jackson utilize different habitats than other sage-grouse populations (Chong et al. 2011), concurrent with the theory of local differences arising as a result of different ecological pressures. ...
Article
Habitat loss is well recognized as an immediate threat to biodiversity. Depending on the dispersal capabilities of the species, increased habitat fragmentation often results in reduced functional connectivity and gene flow followed by population decline and a higher likelihood of eventual extinction. Knowledge of the degree of connectivity between populations is therefore crucial for better management of small populations in a changing landscape. A small population of greater sage-grouse (Centrocercus urophasianus) exists in northwest Wyoming within the Jackson Hole valley, including Grand Teton National Park and the National Elk Refuge. To what degree the Jackson population is isolated is not known as natural dispersal barriers in the form of mountains and anthropogenic habitat fragmentation may limit the population’s connectivity to adjacent populations. Using 16 microsatellite loci and 300 greater sage-grouse samples collected throughout Wyoming and southeast Montana, significant population differentiation was found to exist among populations. Results indicated that the Jackson population was isolated relative to the other sampled populations, including Pinedale, its closest neighboring large population to the south. The one exception was a small population immediately to the east of Jackson, in which asymmetric dispersal from Jackson into Gros Ventre was detected. Both Jackson and Gros Ventre populations exhibited significantly reduced levels of neutral genetic diversity relative to other sampled populations. More work is warranted to determine the timing at which Jackson and Gros Ventre populations had become isolated and whether it was primarily due to recent habitat fragmentation or more historic processes. Due to its small population size, continual monitoring of the population is recommended with the goal of at least maintaining current population size and, if possible, increasing suitable habitat and population size to levels recorded in the past.
... As a name proposed ''as a means of temporary reference and not for formal taxonomic use as a scientific name in zoological nomenclature,'' it is excluded from the provisions of the International Code of Zoological Nomenclature under Article 1(b)(6) of the third edition (ICZN 1985) and Article 1.3.5 of the fourth edition (ICZN 1999) of the Code. The first available name is that proposed by Young et al. (2000). In formal listings, as in the citation in this Check-list, all authors of the name Centrocercus minimus should be given; in less formal listings, as in the species heading, the authorship of Centrocercus minimus can be given merely as Young et al., 2000. ...
... The first available name is that proposed by Young et al. (2000). In formal listings, as in the citation in this Check-list, all authors of the name Centrocercus minimus should be given; in less formal listings, as in the species heading, the authorship of Centrocercus minimus can be given merely as Young et al., 2000. p. 136. ...
... Over 50% of the sagebrush (Artemisia sp.) distribution has been removed or degraded Knick et al., 2013;Schroeder et al., 2004), imperiling the resident sagebrush obligate wildlife species (Anderson & Inouye, 2001). The Gunnison sagegrouse is one such sagebrush obligate species (Patterson, 1952;Young et al., 2000) impacted by the alteration of western landscapes (Oyler-McCance et al., 2001;Primack, 1993;Theobald et al., 1996). ...
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Article
Habitat fragmentation and degradation impacts an organism's ability to navigate the landscape, ultimately resulting in decreased gene flow and increased extinction risk. Understanding how landscape composition impacts gene flow (i.e., connectivity) and interacts with scale is essential to conservation decision‐making. We used a landscape genetics approach implementing a recently developed statistical model based on the generalized Wishart probability distribution to identify the primary landscape features affecting gene flow and estimate the degree to which each component influences connectivity for Gunnison sage‐grouse (Centrocercus minimus). We were interested in two spatial scales: among distinct populations rangewide and among leks (i.e., breeding grounds) within the largest population, Gunnison Basin. Populations and leks are nested within a landscape fragmented by rough terrain and anthropogenic features, although requisite sagebrush habitat is more contiguous within populations. Our best fit models for each scale confirm the importance of sagebrush habitat in connectivity, although the important sagebrush characteristics differ. For Gunnison Basin, taller shrubs and higher quality nesting habitat were the primary drivers of connectivity, while more sagebrush cover and less conifer cover facilitated connectivity rangewide. Our findings support previous assumptions that Gunnison sage‐grouse range contraction is largely the result of habitat loss and degradation. Importantly, we report direct estimates of resistance for landscape components that can be used to create resistance surfaces for prioritization of specific locations for conservation or management (i.e., habitat preservation, restoration, or development) or as we demonstrated, can be combined with simulation techniques to predict impacts to connectivity from potential management actions.
... Arguments against the BSC (Zink and McKitrick 1995; but see counter-arguments by Johnson et al. 1999) focus on its difficult application to allopatric populations, hybridizing lineages, and non-historical groups. Although the BSC may be challenging to apply at times, it can be used to evaluate the taxonomic status of populations based on multitrait analyses (Young et al. 2000) and estimated divergence times among closely related lineages relative to geographic breaks (Ramírez-Barrera et al. 2018, Venkatraman et al. 2019. Under pragmatic applications of the BSC, it is important to recognize that low levels of hybridization may occur even in well-delineated species (Toews et al. 2018(Toews et al. , 2020. ...
Full-text available
Article
Species delimitation requires a broad assessment of population-level variation using multiple lines of evidence, a process known as integrative taxonomy. More specifically, studies of species limits must address underlying questions of what limits the distribution of populations, how traits vary in association with different environments, and whether the observed trait differences may lead to speciation through reproductive isolation. While genomic data have revolutionized the process of delimiting species, such data should be analyzed along with phenotypic, behavioral, and ecological traits that shape individuals across geographic and environmental space. The integration of multiple traits promotes taxonomic stability and should be a major guiding principle for species delimitation. Equally important, however, is thorough geographic sampling to adequately represent population-level variation—both in allopatry and across putative contact zones. We discuss the importance of both of these factors in the context of species concepts and traits and present different examples from birds that illustrate criteria for species delimitation. In addition, we review a decade of proposals for species-level taxonomic revisions considered by the American Ornithological Society’s North American Classification Committee, and summarize the basis for decisions on whether to split or lump species. Finally, we present recommendations and discuss challenges (specifically permits, time, and funding) for species delimitation studies. This is an exciting time to be studying species delimitation in birds: many species-level questions remain, and methodological advances along with increased access to data enable new approaches to studying age-old problems in avian taxonomy.
... Minimum population size of Greater Sage-Grouse as of the beginning of the 2015 breeding season was thought to be approximately 424,000 individuals (WAFWA 2015). Gunnison Sage-Grouse, recognized as a distinct species only recently (Young et al. 2000), have a population estimate of <5,000 individuals (Young et al. 2015). After undergoing substantial declines in recent decades, numbers in the largest remaining population, in Colorado's Gunnison Basin, have stabilized, although the other six populations continue to decline (Young et al. 2015). ...
Preprint
A literature review of empirical research on the interactions between wind-energy development and grouse (Aves:Tetraoninae) of the North American plains and shrub-steppe.
... These include Dusky Grouse (Dendragapus obscurus) (Marsh 1931, Bailey andNiedrach 1965), Greater Sage-Grouse (Centrocercus urophasianus), (Marsh 1931, Bailey andNiedrach 1965), Gunnison Sage-Grouse (C. minimus) (Young et al. 2000), Greater Prairie-Chicken (Typanuchus cupido) (Marsh 1931, Bailey andNiedrach 1965), Lesser Prairie-Chicken (T. pallidicinctus) (Lincoln 1917), Sharp-tailed Grouse (Plains, Typanuchus phasianellus jamesi [Cooke 1897[Cooke , 1909 and Columbian, T. p. columbianus) (Marsh 1931, Bailey andNiedrach 1965), White-tailed Ptarmigan (Lagopus leucura) (Marsh 1931, Bailey andNiedrach 1965), and Ruffed Grouse (Bonasa umbellus) (Braun et al. 2003). ...
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Article
Ruffed Grouse (Bonasa umbellus) were not documented (no specimen records) in Colorado until 1988. All prior observation reports were poorly documented and were thought to be Dusky Grouse (Dendragapus obscurus) or possibly Columbian Sharp-tailed Grouse (Tympanuchus phasianellus columbianus). Interest in releasing Ruffed Grouse in Colorado was generated from outside of the State by a private individual and then by hunters within Colorado. These individuals were encouraged by The Ruffed Grouse Society to persuade staff of the Colorado Division of Wildlife to support releases of wild-trapped Ruffed Grouse in Colorado. The official position of the Colorado Wildlife Commission at that time was to not allow release of 'non-native' species unless such releases complied with the written policy that "non-native species will be introduced only when sufficient investigations are made to insure that non-native species will not have an adverse impact on a habitat that is occupied by a native species; is ecologically suitable for the environment where it will be released; will be contained within the boundaries of the state; and there is proven biological or social demand for the species.
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Article
This synthesis presents an update of a prior publication summarizing effects of management practices on greater sage-grouse. Topics include area requirements, suitable habitat, site fidelity, and species' response to fire, grazing, pesticides and herbicides, energy and urban development, and translocation. It concludes with management recommendations, and provides a ready resource of primary literature.
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Article
We studied sagebrush (Artemisia spp.) exposure above snow and topographic distribution of sage grouse (Centrocercus urophasianus) foraging sites in winter (Jan-Mar) in the Gunnison Basin, Colorado. Sage grouse feeding activity (n = 157 foraging sites) was not proportionally distributed among 5 topographic categories (P < 0.001). Most (46 and 75% of foraging sites in 1985 and 1986, respectively) feeding activity occurred in drainages and on slopes with south or west aspects. Use of slopes with north or east aspects was less than expected. Distribution of sage grouse feeding activity was influenced by topographic variation in snow depth and mountain big sagebrush (A. tridentata vaseyana) exposure above snow. During a severe winter in 1984, <10% of the sagebrush vegetation in the Gunnison Basin was exposed above snow and available to sage grouse. During milder winters in 1985 and 1986, exposure of sagebrush was 84 and 79%, respectively. We recommend that sagebrush be maintained in drainages and on slopes with south or west aspects.
Full-text available
Article
Sage Grouse (Centrocercus urophasianus) are the largest North American grouse, both in body dimen-sions and weight. Their weight differs between sexes and varies strikingly among regions and seasons (Table 1). Weight has been used as a criterion for sex determination (June 1967). However, there is little systematic information on seasonal weight change. Before weight can be assessed as a physi-ological index, a taxonomic criterion, or a factor in behavioral development the seasonal pattern of weight change must be documented. METHODS Body weights of 320 Sage Grouse captured during 1965-69 and 1,102 during 1973-76 were recorded. All grouse were captured in North Park, Colorado, the northernmost of Colorado' s four large intermon-tane parks. Elevation of sagebrush (Atiemisia spp.) lands varies from 2,400 to 2,585 m, with surrounding mountain ranges rising steeply to 3,850 m. Although birds were captured during winter, spring, and sum-mer, over 92% were caught during the breeding season (Apr.-May). Detailed capture procedures were described by Braun and Beck (1976). Birds were classed as adults (>18 months) or yearlings (<18 months) based on wear of primary feathers (Eng 1955, Beck et al. 1975). Birds were weighed on spring scales or triple-beam balances.
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Article
Sage grouse, Centrocercus urophasianus, in an isolated montane basin near Gunnison, Colorado differ in several morphological and behavioural traits from conspecifics studied in other areas of the species' range. Both sexes in Gunnison are smaller than sage grouse elsewhere, and males possess differences in feather morphology as well. The mating behaviour of male sage grouse in three populations was examined to determine whether male strut displays of Gunnison sage grouse were behaviourally distinct. Behavioural analyses revealed Gunnison males perform strut displays at a slower rate than males in the two other sage grouse populations sampled. In addition, Gunnison males' strut displays contain unique visual and acoustical aspects. The most distinguishing attributes of Gunnison sage grouse were male secondary sexual characteristics including traits that correlate with mating success in other populations. Thus, phenotypic differences observed in the Gunnison population represent a divergence in expression of traits that are likely to be influenced by sexual selection. Recent models of speciation suggest that species characterized by intense sexual selection, such as those with lek mating systems, have the potential for rapid inter-populational divergence in male traits and female preferences leading to speciation.
Article
Differentiation of both species and genera within the grouse family (Tetraonidae) has been pronounced in North America. Each of its species has become adapted to specific types of habitat. These vary greatly, from aretic tundra to northern desert scrub and humid forest of both grouse (Centrocerous urophasianus), with 2 races, to the ruffed grouse (Bonasa umbellus), with 13. The races tend to be correlated with the ecological climax area in which they live. There are a few cases in which this correlation is not obvious and racial variation seems to be entirely the result of geographical isolation. The present status of grouse depends chiefly on the extent to which modification of required habitat has taken place; the greatest changes have occurred in the grasslands and the least in the aretic-alpine areas.
Article
Nearly all of the gallinaceous birds that are native to North America are included in two taxonomic groups, the grouse-like species of the subfamily Tetraoninae, and the quail-like species of the subfamily Odontophorinae. The former represent a temperate and subarctic group of about sixteen species which collectively have a widespread distribution in the Northern Hemisphere, and over half of which are found in North America. The latter group is a strictly Western Hemisphere assemblage that collectively includes about thirty species, almost half of which occur north of the Mexico-Guatemala border. Most of the remaining quails are tropical forest birds of northern and western South America about which very little is known. Thus, evidence suggests that North America was originally doubly colonized by early gallinaceous stock; from the south by basically tropical-forest-adapted birds that have evolved into the present array of quail species, and from the north by relatively arctic-adapted forms that have given rise to the present species of ptarmigans and grouse. Convergent evolution of these two separate but related stocks has since allowed much of North America to become inhabited by birds having similar ecological adaptations and in some cases overlapping distributions. Within each of the two ancestral groups, evolutionary radiation has developed an interesting spectrum of anatomical variations, ecological adaptations, and behavioral specializations. These latter two aspects—adaptational niche variations associated with habitat differences, and behavioral variations associated with maximal reproductive efficiencies under varied climates, habitats and contacts with associated species—are the primary subjects of this book. Anatomical and physiological considerations will be given some attention in the early chapters, but the primary focus will be on the living bird in its natural environment. This complete work is 654 pages, including 140 color and black-and-white plates. The PDF file of the whole book is 48 megabytes. All chapters and species descriptions are also posted here separately, for faster downloading of specific portions.