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Sage Grouse Response to Pinyon-Juniper
Management
Michelle L. Commons
Richard K. Baydack
Clait E. Braun
Abstract-The response of Gunnison sage grouse (Centrocercus
minimus) to management of pinyon-juniper (Pinus edulis Juniperus spp.) was studied in southwestern Colorado during
1994 through 1997. Near Crawford, CO, numbers of male sage
grouse using leks within 100 m of live pinyon-juniper were depressed because of increased raptor presence and predation associated with coniferous trees/shrubs. Removal, by cutting, of pinyon-juniper trees/shrubs in association with brush-beating to
reduce height of mountain big sagebrush and deciduous brush
resulted in doubling numbers of male sage grouse counted on
treatment leks in years 2 and 3 posttreatment. Clearing of young
age classes of pinyon-juniper that have spread into sagebrush
shrub-steppe appears to have great merit for enhancing sage
grouse use of treated areas through increased s"urvival, productivity, and recruitment. This is especially significant in management
of small populations of sage grouse in highly fragmented habitats
which may be locally threatened with extirpation.
Sage grouse (Centrocercus spp.) are dependent upon
sagebrush (Artemisia spp.) shrub- steppe throughout their
distribution in western North America (Patterson 1952).
While exact composition of the original sagebrush shrubsteppe is unknown, both grazing by wild ungulates and fire
commonly occurred, especially in higher preci pi tation zones.
Grazing of this habitat type increased following settlement
resulting in more bare mineral soil. At the same time, fire
frequency has generally decreased although intensity has
increased in some areas (Bunting 1994). Primarily because
of these 2 factors, seedlings of pinyon pine (Pinus spp.) and
juniper (Juniperus spp.) have become established in sagebrush-dominated lands in the last 40-60 years.
Populations of sage grouse have declined in many areas
of their former range (Connelly and Braun 1997). These
declines are most notable where population size is constrained by habitat limitations including loss, fragmentation, and degradation of sagebrush-dominated ecosystems.
Extinctions of local populations of sage grouse have occurred, especially at the periphery of the original distribution (Johnsgard 1973, Braun 1995).
In: Monsen, Stephen B.; Stevens, Richard, comps. 1999. Proceedings:
ecology and management of pinyon-juniper communities within the Interior
West; 1997 September 15-18; Provo, UT. Proc. RMRS-P-9. Ogden, UT: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research
Station.
Michelle L. Commons and Richard K. Baydack are with the Natural
Resources Institute, University of Manitoba, Winnipeg, Manitoba, Canada
R3T 2N2. Clait E. Braun is with the Colorado Division of Wildlife, 317 West
Prospect Road, Fort Collins, CO 80526.
238
Management of sagebrush-dominated habitats is necessary if viable populations of sage grouse are to persist. Enhancement of habitats to benefit sage grouse will require
management prescriptions and experiments to learn if treatments result in increased population size and/or distribution.
The objective ofthis paper is to describe apparent sage grouse
population response to pinyon-juniper treatment.
Study Area
The area studied is in northwest Montrose County, Colorado between the town of Crawford and the Black Canyon
ofthe Gunnison National Monument. Sage grouse occur on
lands administered by the Bureau of Land Management
and National Park Service, with substantial areas in private ownership. Dominant vegetation types include sagebrush (A. tridentata vaseyana, A. nova), pinyon-juniper,
and mountain brush (Quercus gambelii, Amelanchier spp.,
Symphoricarpos spp.) with frequent intermixing of habitats depending upon elevation, aspect, slope, and past
vegetation treatments (including grazing by domestic livestock and wild ungulates) (Commons 1997).
Methods
Numbers of male sage grouse on previously «1994)
located leks were counted in 1994 (pretreatment), 1995 (1year posttreatment) and 1996-97 (2-3 years post treatment) during April and May at 7-10 day intervals. Searches
for sage grouse mortalities were made periodically throughout the display season by walking lek sites and adjacent
habitats. Sage grouse were trapped at night (Giesen and
others 1982) where they roosted on or near leks. Radio
transmitters affixed by elastic cord or plastic collars were
attached to selected sage grouse. Radio-marked birds were
systematically followed to identify habitats used. Short
«1m) pinyon-juniper trees, sagebrush, and associated deciduous shrubs were brush beat with a tractor-drawn rotary mower. Taller (>1m) trees were cut using a chain saw
with limbs and stems being scattered. Brush beating was
initiated in August 1994 with additional sites being treated
in September - October 1996. Hand cutting oftrees near lek
sites occurred as time permitted in fall and early winter
1994, and continued away from lek sites into 1997.
Results
Three leks were active in 1994-95 and 1996-97 (table 1).
No new or unknown active lek sites were found during the
USDA Forest Service Proceedings RMRS-P-9. 1999
Table 1-Peak counts of male sage grouse on leks, Fruitland Mesa,
Colorado, 1994-95 vs. 1996-97.
Lek
1994
1995
1996
1997
Dam
Range Cone
Section 35
Totals
3
11
8
22
6
9
6
21
18
19
9
46
13
20
8
41
study period. Total males counted increased from 21-22 (199495) to a 2-year average of 43 (1996-97). This doubling in
number of males counted primarily occurred at 2 sites where
removal of pinyon-juniper was most pronounced. Mortality
searches at lek sites in 1994 located the remains of 7 male
sage grouse. No mortality searches were conducted in 1995
and no mortalities were found at lek sites in 1996-97.
Twelve sage grouse were captured and fitted with radio
transmitters in 1996. Habitats used by these birds indicated avoidance of pinyon-juniper except during September - November when sage grouse extensively used sagebrush-dominated areas with scattered trees 22 m in height
(table 2). Pinyon-juniper trees were avoided from June
through August when sage grouse selected disturbed areas
(burned, disked, rotochopped) that had an abundance of
succulent forbs.
Discussion -------------------------------The apparent size of the sage grouse population on
Fruitland Mesa as measured by counts of males on leks
doubled between 1994-95 and 1996-97. This increase was
believed to have resulted from decreased mortality of males
during the breeding season and improved survival of both
males and females. Prior to treatment (cutting of pinyonjuniper trees), raptors were observed perching and hunting
from trees adjacent to lek sites and all documented mortalities were attributed to raptor..s. However, effects of cutting
of pinyon-juniper trees were confounded as sagebrush at
lek sites was also beat thereby increasing the ability of sage
grouse to detect predators at greater distances.
Sage grouse clearly avoided pinyon-juniper trees during
the breeding and summer periods. Studies elsewhere in
Colorado indicate avoidance of pinyon-juniper trees throughout the year. At Fruitland Mesa, invasion ofpinyon-juniper
trees in the last 30-60 years has reduced the amount of area
where trees do not occur. At present, there are few areas,
outside ofthose treated in this study, where pinyon-juniper
trees do not occur.
We do not know if increased survival of males at leks
translates to increased survival of females as counts of
females at leks are problematic because of short, irregular
attendance periods. Our observations of hens and hens
with broods during other field activities in this area suggest
the population markedly increased between 1994-95 and
1996-97. Whether the apparent increase can be sustained
or further enhanced is not known. It is also remarkable the
sage grouse population apparently responded quickly to
treatments designed to immediately resolve a local problem. Outside of predation, mortality of this population
appears low as no hunting is allowed and primary roads do
not traverse the area. This small, isolated population appears to be habitat limited. Removal ofpinyon-junipertrees
could increase usable habitat size by at least 100 percent.
Acknowledgments _ _ _ _ _ __
This study was funded by the Colorado Division of Wildlife through Federal Aid in Wildlife Restoration Project
W-167-R and the Montrose District of the Bureau of Land
Management. We thank the private landowners for access
to their land and support for treatments in their grazing
allotments. We especially thank D. D. Homan and P. D.
Jones of the Colorado Division of Wildlife and R. D. Welch
of the Bureau of Land Management for advice, technical
support, and assistance throughout the study.
References __________
Braun, C. E. 1995. Distribution and status of sage grouse in
Colorado. Prairie Nat. 27: 1-9.
Bunting, S. C.1994. Effects offire onjuniperwoodland ecosystems
in the Great Basin. In: S. B. Monsen and S. G. Kitchen, comps.
Proceedings-ecology and management of annual rangelands.
Gen. Tech. Rep. INT-GTR 313. Ogden, UT: U. S. Department of
Agriculture, Forest Service, Intermountain Research Station:
53-55.
Commons, M. L. 1997. Movement and habitat use by Gunnison
sage grouse (Centrocercus minimus) in southwestern Colorado.
M.N.R.M. Practicum, Univ. Manitoba, Winnipeg. 108 pp.
Connelly, J. W., and C. E. Braun. 1997. Long-term changes in sage
grouse Centrocercus urophasianus populations in western North
America. Wildl. Biol. 3: 229-234.
Giesen, K. M., T. J. Schoenberg, and C. E. Braun. 1982. Methods for
trapping sage grouse in Colorado. Wildl. Soc. Bull. 10: 224-231.
Johnsgard, P. A. 1973. Grouse and quails of North America. Univ.
Nebraska Press, Lincoln. 553 pp.
Patterson, R. L. 1952. The sage grouse in Wyoming. Sage Books,
Inc., Denver, CO. 341 pp.
Table 2-Distance (m) of radio-marked sage grouse from pinyon/juniper trees
June- November 1996, Fruitland Mesa, Colorado.
Distance
Jun
(22)
m
_ ...
<50
50-100
>100
14
4
82
_---_
Jul
(27)
............
15
0
85
Aug
(16)
Jun-Aug
(65)
Sep
(16)
------- Percent of locations
6
6
88
12
3
85
50
12
38
Oct
(6)
.....
_---_
100
0
0
Nov
(7)
~
2 m tall,
Sep-Nov
(29)
.............. - ... - ...
29
0
71
_--
55
7
38
( ) =number of relocations of radio-marked sage grouse.
USDA Forest Service Proceedings RMRS-P-9. 1999
239