NESTING AND SUMMER HABITAT USE BY TRANSLOCATED SAGE GROUSE (CENTROCERCUS UROPHASIANUS) IN CENTRAL IDAHO

6 Pages·1994·3.2 MB·English

by  David D Musil

Great Basin Naturalist54(3), © 1994,pp.22S-233
NESTING AND SUMMER HABITAT USE BY TRANSLOCATED
SAGE GROUSE (CENTROCERCUS UROPHASIANUS) IN CENTRAL IDAHO
Da\id D. Musil'-, Kerr>' E Reese^ andJohnVV. Connelly^
—
Ab.stract. We translocated 196 Sage Grouse {Centrocercus urophasianus) into Sawtooth Valley, Idaho, during
March-April 1986-87toaugmentasmallresidentpopulation. Forty-fourgrouseequippedwith radiotransmitterswere
monitoredthrough springandsummer. Nestsites(n = 6)hadgreater(P = .032)horizontalcoverthan didindependent
random plots {n — 7). Duringsummer, grouseusedsites (n = 50)with tallerliveanddeadshnibheights, greatershrub
canopycover, and more ground litter(P < .009) than were foimd on dependent random plots [n — 50)50-300 m from
use sites. Distancetoedgeandmountainbigsagebrush {Artemisia tridentata vaseyana) densitybestseparateduse sites
from independent random plots in logistic regression analysis and conectly classified 64% ofthe use sites and 78% of
the independent random plots. Sage Grouse used sites that had narrower frequency distributions for many variables
thandidindependentplots(P < .04),suggestingselectionforuniformhabitat.
Key words: Centrocercus urophasianus, dispersal, habitat use. hntiie raii<ie. Idaho, radio telemetry. Sage Grouse,
translocation.
Sage Grouse have been translocated in The objective of this study was to docu-
Montana (Thompson 1946), New Mexico ment nesting and summer habitat use by Sage
(Allred 1946), Wyoming (Allred 1946, Grouse translocated into former range in cen-
Patterson 1952), Oregon (Batterson and Morse tral Idaho. We tested the hypotheses that
1948), British Columbia (Hamerstrom and habitat characteristics were similar between
Hamerstrom 1961), and Colorado (C. E. Braun sites used by translocated grouse and random
personal communication). Despite numerous sites as well as between nest and random sites.
early translocation efforts, only one study doc-
umented sui^ival oftranslocated Sage Grouse StudyArea
(Musil et al. 1993), and little is known about
habitatusebytranslocatedbirds. All springand Sawtooth Valley is at the headwaters ofthe
summer habitat-use studies (e.g., Klebenow Salmon River in central Idaho (Tuhy 1981).
1969, Oakleaf1971, Petersen 1980, Schoenberg The valley is approximately 30 km long, 3-5
1982, Dunn and Braun 1986) involved estab- km wide, and 1960-2250 m in elevation. It is
lished Sage Grousepopulations. flanked to thewestby the Sawtooth Mountains
Historically, Sawtooth Valley in central (>3200 m) and to the east by the White Cloud
Idaho supported a population of Sage Grouse Mountains (>3500 m). The periphery ofSaw-
(Autenrieth 1981). Prior to 1980, at least six tooth Valley is composed of rolling glacial
leks were active, but annual surveys by U.S.
Forest Service (USFS) and Idaho Department moraines with slopes >10°. The valley floor is
of Fish and Game personnel indicated the composed ofglacial and alluvial deposits with
breedingpopulation declined from 1981, when slopes 0-5° (Tuhy 1981).
26 birds were seen on two leks, to 1986, when Average annual precipitation is 26 cm and
only one lek was attended by one male (A. L. average annual temperature is 6.5° C. The val-
Burton, USFS, interdepartment report). leyaverages 2.5 m ofsnow, which accounts for
Although causes ofthe population decline are 85% of the annual precipitation (Tuhy 1981).
unknown, rangeland inventories conducted Sagebrush cover dominates approximateK' 125
during 1985 and 1986 suggested the available km2 (75%) of Sawtooth Valley Mountain big
habitat should support Sage Grouse (A. L. sagebrush/Idaho fescue {Festuca idahoensis) is
Burton, USFS, interdepartment report). the majorhabitat type (Tuhy 1981).
'DepartmentofFishandWildlifeResources,UniversityofIdaho,Moscow,Idaho83843.
^Presentaddress:IdahoDepartmentofFishandGame,868EastMainStreet,Jerome,Idaho83339.
3ldahoDepartmentofFishandGame,134.5BartonRoad,Pocatello,Idaho83204.
228
1994] HabitatofTranslocated Grouse 229
Wet meadows and riparian areas cover 19 dental sighting. Nest site characteristics were
km- (11%) of the valley, irrigated pastnres 19 measured after nesting efforts ceased. At each
km^ (11%), and isolated stands of lodgepole nest the number ofshrubs in contact with the
pine {Pinus contorta) 3 km^ (2%; Musil 1989). nest bowl was counted. Height of the shrub
over thebowl and area (length X width) ofthe
Methods shrub mass surrounding the nest were mea-
sured. Density ofshrubs <40 cm and >40 cm
During late March and early April 1986 tall was measured within a 2-m radius of the
and 1987, we captured 196 Sage Grouse (46 nest. A coverboard (Jones 1968) was placed in
adult females, 19 yearling females, 115 adult the nest, and horizontal cover was estimated
males, 16 yearling males) by spotlight trapping at 2 m from the nest at 0° and 45°. The board
(Giesen et al. 1982) on 11 leks from nonmigra- was also placed flat in the nest and cover at
tory populations (J. W. Connelly personal 90° was measured. Four 20-m transects were
observation) in southeastern Idaho. Capture positioned at cardinal directions intersecting
areas were at similar elevations approximately the nest, and shrub cover was measured using
144 km from Sawtooth Valley. Grouse were the line-intercept method (Canfield 1941).
classified to age and sex (Dalke et al. 1963) Shrub and grass heights were measured at5-m
and leg-banded at the capture site. Males were intervals alongthe transects.
transported in wooden crates and females To determine whether Sage Grouse were
were moved individually in modified card- selecting nest sites based on stand characteris-
boardboxes to reduce head-scalpingand other tics, we established a dependent random plot
injuries (Patterson 1952). Birds were trans- in 1987 at a random direction and distance
ported by truck to Sawtooth Valley each morn- 50-300 m from each nest site. A correspond-
ing after capture and moved by snowmobiles ing independent random plot was located by
to the release site adjacent to the last active randomly selecting two 5-digit numbers corre-
lek. Releases occurred from 19 March to 6 sponding to the last five numbers of the east
April 1986 and25 March to 1 April 1987. and north UTM coordinates covering the
We equipped 44 (22%) grouse (31 females, study area (167 km^). To find the independent
13 males) with solar-powered radio-transmit- random plot, we paced the distance along a
ters (Musil 1989, Musil et al. 1993) attached to compass line from the nearest landmark to the
ponchos (Amstrup 1980). Fifteen grouse (8 point. Only points in sagebrush habitat were
females, 7 males) were marked with radios in used for independent random plots because
1986 and 29 (18 females, 11 males) in 1987. this is the only habitat used for nestingby this
Weight of telemetry packages (<25 g) was species (Patterson 1952, Petersen 1980,
<2.2% of the mean body weight of female Wakkinen 1990, Conne—lly etal. 1991).
grouse. Daily use sites. Vegetative and topo-
We located birds at least twice per week, graphic variables were measured at sites used
equally dividing locations during the day by radio-marked Sage Grouse during May-
among three periods (Dunn and Braun 1986). July 1987. Use plots were centered at radio-
We tracked radio-marked birds from the locations and selected uniformly among daily
ground using a hand-held 4-element Yagi use patterns ofSage Grouse (Dunn and Braun
antennaand receiver(Mech 1983). 1986). Habitat characteristics were also mea-
Radio-locations were obtained bywalking a sured at dependent and independent random
15-30-m-radius circle around the signal plots as described for nest sites.
(Musil et al. 1993). We plotted radio-locations At each use site we measured vegetation
m
on aerial photographs and 7.5-minute U.S. along two parallel 15-m transects placed 8
Geological Survey orthoquadrangle topo- apart. Transects were positioned peipendicular
graphic maps overlaid with the Universal to the contour ofthe slope and centered with-
Transverse Mercator (UTM) grid system in a 60-m-radius circle for use sites. Shrub
(Lancia 1974) scaled to 100 m^/grid. canopy cover was measured by line-intercept
(Canfield 1941). Shrub density (plants/m^)
Habitat Characteristics within 0.5 m ofeach side of the transect was
—
Nest sites. Nests of translocated Sage measured, and a clinometer was used to
Grouse were located by telemetry and inci- record slopeateachvegetation site.
230 Great Basin Naturalist [Volume 54
We estimated understory cover with modi- grouse that nested in 1987 were birds released
fied Daubenmire (1959) 4 X 5-dmplots at 1.5-m in 1986; the others were released during
intervals (20 frames/site) along the transects spring 1987. Vegetation at nest sites {n = 6)
(Mosleyetal. 1986). At each Daubenmire plot, did not differ (F > .10) from dependent ran-
heights ofthe closest live and dead shrub <1 dom plots (Wilcoxon signed rank test, P > .249
m from the transectwere measured. for all values). Although average height of
Locations ofvegetation sampling sites were shrubs covering nests (x = 50.7 ± 6.7 cm) was
plotted on 7.5-minute orthoquadrangle topo- greater {P = .04) than average shrub height
graphic maps, elevations recorded, and the surrounding nests (x = 27.3 ± 4.0), there
distance to the nearest change in cover type were no differences in shrub height or cover
(i.e., pasture, riparian, wet meadow, or timber) at nest sites compared with dependent or
measuredwith an electro—nicplanimeter. independent random sites. Grouse nested at
Vegetation analysis. Dependingon nor- sites^with greater {P = .03) horizontal cover at
mality, univariate parametric or nonparametric a 45° angle to the nest (x = 86.0 ± 12.5) than
statistical tests were used for comparing equal- at independent random sites (x = 66.9 ±
ity ofboth means and variances between use 16.5).
and random sites. Separate analyses were con-
ducted for use vs. dependent random sites Daily Use Sites
(matched pairs) and between use and indepen- Between 22 May and 23 July 1987, 50 use
dent random sites using SAS (SAS Institute, sites were sampled for 15 (3 males, 12 females)
Inc. 1985) and Statistix II (Analytical Software, radio-marked grouse, with an equal numberof
Box 130204, St. Paul, Minnesota 55113) com- dependent and independent random sites.
puterprograms. Dependent random sites averaged 163 ± 16
We used logistic regression (Harrell 1985) m from use sites. Grouse used sites with more
to identify variables that best distinguished shrub canopy cover (P < .01), greater litter
Sage Grouse use from independent random cover (P < .01), and taller live and dead
sites. Maximum-likelihood estimates were shrubs (P = .00) than at dependent random
computed to determine coefficients for vari- sites (Table 1). Variance tests indicated fewdif-
ables in the predictive model. The significance ferences in frequency distributions between
level to enter and stay in the logistic regres- Sage Grouse use and dependent random sites
sion model was set at .10, and addition ofvari- (Table 1).
ables to the model was stopped once the X^ Sage Grouse used areas with flatter slopes
testofthe residual variables was no longer sig- (P < .01), fartherfrom habitat edges (P = .01),
nificant. with more litter cover (P = .00), less bare
Nonparametric tests were used to compare ground (P = .00), and greater density ofmoun-
nests with random plots because of the small tain big sagebrush (P = .04) (Table 1) than at
sample of nests (n = 6). Wilcoxon s signed independent sites. Variance tests indicated
rank test (Conover 1980) was used to compare that grouse used narrower frequency distribu-
height of the shrub covering the nest and tions of slope, elevation, live shrub canopy
average height of live shrubs along the tran- cover, bare ground, density of shrubs other
sects surrounding the nest. than sagebrush, and live shrub height (P =
We did not intentionally flush radio- .00) but wider distributions of distances to
marked grouse; thus flock composition was edge (P = .00), dead shrub canopy cover (P <
largely unknown. Occasionally, mixed-sex flocks .01), total shrub density (P = .03), and dead
were flushed, which suggested that plots used shrub height (P = .00) (Table 1).
for habitat sampling were not represented by Two variables were identified by logistic
one sex. Therefore, we did not compare habi- regression to best separate use sites from
tatuseby male and female grouse. independent random sites. Distance from
edge and mountain big sagebrush density cor-
Results rectly classified 64% ofthe use sites and 78%
of the independent random sites. The proba-
Nest Sites
bility that a site would be classed as a use site
At least one translocated Sage Grouse nest- increased as distance from habitat edge and
ed in 1986 and six nested in 1987. Two ofthe densityofmountainbigsagebrush increased.
I
1994] HabitatofTranslocated Grouse 231
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t- 00 LD O;b tC-O~; -oHi o-iq- 0od0 pCO -H ^ o o
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— —
05 (
232 Great Basin Naturalist [Volume54
Discussion Ratti et al. (1984:1193) tested variances
between Spruce Grouse {Dendragapiis canaden-
Nest Sites sis) use sites and random plots and stated that
All nests were under sagebrush, similar to "these differences indicated a preference for
findings for many established populations sites having habitat characteristics with less
(Patterson 1952, Klebenow 1969, Wallestad variation than the general environment. "
and Pyrah 1974, and Petersen 1980) but some- Similarly, translocated Sage Grouse used nar-
what different from Sage Grouse nesting in rower ranges for several microhabitat charac-
southeastern Idaho (Connelly et al. 1991). No teristics, both topographic and structural,
differences were detected between nest sites compared with habitat available throughout
and dependent plots in the same stand of the study site. However, within a stand of
sagebrush, but hens did nest under shrubs sagebrush, translocated grouse selected habi-
that were taller than shrubs surrounding the tat with greater-than-average values rather
nest. These findings are similar to those than narrowerfrequencydistributions.
reported by Wallestad and Pyrah (1974) and Translocated Sage Grouse were not associ-
Petersen (1980) for established populations. ated with edges ofcover types as was reported
However, Wakkinen (1990) reported that Sage forgrouse in Colorado (Dunn and Braun 1986).
Grouse in southeastern Idaho nested under Grouse in Sawtooth Valley were associated
taller shrubs with a larger area than shrubs in with greater-than-average structural charac-
the same stand. Hens may select tall plants teristics ofsagebrush within a stand (i.e., taller
and clumps of shrubs for nest sites because brush and greater canopy cover). This sug-
these provide more visual obstruction to gests that variability in habitat structure not
predators. only among but also within stands of sage-
We detected few differences in vegetation brush is important to Sage Grouse by provid-
between nest sites and independent random ing adequate habitat during different seasons
sites. Wakkinen (1990) reported similar find- andfordiurnal uses (Dunn and Braun 1986).
ings and suggested this indicated an abun- Characteristics of nesting and summer
danceofsuitable nestinghabitat. habitats used by translocated grouse within
Saw1:ooth Valleywere generally similarto those
Daily Use Sites reported for established Sage Grouse popula-
Translocated Sage Grouse in Sawtooth tions in many parts ofthe species' range. This
Valley used sites with greater physical similarity suggests that translocations of Sage
obstruction than at dependent random sites, Grouse, if carefully planned, are a feasible
and these may have provided more conceal- method ofaugmenting or reestablishing Sage
ment from predators. Grouse use sites also Grouse populations (Musil et al. 1993).
had greater litter cover, which may be related Patterson (1952) concluded that restoration of
to shrub cover and live shrub height as well as relatively small Sage Grouse populations by
insect abundance (Patterson 1952, Johnson translocation was not effective because of the
and Boyce 1990). birds' tendency to disperse from the release
In a comparison of summer use sites with site. Contrary to Patterson's (1952) findings.
independent random plots, grouse used flatter Sage Grouse translocated into the Sawtooth
sites near the center ofthe valley rather than Valley remained near the release site (Musil et
the rolling glacial moraines along the perime- al. 1993). Dispersal of these birds may have
ter. The central part ofthe valley has extensive been greatly reduced because they were
stands of mountain big sagebrush, whereas released during the breeding season, into the
mixtures of sagebrush and antelope bitter- relatively insular and isolated Sawtooth Valley,
brush {Purshia tridentata) occur on the and, perhaps most importantly into an area
moraines. Areas used by grouse had little with adequate springand summerhabitat.
interspersion ofhabitat edges when compared
to sagebrush along the perimeter ofthe valley. AcKNOWLEDGMENTS
The perimeter had narrow peninsulas ofsage-
brush on steeper slopes that extended into We thank T L. Parker, G. D. Power, M. D.
lodgepole pine timber. These sites were not Scott, and J. E. Wenger for help with fielWd-
usedbyradio-marked Sage Grouse. work. We also appreciate the help of G.
1994] HabitatofTranslocated Grouse 233
Gadwa and B. R. Snider during releases. R. D. Jones, R. E. 1968. A board to measure cover used by
Guse entered data, and R. L. Crabtree and Prairie Grouse. Journal ofWildlife Management 32:
G. D. Hayward assisted in data analysis. 28-31.
Klebenow, D. a. 1969. Sage Grouse nesting and brood
Reviews by C. E. Braun, T. P Hemker, and an habitat in Idaho. Journal ofWildlife Management
anonymous referee improved earlier drafts of 33:649-662.
this manuscript. This is Gontribution No. 707 Lu-KNCLA, R. A. 1974. Auniversal grid system formaploca-
of the Idaho Forest, Wildlife and Range tions.WildlifeSocietv'Bulletin2:72.
Experiment Station and Federal Aid in Mech, L. D. 1983. Handbook ofanimal radio tracking.
UniversityofMinnesotaPress, Minneapolis. 197pp.
Wildlife Restoration ProjectW-160-R-15. Mosley, J. C, S. C. Bunting, and M. Hironaka. 1986.
DeteiTuiningrangeconditionfrom frequencydatain
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JournalofWildlifeManagement54:89-91. Received7October1992
AcceptedISJanuary1994