BIOLOGICAL DATA AND HABITAT REQUIREMENTS
WILDLIFE SPECIES: Centrocercus urophasianus | Sage Grouse 



TIMING OF MAJOR LIFE HISTORY EVENTS : 
Courtship/nesting - Males gather on the lek in late February to April,
as soon as the lek is relatively free of snow.  Only a few dominant
males, usually two, breed.  Sage grouse mating behaviors, which are
complex, are summarized by Johnsgard [27].  After mating, the hen leaves
the lek for the nesting grounds.  Clutch size ranges from six to eight
eggs; incubation time is 25 to 27 days.  Sage grouse apparently have
high rates of nest desertion and nest predation [21,27].  Summarizing
data from several sage grouse studies, Gill [20] found a range of
nesting success from 23.7 to 60.3 percent, with predation accounting for
26 to 76 percent of lost nests.

Brooding - Chicks fly by 2 weeks of age, although their movements are
limited until they are 2 to 3 weeks old [54].  They can sustain flight
by 5 to 6 weeks of age.  Juveniles are relatively independent by the
time they have compeleted their first molt at 10 to 12 weeks of age
[28].

Seasonal movements - Fall movements to wintering areas are driven by
weather conditions and usually occur gradually.  After late winter or
spring lekking activity, sage grouse may move to higher elevations or
down to irrigated valleys for nesting and feeding.  Brooding ranges may
be a considerable distance from winter ranges or spring nesting grounds.
Schlatterer [46] reported that in southern Idaho, brooding grounds were
13 to 27 miles (21-43 km) from the nesting grounds.  Males may also move
long distances over the seasons.  During winter in Wyoming, Patterson
[38] recovered a male sage grouse 75 air miles (120 km) from where he
had banded it the previous summer.


PREFERRED HABITAT : 
Sage grouse are totally dependent on sagebrush-dominanted habitats [5].
Sagebrush is a crucial component of their diet year-round, and sage
grouse select sagebrush almost exclusively for cover [38].  Because sage
grouse habitat and cover requirements are inseparably tied to sagebrush,
they will be discussed together.

Winter - The best winter habitat is below snowline, where sagebrush is
available all winter [44].  Dalke and others [13] reported that
wintering grounds of sage grouse in Idaho were usually where snow
accumulation was less than 6 inches (15 cm).  In areas of deep snow,
sage grouse winter where sagebrush has grown above the snow level [2].
In winter and throughout the year, sage grouse select areas of little or
no slope.  In a Colorado study, nearly 80 percent of sage grouse winter
use of 500 square miles (1,252 sq km) of sagebrush was on less than 35
square miles (87 sq km):  on flat areas where sagebrush projected above
the snow, or on south- or west-facing sites of less than 5 percent slope,
where sagebrush was sometimes quite short but still accessible [28].  In
Montana prime wintering areas were flat, large expanses of dense
sagebrush; winter home ranges of five females in Montana varied from
2,615 to 7,760 acres (1,050-3,100 ha) during 2 different years [16].

Lekking grounds - Open areas such as swales, irrigated fields, meadows,
burns, and roadsides and areas with low, sparse sagebrush cover are used
as leks [31].  Of 45 leks, Patterson [38] reported that 11 were on
windswept ridges or exposed knolls, 10 were in flat sagebrush, 7 were in
bare openings, and the remaining 17 were on various other site types.
Leks are usually surrounded by areas with 20 to 50 percent sagebrush
cover, with sagebrush no more than 1 foot (30.5 cm) tall.  When not on
the lek, sage grouse disperse to the surrounding areas [54].  Some
females probably travel between leks.  In Mono County, California, the
home range of marked females during 1 month of the breeding season was
750 to 875 acres (300 to 350 ha), enough area to include several active
leks [9].

Nesting - Sage grouse prefer relatively tall sagebrush with an open
canopy for nesting.  Hens usually nest near the lekking grounds [46],
but some hens have been noted to fly as far as 12 to 20 miles (19-32 km)
to favorable nesting sites [20,44].  In Utah, 33 percent of 161 nests
were under silver sagebrush (Artemisia cana) that was 14 to 25 inches
(36-63.5 cm) tall, while big sagebrush of the same height accounted for
24 percent of nests [41].  In a threetip sagebrush (A. tripartata)
habitat averaging 8 inches (20 cm) in height, hens selected the tallest
plants for nesting cover.  No nests occurred where threetip sagebrush
cover exceeded 35 percent.  Similarly, Patterson [38] reported that in
Wyoming, 92 percent of sage grouse nests in Wyoming big sagebrush were
in areas where vegetation was 10 to 20 inches (25-51 cm) tall and cover
did not exceed 50 percent.  In Idaho no hens nested in areas with less
than 10 percent sagebrush cover or where sagebrush cover was greater
than 25 percent [31].

During the nesting season, cocks and hens without nests use relatively
open areas for feeding, and roost in dense patches of sagebrush [30,31].

Brooding - Sage grouse brood in open sagebrush with a forb component.
As the season progresses, they move to areas still containing green
vegetation; by August, they are often clustered near permanent watering
sites [30].  In 158 Montana locations, young brood used areas of low
plant height (9 to 15 inches [23-38 cm]) and density, while older broods
and adults used areas where plants were taller (7 to 25 inches [18-63.5
cm]) [35].

During summer and early fall, male sage grouse remain segregated from
brood and hen flocks, typically remaining with 2 to 3 miles (3.2-4.8 km)
of the lek [54].


COVER REQUIREMENTS : 
See PREFERRED HABITAT.


FOOD HABITS : 
The importance of sagebrush in the diet of adult sage grouse is
impossible to overestimate.  Numerous studies have documented its
year-round use by sage grouse [4,11,12,31,38,45,48,54,55].  A Montana
study, based on 299 crop samples, showed that 62 percent of total food
volume of the year was sagebrush.  Between December and February it was
the only food item found in all crops.  Only between June and September
did sagebrush constitute less than 60 percent of the sage grouse diet
[54].  Sage grouse select sagebrush species differentially.  Sage grouse
in Antelope Valley, California, browsed black sagebrush more frequently
than the more common big sagebrush [45].  Among the big sagebrush
subspecies, basin big sagebrush is less nutritious and higher in
terpenes than either mountain or Wyoming big sagebrush.  Sage grouse
prefer the other two subspecies to basin big sagebrush [2].

Sage grouse lack a muscular gizzard and cannot grind and digest seeds:
They must consume soft-tissue foods [54].  Apart from sagebrush, the
adult sage grouse diet consists largely of herbaceous leaves, which are
utilized primarily in late spring and summer [15].  Sage grouse are
highly selective grazers, choosing only a few plant genera.  Dandelion
(Taraxacum spp.), legumes (Fabaceae), yarrow (Achillea spp.) and wild
lettuce (Lactuca spp.) account for most of their forb intake [2,48].
Martin [35] found that from July to September, dandelion comprised 45
percent of sage grouse intake; sagebrush comprised 34 percent.
Collectively, dandelion, sagebrush, and two legume genera (Trifolium
and Astragalus) contributed more than 90 percent of the sage grouse diet.

Insects are a minor diet item for adult sage grouse.  Martin, Zim, and
Nelson [34] reported that insects comprised 2 percent of the adult sage
grouse diet in spring and fall and 9 percent in summer.  Sagebrush made
up 71 percent of the year-round diet.

In their first week of life, sage grouse chicks consume primarily
insects, especially ants and beetles [38].  Their diet then switches to
forbs, with sagebrush gradually assuming primary importance.  In a Utah
study, forbs composed 54 to 60 percent of the summer diet of juvenile
sage grouse, while the diet of adult birds was 39 to 47 percent forbs
[51].

Water:  Sage grouse apparently do not require open water for day to day
survival if succulent vegetation is available. They utilize free water
if it is available, however.  Sage grouse distribution is apparently
seasonally limited by water in some areas.  In summer, sage grouse in
desert regions occur only near streams, springs, and water holes.  In
winter in Eden Valley, Wyoming, sage grouse have been observed regularly
visiting partially frozen streams to drink from holes in the ice [11].


PREDATORS : 
Lack of recruitment has been noted in some sage grouse populations, and
predation of juvenile sage grouse has been cited as a factor in sage
grouse population decline.  Lack of adequate nesting and brooding cover
may account for high juvenile losses in many regions [29].  A decline
in preferred prey may also result in increased predation on sage
grouse.  Kindschy [29] suggested that in southeastern Oregon, a decline
in black-tailed jackrabbit (Lepus californicus) numbers may have caused
predators to switch to sage grouse as their primary prey.

Predator species:  Coyote (Canis latrans) [29], bobcat (Lynx rufus)
[3,29], badger (Taxidea taxus)[29], falcons (Falconidae) [39], and
hawks, kites, and eagles (Accipitridae) [4,14,29,40] prey on adult and
juvenile sage grouse.  Crows and ravens (Corvus spp.) and magpies (Pica
spp.) consume juvenile birds [29].

Coyote, ground squirrels (Spermophilus spp.), and badger are the most
important mammalian nest predators.  Among bird species, magpies and
ravens commonly prey on sage grouse nests [28,25,54].

Sage grouse are a popular game bird.  Sage grouse hunting is closely
regulated in those states where it is allowed, and is not generally cited
as a factor in sage grouse decline [2,8,27,28].


MANAGEMENT CONSIDERATIONS : 
Sage grouse once occurred virtually everywhere there was sagebrush.
They have declined primarily because of loss of habitat due to
overgrazing, elimination of sagebrush, and land development [23].  Sage
grouse populations began declining from 1900 to 1915, when livestock
utilization of sagebrush rangeland was heavy [38].  In the 50's and
60's, land agencies adopted a policy of aggressive sagebrush control in
order to convert sagebrush types to grassland.  Chaining, frequent fire,
and herbicide treatments reduced sagebrush by several million acres and
sage grouse numbers plummeted drastically [11,59].  Conversion of
sagebrush types to grassland has since been brought into question as a
management practice for both wildlife and livestock [27,28,45,54].  Call
[11] stated that:

     "Any land use practice which has as its objective the permanent
      elimination of sagebrush and establishment of grasses in the
      Mountain West will ultimately reduce the collective carrying
      capacity of that range for livestock, elk, mule deer, antelope,
      sage grouse, and many smaller species of wildlife."

Sage grouse have one of the lowest recruitment rates of any upland game
bird in North America.  Loss of habitat, predation, drought, and poor
weather conditions during hatching and brooding periods have been cited
as factors leading to poor recruitment [59].

Autenrieth and others [2], Braun, Britt, and Wallestad [58], Call [11],
and Dalke and others [13] provide guidelines for management of sage
grouse and their habitat.

Sage grouse have used areas planted to crested wheatgrass (Agropyron
cristatum) as lekking grounds.  Given the ability of crested wheatgrass
to replace sagebrush and forbs, however, crested wheatgrass plantings
are not recommended in sage grouse habitat [4].



REFERENCES : 
NO-ENTRY

Related categories for Wildlife Species: Centrocercus urophasianus | Sage Grouse