AN ABSTRACT OF THE THESIS OF
Michael W. Byrne for the degree of Master of Science in Wildlife Science
presented on February 7, 2002.
Title: Habitat Use by Female Greater Sage Grouse in Relation to Fire at Hart
Mountain National Antelope Refuge, Oregon.
Abstract approved:
0 J'_' 4
.
The United States Fish and Wildlife Service currently uses fire as a
management tool to improve Greater Sage Grouse (Centrocercus urophasianus
Bonaparte) nesting and brood-rearing habitat at Hart Mountain National Antelope
Refuge (HMNAR) in S.E. Oregon. Previous studies at HMNAR revealed use of
burned areas by sage grouse throughout the breeding season, but quantitative
evaluation of breeding-season habitat use in relation to burned areas was
unavailable. Further, the effects of prescribed fire and wildfire on sage-grouse
habitat use and habitat selection are poorly understood and controversial. I
evaluated a comprehensive database of all prescribed fire and wildfire data (19472000) and sage-grouse breeding-season habitat data (1989-2000) as a means to
evaluate and quantify the temporal and spatial effects of habitat use by female sagegrouse relative to burned areas.
Nesting, brood-rearing, and broodless females generally avoided 89%, 89%,
and 77%, respectively, of available burned habitats; unburned habitats were
typically used. All 5 nests in burns < 20 years old were unsuccessful, but nesting
success in >20 year-old burns (29%, n = 6/21) and unburned areas (28%, n =
49/177) was similar. When burned habitats were used, they were typically mid- to
late-successional mountain big sagebrush burns. Age of burn, and the resultant
return of the shrub (i.e., sagebrush) component, was most commonly associated
with use of burned areas by nesting and brood-rearing females.
Fire in areas with higher biotic potential (in terms of soil
productivity/structure, floral diversity, and precipitation), such as mountain big
sagebrush [A. t. Nutt. var. vaseyana (Rybd.) Beetle] cover types where the shrub,
herbaceous, and invertebrate components have returned, may provide favorable
habitat for limited nesting, brood-rearing, and broodless female use. However, in
areas with generally lower biotic potential, such as low sagebrush (A. arbuscula
Nutt.) and Wyoming big sagebrush (A. tridentata Nutt. var. wyomingensis Beetle &
Young) cover types, fire seemingly provided no apparent value in terms of nesting,
brood-rearing, and broodless female use. Although future research may further
elucidate burned habitat use trends, managers should be cautious in the use of
prescribed fire in sage grouse habitats.
© Copyright by Michael W. Byrne
February 7, 2002
All Rights Reserved
Habitat Use by Female Greater Sage Grouse in Relation to Fire at Hart Mountain
National Antelope Refuge, Oregon
by
Michael W. Byrne
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
Presented February 7, 2002
Commencement June 2002
Master of Science thesis of Michael W. Byme presented on February 7, 2002
APPROVED
Ma' r Professor, representing Wildlife Science
Head of Department of Fisheries and Wildlife
I understand that my thesis will become part of the permanent collection of Oregon
State University libraries. My signature below authorizes release of my thesis to
any reader upon request.
Michael W. Byrne, Author
ACKNOWLEDGEMENTS
In pursuit of any goal, support and cooperation takes many forms and
makes the endeavor much more productive, but most importantly, more enjoyable.
I have had the fortunate opportunity to work with several agencies and individuals I
would like to thank. This project would not have been possible without the longterm cooperation, financial and logistical support of the Sheldon and Hart
Mountain Refuge Complex of the U.S. Fish and Wildlife Service and the financial
support from the Oregon Department of Fish and Wildlife. It has been a pleasure
working closely with a group I admire and respect. In particular, I would like to
thank Mike Nunn, Steve Clay, Mike Dunbar, Marty Bray, Chris Farinetti, and
Andy Goheen for your advice, support, and foresight; Marty Bray for your field
mentorship, countless hours of help, advice, wit, and friendship; Jen Ballard for
your help, advice, and good weather; Mark Giordano for your help and poker
change. Gina Barr and Alicia Winters for your knack for making things run
smoothly; and Jeff Jaeger and Doug Leehmann for somehow fixing everything I
destroyed without a complaint, at least to me.
I would like to extend an enormous amount of gratitude to Dr. John
Crawford, my major professor and mentor. Your tutelage, guidance, advice, and
encouragement facilitated a graduate experience that instilled an attitude of
productivity, objectivity, and cooperation that will persist throughout my career. I
consider myself very lucky to have worked with such a phenomenal researcher,
ecologist, and individual, and I wish you the best of health.
I would also like to thank my field assistants: Sean Kiffe, Nolan Lewis,
Larry Butcher, Marshall Lipps, and Matt Wilson. Your dedication, enthusiasm,
and motivation was beyond compare and I am honored to have had the opportunity
to work with you. I sincerely appreciate all of your efforts in helping me achieve
my goals. Your constant entertainment value was an added benefit.
I am very grateful to those at OSU that have helped me along the way. A
special thanks to my committee members, Dr. Eric Forsman and Dr. Doug Johnson.
I appreciate your advice, guidance, and support, and the opportunity to benefit from
your wealth of knowledge and experience. Thank you Lavon Mauer and Ellen
Holsberry for keeping me from being too much trouble, or at least making me feel
that way; Charlotte Vickers for your guidance; Dr. Rick Miller for sharing your
knowledge of sagebrush-steppe ecology, Dr. Dave Pyke for logistical support, and
special thanks to Norman Swanson for your help with the Hart Mountain fire
history. I sincerely appreciate the help of Dawn Davis, Mike Pope, Mike Gregg
and Jay Welch for your excellent advice and assistance both in the field and in the
office, and to Mike Gregg, Marty Drut, Anita DeLong, Kreg Coggins, and Norman
Swanson for data collection at Hart Mountain over the years.
Finally, very special thanks to my family. I appreciate your well-concealed
suffering through my long-winded and overly detailed banter about sage grouse and
sagebrush ecology, often devoid of any real entertainment value. You have always
been a constant from which I draw strength to overcome challenges and achieve
goals. This work would never have been possible without your love and support,
which I consider myself incredibly fortunate to have.
TABLE OF CONTENTS
Page
INTRODUCTION
1
METHODS AND MATERIALS
7
Study Area
7
Trapping and Monitoring
11
Habitat Sampling
13
GIS Database
13
Data Analysis
16
RESULTS
20
Nesting
20
Brood-rearing
24
Broodless Females
29
DISCUSSION
32
LITERATURE CITED
38
APPENDICES
46
LIST OF FIGURES
Figure
1.
2.
3.
4.
5.
Page
Location of Hart Mountain National Antelope Refuge, Lake
County, OR.
8
Cover type classifications at Hart Mountain National
Antelope Refuge, Lake County, Oregon.
9
Mean age of burned areas available to radio-marked nesting
female sage grouse as a function of use response at Hart
Mountain National Antelope Refuge, Lake County, Oregon,
1989-2000. S - Selected, P - Proportional Use, L - Less
than Available, A- Avoided.
23
Mean age of burned areas available to radio-marked
brooding female sage grouse as a function of use response
at Hart Mountain National Antelope Refuge, Lake County,
Oregon, 1989-2000. S - Selected, P - Proportional Use, L Less than Available, A- Avoided.
27
Mean age of burned areas available to radio-marked
broodless female sage grouse as a function of use response
at Hart Mountain National Antelope Refuge, Lake County,
Oregon, 1989-2000. S - Selected, P - Proportional Use, L Less than Available, A- Avoided.
31
LIST OF TABLES
Table
1
Page
Potential for misclassification of locations in burned and
unburned habitats; radio-marked female sage grouse at Hart
Mountain National Antelope Refuge, Lake County, Oregon,
1989-2000.
15
Number of nest, brood, and broodless locations and number
of radio-marked female sage grouse at Hart Mountain
National Antelope Refuge, Lake County, Oregon, 1989-
3.
4.
5.
6.
7.
2000.
17
Sage grouse habitat characteristics (% cover) in a 1954
mountain big sagebrush burn (Degarmo Canyon Wildfire)
and unburned mountain big sagebrush at Hart Mountain
National Antelope Refuge, Lake County, Oregon, 1999.
20
Use of burned areas by radio-marked nesting female sage
grouse during the breeding season at Hart Mountain
National Antelope Refuge, Lake County, Oregon, 19892000. Mean age of burns in each use category is also
indicated.
21
Use of burned cover types by nesting female sage grouse at
Hart Mountain National Antelope Refuge, Lake County,
Oregon, 1989-2000. Mean age and number of bums in each
category is also indicated.
22
Habitat components of sage grouse nest sites in recently
burned areas (< 20 years-old), old burns (> 20 years-old),
and unburned areas at Hart Mountain National Antelope
Refuge, Lake County, Oregon, 1989-2000.
24
Use of burned areas by radio-marked brooding female sage
grouse during the breeding season at Hart Mountain
National Antelope Refuge, Lake County, Oregon, 19892000. Mean age of burns in each use category is also
indicated.
25
LIST OF TABLES (Continued)
Table
8.
9.
10.
11.
Page
Use of burned cover types by brooding female sage grouse
at Hart Mountain National Antelope Refuge, Lake County,
Oregon, 1989-2000. Mean age and number of burns in each
category is also indicated.
26
Habitat components of sage grouse brood sites in recently
burned areas (< 20 years-old), old burned areas (> 20 yearsold), and unburned areas at Hart Mountain National
Antelope Refuge, Lake County, Oregon, 1989-2000.
28
Use of burned areas by radio-marked broodless female sage
grouse during the breeding season at Hart Mountain
National Antelope Refuge, Lake County, Oregon, 19892000. Mean age of burns in each use category is also
indicated.
30
Use of burned cover types by broodless female sage grouse
at Hart Mountain National Antelope Refuge, Lake County,
Oregon, 1989-2000. Mean age and number of burns in each
category is also indicated.
30
LIST OF APPENDICES
Appendix
A.
B.
C.
Page
Fire events at Hart Mountain National Antelope Refuge,
Lake County, OR, 1947-2000.
47
Number and type of fire events and types at HMNAR,
1947-2000.
49
Percentage of burned area within utilization distribution
estimates generated for pooled individual radio-marked
female sage grouse at Hart Mountain National Antelope
Refuge, Lake County, Oregon, 1989-2000.
50
Habitat selection of low sagebrush cover types by radiomarked nesting female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 1989-
50
2000.
E.
Habitat selection of mountain big sagebrush cover types
by radio-marked nesting female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 1989-
50
2000.
F.
G.
H.
Habitat selection of other cover types by radio-marked
nesting female sage grouse with Bailey simultaneous
confidence intervals at HMNAR, 1989-2000.
51
Habitat selection of Wyoming big sagebrush cover types
by radio-marked nesting female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 19892000.
52
Habitat selection of burned cover types by radio-marked
nesting female sage grouse with Bailey simultaneous
confidence intervals at HMNAR, 1989-2000.
52
Habitat selection of low sagebrush cover types by radiomarked brooding female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 1989-
53
2000.
LIST OF APPENDICES (Continued)
Appendix
J.
K.
L.
N.
0.
P.
Q.
R.
Page
Habitat selection of mountain big sagebrush cover types
by radio-marked brooding female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 19892000.
53
Habitat selection of other cover types by radio-marked
brooding female sage grouse with Bailey simultaneous
confidence intervals at HMNAR, 1989-2000.
54
Habitat selection of Wyoming big sagebrush cover types
by radio-marked brooding female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 19892000.
54
Habitat selection of burned cover types by radio-marked
brooding female sage grouse with Bailey simultaneous
confidence intervals at HMNAR, 1989-2000.
55
Habitat selection of low sagebrush cover types by radiomarked broodless female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 19892000.
55
Habitat selection of mountain big sagebrush cover types
by radio-marked broodless female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 19892000.
56
Habitat selection of other cover types by radio-marked
broodless female sage grouse with Bailey simultaneous
confidence intervals at HMNAR, 1989-2000.
56
Habitat selection of Wyoming big sagebrush cover types
by radio-marked broodless female sage grouse with Bailey
simultaneous confidence intervals at HMNAR, 19892000.
Habitat selection of burned cover types by radio-marked
broodless female sage grouse with Bailey simultaneous
confidence intervals at HMNAR, 1989-2000.
57
57
I dedicate this thesis to my mother, Beverly C. Byrne,
and to my grandmother, Elizabeth H. Kunkel
Habitat Use by Female Greater Sage Grouse in Relation to Fire at Hart Mountain
National Antelope Refuge, Oregon.
INTRODUCTION
The Greater sage grouse (Centrocercus urophasianus Bonaparte), a once
abundant sagebrush-steppe obligate, has decreased in abundance throughout its
range in the western United States. Crawford and Lutz 1985 estimated the
number of sage grouse in Oregon declined 60% since 1940. These changes
resulted primarily from the loss of habitat through sagebrush (Artemesia L. spp.)
control programs, agricultural activities, and altered fire regimes (Dalke et al.
1963, Braun et al. 1977, Johnsgard 1983, Crawford and Lutz 1985, Drut et
al. 1994a). Crawford and Lutz (1985) found that estimates of sage grouse
productivity in Oregon declined and survival has varied substantially since the
1950's.
Because of sage grouse population declines, the species has been
petitioned for Threatened or Endangered status under the Endangered Species Act
of 1973 in Colorado, Utah, and Washington. Crawford (1982) determined that
the population decline was unrelated to harvest, and Crawford and Lutz (1985)
suggested that the population decline was a consequence of poor nesting and
brood-rearing habitat. Consequently, management of sage grouse habitats will be
critical for the recovery of sage grouse populations.
2
During the early 19th century, increased settlement of the Great Basin by
American pioneers brought about the introduction of exotic herbivores and plants,
cultivation of extensive areas, and suppression of natural wildfires (Miller 1989,
Miller and Eddleman 2000). These changes, in conjunction with climatic
fluctuations, resulted in alterations in plant composition and community structure
(Willis et al. 1993, Gruell 1995, Miller and Eddleman 2000). Sage grouse
declines coincided with increased utilization of rangelands for grazing and
agricultural activities from 1900 to 1915 (Patterson 1952). As a result, many
rangeland habitats became dominated by a dense sagebrush overstory with
corresponding decreases in grass and forb components (Vale 1974, Miller 1989,
Pyle and Crawford 1996). Although high densities of sagebrush (>25%) may
improve wintering habitat for sage grouse by increasing winter food, spring and
summer habitats have deteriorated by a reduction in the herbaceous component
that provides nesting cover and key food forbs (Sime 1991). Gruell (1995)
indicated that the exclusion of fire in sagebrush habitats has affected plant
succession and composition, resulting in shrub-dominated stands at the expense of
the herbaceous component. Furthermore, altered fire regimes have resulted in the
expansion of western juniper (Juniper occidentalis Hook.) woodlands, also
depleting the shrub and herbaceous understory (Miller and Rose 1995).
A fundamental concept in sage grouse management is to provide a balance
of sagebrush, grasses, and forbs necessary for successful fulfillment of all life-
history needs throughout the year (Connelly et al. 2000b). Prescribed fire has
3
been suggested as a means to rehabilitate shrub-dominated sagebrush habitats
(Frandsen 1985, Bunting et al. 1987). The importance of the herbaceous
component during the prenesting, nesting, and brood-rearing periods has been
well documented (Barnett and Crawford 1994, Drut et al 1994a, Drut et al 1994b,
Gregg et al. 1994, DeLong et al. 1995). In addition, prescribed fire may improve
habitat quality for sage grouse (Klebenow 1985, Bunting et al. 1987) and create
successionally variable habitats (Laycock 1991). Klebenow (1972) and Gates
(1983) indicated that prescribed fire patterns that resulted in a mosaic would,
ideally, create spatial diversity and habitat juxtapositions that could enhance sage
grouse habitat use.
The use of prescribed fire as a management tool for sage grouse habitat is
controversial (Dalke et al. 1963, Braun et al. 1977). Specific concerns relate to
removal of sagebrush to manage for sagebrush obligate species, and the unknown
reestablishment rates of sagebrush following fire. In presettlement times, fire
return intervals were typically 100 - 200 years in low sagebrush (A. arbuscula
Nutt.) communities, 50 - 100 years in Wyoming big sagebrush (A. tridentata Nutt.
var. wyomingensis Beetle & Young) communities, and 12 - 25 years in mountain
big sagebrush [A. t. Nutt. var. vaseyana (Rybd.) Beetle] communities (Wright and
Bailey 1982, Miller and Rose 1999). The amount of time for sagebrush to return
to a burned area can be quite substantial, site specific, and variable (Watts and
Wambolt 1996, Miller and Eddleman 2000, Nelle et al 2000). A broad or over-
4
exuberant use of fire may negatively affect sagebrush ecosystems (Fischer et al.
1996, Nelle et al 2000)
Prescribed fire has the potential to increase grasses and forbs in sagebrush
habitats (Pyle and Crawford 1996), but Miller and Eddleman (2000) found that
the outcome of fire is related to sagebrush species/subspecies, site potential, site
condition, plant groups, and bum pattern and size. Prescribed fire in mountain big
sagebrush stands in Wyoming produced twice the amount of perennial forbs in
burned areas than in unburned areas for 3 years post-burn in a relatively mesic
environment (Cook et al. 1994). Martin (1990) observed an increase in forbs after
fire in a mesic Idaho site, and Pyle and Crawford (1996) found that prescribed fire
in mountain big sagebrush-bitterbrush [Purshia tridentata (Pursh.) DC.] stands
increased several key sage grouse forbs and did not adversely affect the
abundance of key invertebrates used by sage grouse chicks. Winter (1984) found
a greater abundance of insects in burned big sagebrush stands. In contrast, fire in
mountain big sagebrush stands in Idaho had a negative impact on sage grouse
nesting and brood-rearing habitats because of the long period of time necessary
for a substantial sagebrush component to return (Nelle et al. 2000). Fischer et al.
(1996) found that fire in Wyoming big sagebrush stands did not increase key
forbs and decreased beetle abundance. Prescribed fire in a Wyoming big
sagebrush stand in Montana resulted in less herbaceous growth than other forms
of sagebrush control, which included spraying and plowing, but no differences
were observed among the 3 treatments after 30 years (Watts and Wambolt 1996)
5
Several studies have addressed the relationship between fire and sage
grouse habitat use with differing conclusions. Gates (1983) reported a greater use
of burned areas than unburned areas by sage grouse, whereas Benson et al.
(1991), Sime (1991) and Fischer et al. (1996) did not. Prescribed fire did not
influence seasonal movement patterns of female sage grouse in southeastern
Idaho (Fischer et al. 1997), but Connelly et al. (2000a) observed that fire
negatively affected male sage grouse lek attendance. Benson et al. (1991)
observed that sage grouse use of burned areas was proximate to unburned stands
of sagebrush, and recommended that prescribed fire be designed to burn in a
mosaic and be conducted on small areas. Openings in the sagebrush canopy may
increase forbs and improve brood habitat (Sime 1991), but could be a detriment to
winter and nesting habitat (Gates 1983, Nelle et al. 2000).
Fire has become an increasingly popular tool to manage sage grouse
habitats with a degraded herbaceous component to reduce shrub cover and
promote herbaceous growth. However, information that relates fire histories to
proportional use of habitats by sage grouse during the breeding season is
unavailable. Although some researchers have investigated the short-term effects
of fire on sage grouse habitat use, none have used long-term breeding season data
in conjunction with detailed long-term fire histories to determine temporal or
spatial effects of fire on sage grouse habitat use and selection. Based on
preliminary observations at HMNAR, I hypothesized that female sage grouse
used burned areas in greater proportion than their availability (i.e., selected)
6
during the reproductive period. The goal of my study was to provide a better
understanding of the long- and short-term influence of fire on female sage grouse
habitat use and selection by nesting, brood-rearing, and broodless females. My
objectives were to: 1) measure proportional use of burned areas by female sage
grouse as a function of burned area availability and, 2) determine potential
factors, such as habitat components and burned area characteristics, which may
affect habitat use and selection.
7
METHODS AND MATERIALS
STUDY AREA
Hart Mountain National Antelope Refuge (HMNAR) consists of
approximately 114,375 ha of sagebrush-steppe habitat 70 km northeast of
Lakeview, Lake County, Oregon (Fig. 1). Elevation ranged from 1500 in to 2450
in. The topography was characterized by flat sagebrush plains, interrupted by
rolling hills, ridges, and draws (Gregg et al. 1994). Since 1940, mean annual
precipitation was 29 cm, annual temperature averaged 6° C, and temperature
ranged from -22° C in winter to 36° C in summer (Gregg 1992).
HMNAR cover types were defined by Soil Conservation criteria and cover
type boundaries were delineated by interpretation of color-infrared photographs
(Gregg 1992). I subdivided cover types on the refuge into 5 types: low sagebrush,
mountain big sagebrush, Wyoming big sagebrush, burned areas, and "other"
cover types (Fig. 2). "Other" included quaking aspen (Populus tremuloides
Michx.), mountain mahogany (Cercocarpus ledifolius Nutt.), western juniper,
basin big sagebrush (A. t. Nutt. var. tridentata Nutt.), silver sagebrush (A. cana
Pursh.), and meadows (e.g., Carex L. spp., Juncus L. spp). Low sagebrush
covered approximately 38% of the refuge and was most common on ridges and in
areas with rocky soils. Graminoid species frequently associated with low
sagebrush stands were bluegrass (Poa L. spp.), bluebunch wheatgrass
[Pseudoroegneria spicata
S
Area of Detail
N
0
5
10
15
Kilometers
Figure 1. Location of Hart Mountain National Antelope Refuge, Lake County,
Oregon.
N
Wyoming Big sagebrush
Low Sagebrush
Mountain Big sagebrush
Other Cover Types
Bunted Areas
0
5
10
15 Kilometers
Figure 2. Cover type classifications at Hart Mountain National Antelope Refuge,
Lake County, Oregon.
10
(Pursh.) A. Love], Idaho fescue (Festuca idahoensis Elmer), and squirreltail
[Elymus elymoides (Raf.) Swezey]. Wyoming big sagebrush covered
approximately 33% of the refuge and was most common in xeric areas with less
productive soils. Commonly associated graminoid species in Wyoming big
sagebrush stands were bluegrass, squirreltail, and cheatgrass (Bromus tectorum
L.). Mountain big sagebrush covered approximately 13% of the refuge and was
most common at higher elevations in mesic areas with deeper and more
productive soils. Mountain big sagebrush areas with a significant component of
bitterbrush and snowberry (Symphoricarpos Duham. spp.) were common in high-
elevation areas. Graminoid species frequently associated with mountain big
sagebrush stands were Idaho fescue, rough fescue (F. campestris Rydb.), and
needlegrass (Achnatherum Piper spp. and Stipa L. spp.). Other cover types
covered approximately 16% of the refuge.
Livestock grazing was eliminated from HMNAR in December 1990.
Before 1991, grazing averaged approximately 12,000 animal unit months
(AVMs), allocated from mid-April to mid-December in a rest rotation, deferred
grazing system (Gregg 1992). Livestock grazing was the primary management
tool with some prescribed fire and herbicide use during this time.
When livestock were removed in 1990, prescribed fire became the
principal land management practice at the refuge (USDI 1994). I defined areas as
burned if they had visible signs of fire or a known history of being burned. Since
1947, 70 fires burned approximately 14% of the refuge. Twenty-nine percent of
11
mountain big sagebrush, 14% of low sagebrush, 12% of other cover types, and
5% of Wyoming big sagebrush communities at HMNAR are known to have
burned since 1947 (Fig. 2, Appendix A). Prescribed fire and escaped prescribed
fires composed 73% of total fire events (Appendix B). Seventy-one percent of
fires occurred from 1991-2000 and of these, 78% were prescribed fires.
TRAPPING AND MONITORING
Female sage grouse were trapped between 15 March and 15 April
annually from 1989 to 2000, except 1994. Habitat use data for this study were
compiled from research conducted at HMNAR by M. Gregg 1989-1991, A.
Delong 1992, M. Drut 1993, K. Coggins 1995-1996, N. Swanson 1997, and M.
Byrne 1998-2000. Grouse were captured with spotlighting techniques (Giesen et
al. 1982, Wakkinen et al. 1992). Sex and age of captured birds were determined
from wing molt and plumage characteristics (Crunden 1963, Beck et al. 1975,
Ottomeier and Crawford 1996). Females were fitted with numbered aluminum
leg bands and 20-g necklace-mounted radiotransmitters with a battery life of
approximately 350 days [Advanced Telemetry Systems (ATS), Isanti, MN]. Each
radio-marked female was monitored for 1 breeding season only to maintain
independence of samples (e.g., nest sites, brooding areas) among years.
12
Grouse were visually located 2-4 times weekly from the ground with a
hand-held Yagi antenna and a portable ATS receiver from 1 April through 31
July. Approximately equal effort was expended to gather location data for all
radio-marked females and visual locations of the same individuals were not
gathered on consecutive days. Location and cover-type assessment data were
gathered in a manner that minimized disturbance to radio-marked grouse.
Emphasis was placed on avoiding flushing radio-marked individuals or
influencing their movements. Visual locations during the breeding-season were
estimated with a Global Positioning System (GPS) unit or by visual reference to
terrain features on a 1:24,000 topographic map. Visual location data were entered
in a GIS database. When monitoring indicated a female had initiated a nest, the
nest was visually located, marked on a map, and monitored remotely. A nest was
classified as successful if > 1 egg hatched, as determined by detachment of the
eggshell membrane (Gregg et al. 1994).
Females with broods were monitored to determine habitat use and brood
success from hatching date through July. Broods were considered successful if >
I chick was recruited into the population by 1 August. Females with unsuccessful
nests were monitored to determine habitat use.
13
HABITAT SAMPLING
Habitat characteristics at nest and brood locations were sampled with 2
perpendicular transects 10-m in length centered at the nest, brood, or randomly
selected site. Shrub canopy cover was measured with the line-intercept method
with a gap criterion of 10cm (Canfield 1941). I classified height of shrubs 3
categories: short (< 40 cm), medium (40 - 80 cm), and tall ( 80 cm). Species
composition and forb and grass cover were measured in 5 plots (2-x 5-dm) placed
equidistantly along each transect (Daubenmire 1959). Tallest droop height of
graminoids, excluding flower stalks, was measured and classified into 2 classes:
short (< 20 cm) and tall (> 20 cm). Plants were identified to species according to
available vegetative and phenological characteristics; otherwise, vegetation was
identified to genus. All plant nomenclature follows Natural Resource
Conservation Service authority (USDA 2002).
GIS DATABASE
I used Erdas Imagine 8.4 (Erdas, Inc.), ArcView 3.2, and ArcInfo 8
(Environmental Systems Research Institute, Inc.) to construct a GIS database that
included fire histories (1947 - 2000), cover types, and locations of radio-marked
female sage grouse (1989 - 2000). Fire history layers were created with on-screen
14
digitizing from aerial photography and fire-history maps. Polygons developed for
old burns in which the shrub component had returned were typically more
difficult to map accurately and had correspondingly more error potential than fire
polygons created from aerial photography. Ground estimation was used to
delineate fire patterns and boundaries of older fires. Based on comparison of fire
polygons generated with ground estimation with photographic records available
for older burns, accuracy of plotted boundaries of older fires ranged from 0.5 m to
100 in. In burned areas where the shrub component had not returned, fire
boundaries generated from orthorectified aerial photos were delineated within a
0.5 - 10-m error.
Locations that were not gathered with GPS units and differentially
corrected also had higher error rates because of the reduced accuracy inherent in
less sophisticated GPS systems or location coordinates obtained from UTM grids
placed on 7.5-minute topographic quads. A buffer analysis of all locations
included in the final analysis was used to address the potential classification error
of sage grouse locations as burned or unburned. Error buffers were created for all
fire polygons and grouse locations. The width/radius of each buffer was the
maximum possible error, which was determined to be 100m for fire polygon
boundaries and grouse locations. Grouse locations with buffers that overlapped
polygon buffers were defined as potential misclassifications of locations in burned
or unburned habitats. Based on this worst-case analysis, the mean potential for
misclassification of burned vs. unburned locations was 9% (Table 1).
15
Table 1. Potential for misclassification of locations in burned and unburned
habitats: radio-marked female sage grouse at Hart Mountain National Antelope
Refuge, Lake County, Oregon, 1989-2000.
Year
Nesting
% Potential Misclassification
Brood-rearing
Broodless
Mean
1989
1990
1991
0
2
3
10
21
19
2
17
17
-
9
10
1992
0
2
3
1993
15
1995
4
0
1996
1997
1998
1999
2000
Mean
13
20
7
0
7
7
0
-
3
0
0
11
6
0
20
19
13
1
11
8
10
9
11
8
9
3
17
-
3
1
Prescribed fires and wildfires in sagebrush typically burn more than one
cover type. Therefore, I generated 50 random points within each burned area,
determined the cover type classification of each point, and used the cover type of
the majority (i.e., > 50%) of random points in the polygon as the classification of
the burn. The same method was used to determine mean elevation of burned
areas.
GIS layers of sage grouse locations during the breeding were generated
from visual locations of radio-marked females. Breeding-season locations were
categorized into 3 classes: nesting, brood-rearing, and broodless females. Use and
availability layers were generated for all location categories.
16
DATA ANALYSIS
Because of small sample size for individual birds, locations were pooled
across individuals for each year-specific category of nesting, brooding, and
broodless female locations (e.g., 1989 nests, 1989 broods, 1989 broodless, 1990
nests, 1990 broods, 1990 broodless, etc.) to compare habitat use with habitat
availability. Use was defined as observed presence in a specific cover type. I
analyzed habitat use for 203 nest locations from 203 individuals, 503 brood
locations from 58 individuals, and 694 broodless female locations from 158
individuals (Table 2).
17
Table 2. Number of nest, brood, and broodless locations of radio-marked female
sage grouse at Hart Mountain National Antelope Refuge, Lake County, Oregon,
1989-2000.
Nest
Brood
Broodless
Loc.
Year
Ind.
Loc.
Ind.
Loc.
Ind.
1989
1990
1991
1992
22
35
22
35
5
52
15
37
0
24
37
15
6
0
13
13
4
21
112
107
18
51
17
63
1993
13
13
1995
1996
27
27
6
6
17
17
5
1997
1998
1999
2000
16
16
6
46
36
78
32
10
10
3
14
17
17
10
117
9
99
18
18
7
70
17
173
Total
203
203
58
503
158
694
-
-
11
21
16
9
24
44
-
-
I used 2 methods to estimate the amount of each cover type that was
available to sage grouse during each year-specific portion of the breeding season.
In cases where the combined sample from all radio-marked grouse was >30, I
used a 95% fixed kernel estimator, with least square cross validation (LSCV). If
the combined sample of locations from all grouse was <30, I used a 100%
Minimum Convex Polygon utilization estimator (Mohr 1947, Seaman and Powell
1996). I defined cover types that were available to sage grouse as the area within
the utilization polygon boundary. Utilization distributions were generated with
the Animal Movement extension in ArcView 3.2 (Hooge et al. 1999).
1 used Chi-square goodness-of-fit tests with Bailey confidence intervals to
compare observed and expected proportions of sage grouse locations in each
18
cover type (Neu et al. 1974, Manly et al. 1993, Cherry 1996). Although other
methods could have been used (e.g., Johnson 1980, Aebischer et al. 1993), I chose
the Neu et al. (1974) method because McLean et al. (1998: 793) found that it
better identified "habitat selection patterns consistent with known requirements"
compared with other methods. I used P < 0.05 as the cutoff for determination of
significance in all statistical tests. Use of burned and unburned habitats was
defined as: 1) Selected - cover types used in greater proportion than their
availability; 2) Cover types used in proportion to their availability; 3) Cover types
used less than their availability; and 4) Avoided - no measured use.
All assumptions outlined by Alldredge et al. (1998) for the use of Chi-
square tests in resource selection studies were addressed. I used the Schoener
(1981) estimator, as described by Swihart and Slade (1985), to test for auto-
correlation of locations. Five locations that did not meet independence criteria
were removed from the data set. Each year-specific category was analyzed
separately to control for annual variation and changes in burned area availability
(Schooley 1994). Birds with a large deviation in number of locations from the
mean number within each category were excluded from the analysis to avoid the
possible anomalous influence of those individuals in the overall analysis
(Alldredge and Ratti 1992). Differences in breeding-season movement patterns of
radio-marked individuals at HMNAR were investigated by comparing the sizes of
individual 100% MCP utilization distributions. Selection analysis results for each
category were pooled across years to control for the influence of 4th order habitat
19
changes that may have been influenced by climatic variation and could possibly
affect year-to year habitat use (Johnson 1980, Schooley 1994). All types of fires
(e.g., prescribed, escaped prescribed, and wildfires) were pooled and defined as I
cover type to reduce potential Type I errors associated with an increased number
of habitat categories included in the analysis (Alldredge and Ratti 1986).
I used logistic regression models to evaluate use patterns of burned areas
by nesting, brood-rearing, and broodless females. Explanatory variables included
in the model were: cover type burned, age and size of burn, annual precipitation,
year, and elevation. In the logistic model, cover type use was categorized as: used
(selected, used in proportion, or used less than available) or not used (avoided or
no measurable use).
AMANOVA (Multivariate Analysis of Variance) was used to compare
habitat components (e.g., shrub, forb, and grass cover) of utilized areas by nesting
and brood-rearing females in burned and unburned habitats. If significant
differences were found (P < 0.05), Tukey-Kramer multiple comparisons were
used to determine what habitat components contributed to the differences
(Ramsey and Schafer 1997).
20
RESULTS
NESTING
Unburned mountain big sagebrush was consistently selected in all years
(x2= 21.53, 4 df, P < 0.001). A high-elevation late-successional (39-42 years old)
mountain big sagebrush burned area was selected in 1991 and 1996. However, in
1999, there was no difference in shrub, forb, or grass cover in this burn compared
with unburned mountain big sagebrush habitats (Table 3). With the exception of
mountain big sagebrush, other unburned cover types were used proportionally or
used less than available (Appendices D, E, F, G, H).
Table 3. Sage grouse habitat characteristics (% cover) in a 1954 mountain big
sagebrush burn (Degarmo Canyon Wildfire) and unburned mountain big
sagebrush at Hart Mountain National Antelope Refuge, Lake County, Oregon,
1999.
Resource
Forb
Short Grass
Tall Grass
Low shrub
Medium shrub
Tall shrub
Burned (1954)
Mean
SE
21.6
2.6
31.6
2.1
Unburned (1999)
SE
Mean
22.9
23.6
3.1
3.6
0.6
1.6
0.4
13.0
35.6
3.7
5.7
15.6
28.7
4.8
5.5
0.0
0.0
4.0
3.2
2.1
21
Burned areas composed 15% of cover types available to nesting females
(Appendix Q. Burned areas were generally avoided for nesting, with only 11%
of burned areas used (Table 4, Table 5). Use tended to increase with increasing
age of the bum (Table 4, Fig. 3).
Table 4. Use of burned areas by radio-marked nesting female sage grouse during
the breeding season at Hart Mountain National Antelope Refuge, Lake County,
Oregon, 1989-2000. Mean age of burns in each use category is also indicated.
Use Response
%
Mean Age (yr)
Select
1.0
39.5
Proportional
Less than available
9.0
25.5
1.0
25.0
8.9
Avoid
89.0
22
Table 5. Use of burned cover types by nesting female sage grouse at Hart
Mountain National Antelope Refuge, Lake County, Oregon, 1989-2000. Mean
age and number of bums in each category is also indicated.
Burned Cover Type
Low sagebrush
Mountain big sagebrush
Response
Select
% Use Mean Age
4
19
Proportional
Less than available
2
75
Avoid
39.5
27.0
25.0
14.6
N
% Use
2
10
-
1
39
4
Mean Age
N
-
-
22.0
1
-
-
-
96
7.7
27
Table 5. (Continued).
Response
Burned Cover Type
Other
Wyoming big sagebrush
% Use Mean Age
% Use Mean Age N
Select
-
-
Proportional
Less than available
Avoid
6
-
13.0
94
6.4
-
1
15
N
-
-
-
100
3.2
43
23
50 -r
100
0
40t
80
N
60
20
40
CI Mean Age
A Use Response
10-f0
A {ir- -I---i- 0
S
P
L
A
Use Response
Figure 3. Mean age of burned areas available to radio-marked nesting female
sage grouse as a function of use response at Hart Mountain National Antelope
Refuge, Lake County, Oregon, 1989-2000. S - Selected, P - Proportional Use, L
- Less than Available, A- Avoided.
Lack of data-point convergence in burned areas used by nesting females
precluded logistic modeling, because 90% of burned areas used by nesting
females were in mountain big sagebrush (Table 3). Mountain big sagebrush burns
were used more than other burned cover types (X2 = 12.09, 3 df, P = 0.008), and
burned areas > 20 years old were used more than burned areas < 20 years old (z
= 11.63, 1 df, P < 0.001).
Ally nests in burns < 20 years old were unsuccessful. Nesting success in
>20 year burns (29%, n = 6/2 1) was similar to nesting success in unburned areas
(28%, n = 49/177). Habitat components for nests in burns > 20 years old and
nests in unburned areas were similar (Table 6).
24
Table 6. Habitat components of sage grouse nest sites in recently burned areas (<
20 years-old), old burns (> 20 years-old), and unburned areas at Hart Mountain
National Antelope Refuge, Lake County, Oregon, 1989-2000.
Resource
< 20-year-old
burns
Mean
SE
> 20-year-old
burns
Mean
SE
Unburned
Mean
SE
1.2
Forb
Short Grass
14.3
19.5
6.2
6.6
10.7
10.3
2.8
3.3
15.8
10.4
Tall Grass
3.1
15.2
5.4
13.8
Short shrub
5.1
22.3
0.9
1.5
11.5
17.8
3.8
14.6
1.4
Medium shrub
Tall shrub
20.6
0.0
8.8
0.0
32.8
0.7
6.3
0.7
32.7
1.9
1.2
5.3
BROOD-REARING
Estimated sizes of areas utilized by individual brood-rearing females
(100% MCP) were highly variable (Mean = 1347 ha, SE = 435, 95% Cl = 453 -
2243). Unburned low sagebrush and mountain big sagebrush cover types were
consistently selected or used in proportion to their availability by brooding
females. Unburned Wyoming big sagebrush and other unburned habitats were
used less than available or avoided (,, = 9.52, 4 df, P = 0.048). Other unburned
cover types were used in proportion to their availability or used less than available
(Appendices I, J, K, L, M).
Burned areas composed 14% of habitats available to brooding females
(Appendix Q. Burned areas were generally avoided by brooding females, with
only 11% of burned areas used (Table 7, Table 8). Exceptions included a 44 year-
25
old high-elevation late-successional mountain big sagebrush burned area that was
selected in 1998. A 7-year-old mountain big sagebrush burn, a 30-year-old highelevation mid-successional mountain big sagebrush burn, and a 36-year-old highelevation late-successional mountain big sagebrush burn were used in proportion
to their availability in 1990 and 1992. Use tended to increase with increasing age
of the burn (Table 7, Fig. 4).
Table 7. Use of burned areas by radio-marked brooding female sage grouse
during the breeding season at Hart Mountain National Antelope Refuge, Lake
County, Oregon, 1989-2000. Mean age of burns in each use category is also
indicated.
Response
Select
Proportional
Less than available
Avoid
%
2.0
8.0
Mean Age (yr)
1.0
89.0
17.7
9.8
31.8
22.6
26
Table 8. Use of burned cover types by brooding female sage grouse at Hart
Mountain National Antelope Refuge, Lake County, Oregon, 1989-2000. Mean
age and number of burns in each category is also indicated.
Burned Cover Type
Low sagebrush
Mountain big sagebrush
Response
Select
% Use Mean Age
N
4
37.3
3
Proportional
Less than available
11
25.0
10
2
Avoid
83
17.7
14.4
2
74
% Use
Mean Age
N
8
-
-
22.0
-
2
-
92
6.6
24
% Use
Other
Mean Age
N
Table 8. (Continued).
Wyoming big sagebrush
% Use Mean Age N
Response
2
15.0
-
2
-
10.0
-
-
12
96
3.3
47
-
-
-
Select
14
Proportional
Less than available
Avoid
86
12.5
-
9.4
2
1
1
27
40-r
100
80
.
60
%
V
40
Mean Age
A Use Response
20
A
0
S
P
L
A
Use Response
Figure 4. Mean age of burned areas available to radio-marked brooding female
sage grouse as a function of use response at Hart Mountain National Antelope
Refuge, Lake County, Oregon, 1989-2000. S - Selected, P - Proportional Use, L
- Less than Available, A- Avoided.
The logistic model that best fit the data from brooding females suggested
that: 1) burned areas > 20 years-old were used more than burned areas < 20 years-
old (,j = 9.39, 1 df, P = 0.002); 2) burns in mountain big sagebrush were used
more than burns in other cover types (,
= 11.52, 3 df, P = 0.009); and 3) there
was a year-effect on use of burns in 1990 and 1996 where brooding females
tended to exhibit more use of burned areas(, = 20.96, 9 df, P = 0.017).
However, I found no differences in any characteristics of the annual samples, such
28
as sample size, age distribution, or capture locations that helped to explain the
year-effect. Plant phenology information was unavailable, but could be an
influence. No other variables (i.e., size of burn, precipitation, or elevation)
contributed to model performance.
Brood sites in > 20 year-old burned areas had greater cover of short
shrubs than brood sites in burned areas that were < 20 years old (t44 = 3.369, P <
0.001) (Table 9). Brood sites in > 20 year-old burned areas had more cover of
medium shrubs than brood sites that were in burned areas < 20 years old (t44 =
2.96, P = 0.003). Forb cover was similar in < 20 year-old burned areas and > 20
year burned areas. There were no differences in brood-site habitat variables for >
20 year-old and brood sites in unburned areas.
Table 9. Habitat components of sage grouse brood sites in recently burned areas
(< 20 years-old), old burned areas (> 20 years-old), and unburned areas at Hart
Mountain National Antelope Refuge, Lake County, Oregon, 1989-2000.
< 20 year-old
> 20 year-old
burns
burns
Unburned
Resource
Mean
SE
Mean
SE
Mean
SE
Forb
Short Grass
19.05
2.9
3.8
1.6
0.9
17.3a
2.7
2.9
1.8
2.5
17.05
0.6
21.5a
09
16.2b
0.6
9.0b
0.7
34.2a
Tall Grass
8.3a
Short shrub
1.95
20.05
16.4b
9.9b
Medium shrub
0. l a
0.1
0a
0
0.9a
0.2
Tall shrub
19.05
2.9
17.3a
2.7
17.05
0.6
a
Within-row means followed by a different letter are significantly different at (P
< 0.05).
29
BROODLESS FEMALES
Estimated sizes of areas utilized by broodless females (100% MCP) were
highly variable (Mean = 2096 ha, SE = 354, 95% Cl = 1367 - 2826). Unburned
low sagebrush was consistently selected in all years (x2 = 11.33, 4 df, P = 0.023).
Compared to brooding and nesting females, broodless females exhibited more
plasticity in terms of proportional use of unburned habitats (Appendices N, 0, P,
Q, R).
Burned areas composed 21% of habitats available to broodless females
(Appendix Q. Burned areas were selected during 1989, 1990, and 1992;
otherwise available burned areas were avoided (77%), with only 23% of burned
areas used (Table 10, Table 11). A 35-38 year-old high-elevation latesuccessional mountain big sagebrush burn was selected during 1989, 1990, and
1992, a 27 year-old mountain big sagebrush burn was selected during 1989, and
an 11-14 year-old low sagebrush burn was selected during 1989 and 1992.
30
Table 10. Use ofburned areas by radio-marked broodless female sage grouse
during the breeding season at Hart Mountain National Antelope Refuge, Lake
County, Oregon, 1989-2000. Mean age of burns in each use category is also
indicated.
%
Mean Age (yr)
4.0
16.0
3.0
26.5
Proportional
Less than available
Avoid
77.0
9.3
Response
Select
18.5
17.8
Table 11. Use of burned cover types by broodless female sage grouse at Hart
Mountain National Antelope Refuge, Lake County, Oregon, 1989-2000. Mean
age and number of burns in each category is also indicated.
Response
Burned Cover Type
Other
Wyoming big sagebrush
% Use Mean Age
% Use Mean Age N
Select
Proportional
Less than available
Avoid
5
31.5
24
6
65
24.6
4
18
17.8
15.9
4
48
12
12
-
76
22.0
16.8
5.9
N
2
2
13
Table 11. (Continued).
Response
Burned Cover Type
Other
Wyoming big sagebrush
% Use Mean Age
% Use Mean Age_ N
N
Select
Proportional
Less than available
Avoid
33
11.0
2
2
6.0
1
66
4.0
4
98
3.6
48
31
Use increased with increasing age of burn (Table 10, Fig. 5). No variables
(i.e., cover type burned, age of burn, size of burn, precipitation, year, or elevation)
contributed to logistic-regression model performance.
30,-
90
80
70
.
60
44
50
40
30
20
-
Mean Age
- A Use Response
10
S
P
L
A
Use Response
Figure 5. Mean age of burned areas available to radio-marked broodless female
sage grouse as a function of use response at Hart Mountain National Antelope
Refuge, Lake County, Oregon, 1989-2000. S - Selected, P - Proportional Use, L
- Less than Available, A- Avoided.
32
DISCUSSION
My analysis indicated that unburned areas were generally selected and
burned areas were generally avoided by female sage grouse at HMNAR during
the breeding season. Although variables such as size of burn, annual
precipitation, and elevation did not significantly contribute to the logisticregression model, age of burn and the cover type burned affected sage grouse use
of burned areas. Age of burn, and the resultant return of the shrub (i.e.,
sagebrush) component, was most positively associated with use of burned areas
by nesting and brood-rearing female sage grouse. The cover type burned also had
a strong influence on selection of nest and brood sites. When burned habitats
were used, they were typically > 20 year-old burns that occurred in mountain big
sagebrush. Use of these particular burned areas may be related to the higher
biotic potential (in terms of soil productivity/structure, floral diversity, and
precipitation) typically associated with mountain big sagebrush habitats and,
subsequently, more rapid recovery of these cover types after fire (Miller and
Eddleman 2000). However, there was a much higher proportion of mountain big
sagebrush burns at HMNAR than bums in any other cover type. Consequently,
analysis results may have been biased towards use of mountain big sagebrush
burns because of the limited number of burns in the other 3 cover types available
to nesting, brood-rearing and broodless females.
33
Dunn and Braun (1986) observed that sage grouse avoided areas without
sagebrush cover as they migrated towards wintering grounds. My study
demonstrated a similar trend for nesting, brood-rearing, and broodless females.
Sime (1991) observed sage grouse use of a 12-year-old burned area in spring but
saw no overall difference in use of burned and unburned areas. I observed little or
no use of burned areas < 20 years old by breeding females in cover types other
than mountain big sagebrush.
Several studies have indicated a post-fire increase in cover, abundance,
and nutritive content of forbs (Harniss and Murray 1973, Bailey and Anderson
1978, Cook et al. 1994, Pyle and Crawford 1996, McDowell 2000), which
theoretically should benefit sage grouse. However, the loss of the shrub
component may have countered any benefits from increases in forb cover,
abundance, or nutritive content, at least during the nesting, brood-rearing, and
broodless stages. Due to the significant amount of time necessary for the
sagebrush component to return in and environments, the role that fire may play in
long-term (> 100 years) rehabilitation of degraded sagebrush ecosystems remains
poorly understood. Foundations for evaluating these possible effects, such as sitespecific long-term monitoring of burned areas, should be implemented to assist
future researchers.
Mapping error or location error is always a concern in studies of habitat
use. In my analysis, I estimated that the maximum misclassification rate of
grouse locations due to mapping error and location error was 9%. This worst-case
34
scenario was based on an analysis in which I assumed that all grouse locations
and all burned area polygon boundaries were off by the maximum amount that I
observed. In reality, mapping and location errors were distributed somewhat
normally, which would mean that the actual misclassification rate was
considerably less than 9%.
If I used the study area boundary as the frame of reference for computing
habitat availability (as opposed to the kernel and MCP utilization areas), results of
the selection analyses did not change for burned vs. unburned areas or for any
cover type, except that low sagebrush went from being selected to being used in
proportion to its availability. This result was predictable because areas outside
the utilization distribution boundaries were dominated by low sagebrush.
The influence of autocorrelated locations in habitat selection studies is
often debated (Otis and White 1999) and has led some to adapt rigid sampling
designs in which observations are spaced at wide temporal intervals (Carey et al.
1989). In this study, emphasis was placed on reduction of autocorrelation of
locations gathered from radio-marked individuals, and the Schoener (1981)
method was used to test for autocorrelation. However, Otis and White (1999)
suggested that this approach may result in the exclusion of information valuable
to further understand animal-habitat spatial interactions, and that autocorrelation
of locations is irrelevant if the locations are defined in a specific temporal context.
In addition, Legendre (1993) suggested that autocorrelated locations may provide
useful information about habitat interactions and Hansteen et al. (1997) suggested
35
that the Schoener (1981) ratio may be a more useful tool to describe spatial use
instead of a technique used to test solely for statistical independence of locations.
In my analysis, small sample sizes of relocations for individual grouse
precluded analyses of habitat selection for individuals. This was unfortunate
because comparison of individual home ranges suggested substantial variability in
the amount of area utilized by individuals, which may be an indicator of
individual variability if a relationship exists between the amount of area used by
an individual and the use of cover types within that area by an individual. If I
were to repeat this study I would place less emphasis on statistical independence
of locations and more emphasis on collecting large numbers of relocations from
individual birds so that I could better evaluate individual variation in habitat use,
instead of pooling data from many individuals. The latter approach undoubtedly
concealed individual variability in habitat use (Schooley 1994).
In regard to prescribed fire, or any other habitat management technique,
managers should be cautious in the use of habitat "selection" derived from
resource selection studies as a mechanism to evaluate specific management
techniques. While selected habitats are obviously important, they are by no
means the only necessary sage grouse habitats. Sage grouse habitats and habitat
requirements must continue to be viewed at a landscape level and across human-
designated boundaries. In terms of sage grouse habitat use, habitat selection may
be more importantly the result of interactions between cover types, habitat
components within those cover types, and site fidelity. Although Eng and
36
Schladweiler (1972), Berry and Eng (1985), and Connelly et al. (1988) have
observed trends of traditional habitat use and fidelity by sage grouse, the role of
site fidelity in sage grouse habitat use remains poorly understood and may be a
determinant of habitat use, regardless of habitat condition. Anecdotal information
from previously radio-marked individuals at HMNAR indicates patterns of site
fidelity, but the samples were too small for analysis. The effect of fire on habitat
use by sage grouse may be best addressed by monitoring the same individuals for
several years, while implementing fire management, and observe habitat use of a
specific area by individuals in pre- and post-treatment years. This approach may
also facilitate our understanding of the role that site and habitat fidelity plays in
habitat use.
Although future research may further elucidate use of burned habitats by
sage grouse, managers should be cautious in the use of prescribed fire treatments
in sage grouse habitats. Maintenance of accurate and long-term fire records is a
critical need for future studies and will assist managers in prescribed fire
planning. While prescribed fire has the potential to rehabilitate the herbaceous
component in sagebrush ecosystems (Klebenow 1985, Bunting et al. 1987,
Laycock 1991), site-specific characteristics are the key to understanding habitat
response (Miller and Eddleman 2000). Fire should be used cautiously in nesting
and brood-rearing areas, and substantial amounts of unburned areas should be
retained to provide spatial and temporal variability of habitats, where the
unburned areas would provide a balance of shrubs, forbs, grasses, and
37
invertebrates necessary for sage grouse as outlined by Connelly et al. (2000b).
Managers, who use prescribed fire as a management tool, should not overlook the
need to manage for habitats that provide the necessary habitat components for all
sage grouse life-history attributes (Beck 1977).
38
LITERATURE CITED
Aebischer, N.J., P.A. Robertson, and R.E. Kenward. 1993. Compositional
analysis of habitat use from animal-tracking data. Ecology 74:1313-1325.
Alldredge, J.R., and J.T. Ratti. 1986. Comparison of some statistical techniques
for analysis of resource selection. Journal of Wildlife Management
50:157-165.
Alldredge, J.R., and IT. Ratti. 1992. Further comparison of some statistical
techniques for analysis of resource selection. Journal of Wildlife
Management 56:1-9.
Alldredge, J.R, D.L Thomas, and L.L. McDonald. 1998. Survey and comparison
of methods for study of resource selection. Journal of Agricultural,
Biological, and Environmental Statistics 3: 227-253.
Bailey, A.W., and M.L. Anderson. 1978. Prescribed burning of a Festuca-Stipa
grassland. Journal of Range Management 31:446-449.
Barnett, J.K., and J.A. Crawford. 1994. Pre-laying nutrition of sage grouse hens
in Oregon. Journal of Range Management 47:114-118.
Beck, T.D. 1977. Sage grouse flock characteristics and habitat selection in
winter. Journal of Wildlife Management 41:18-26.
Beck, T.D., R.B. Gill, and C.E. Braun. 1975. Sex and age determination of sage
grouse from wing characteristics. Game Information Leaflet. 49 (revised).
Colorado Division of Wildlife.
Benson, L.A., C.E. Braun, and W.C. Leininger. 1991. Sage grouse response to
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46
APPENDICES
47
Appendix A. Fire events at Hart Mountain National Antelope Refuge, Lake
County, OR, 1947-2000.
Fire Name
Date
Dominant
Habitat Type
Fire
Type
Mean
Elevation
(m)
Fire Size
(ha)
BumedA
1790
27.9
WBS
W
CCC
1953
Rx/W
1687
1209.8
MBS
__PJ Jumper------------- Summer 1954
1861
MBS
W
2.4
Degarmo
Fall 1954
959.8
MBS
W
2189
Goat Creek
Summer 1959
MBS
W
179.5
1840
Deer Creek Basin
9-5-1962
MBS
2084
162.7
Rx
Hammersly Spring 1972
1938
2877.3
MBS
Rx
PJ Spring
1978
LS
Rx
211.8
1732
Wire Corral
1984
Rx/W
1780
41.6
LS
Flook Knoll
8-24-1985
Rx
1555
603.4
WBS
------------------------------------------------------------------------------------------------Hart Mountain
8-29-1985
4346.9
Rx/W
MBS
1854
Blue Sky
1985
Rx
1882
1.9
OTHER
Potter
8-5-1988
0.4
MBS
1939
W
South Mtn
8-6-1988
MBS
1855
0.3
W
South Mtn #1
10-5-1990
Rx
2242
178.9
MBS
----------------------------------------------------------------------------------- -----------------Hunter
10-12-1990
2257
MBS
W
2.1
Blue Sky
10-13-1990
4.5
MBS
W
2268
Rock Pile
8-18-1991
MBS
4.0
W
1816
PJ Guzzler
10-1-1991
3.3
Rx
1725
OTHER
Unkn
1991
W
2002
10.0
MB S
Potter Canyon
6-24- 1992
MBS
W
2212
0 .4
- ------------South Mtn #2
10-23-1992
MBS
Rx
2301
191.0
Bond Creek
10-27-1992
Rx
1885
162.3
OTHER
Upper Guano
11-25-1992
17.5
MBS
Rx
2094
Paiute Creek #1
10-25-1993
81.3
OTHER
Rx
1921
NE Hart
1-27-1994
MBS
Rx
1798
154.2
Paiute Creek #2
3-10-1994
44.1
OTHER
Rx
1794
CCC #1
3-30-1994
559.5
WBS
Rx
1675
Stonewall #1
3-30-1994
OTHER
Rx
1645
29.7
Stonewall #2
3-30-1994
Rx
1544
12.0
OTHER
S. Blizzard
9-13-1994
LS
Rx
1703
99.7
N . Blizzard #1
10-3-1994
LS
Rx
1691
5 .8
---------------------- --- ----------------------------------- ---------------Paiute Creek #3
10-5-1994
MBS
Rx
1946
32.9
CCC #2
10-12-1994
WBS
Rx
Lyons/Willow____
2-21-1995
161.5
OTHER---------Rx---- ------ 1714_
- - ------------ -Cat Butte/Long L_
8-30-1995
Rx
1781
128.0
LS
------ ----------------------Blue Sky #1
9--- ----------------------------------------------------------i995
MBS
Rx
1865
_22.7
---------Blue Sky #2
10-13-1995
Rx- ---------- 1962
46.2
OTHER
-------- ------ Rock
Creek
10-14-1995
WBS
Rx
1517
119.1
----------------------------------------------------------------------------------------------------------------
Big Flat
Summer 1947
Blue_ __________________11-2-1995 ___-__-___-_-WBS _--______W___-__ -__-1386
Stonewall #3
12-22-1995
OTHER
Rx
1574
-___26 --_28.0
MBS - Mountain big sagebrush, LS - Low sagebrush, WBS - Wyoming big
sagebrush, OTHER - Other cover types.
48
Appendix A. (Continued).
Fire Name
Date
Dominant
Habitat Type
Fire
Type
Mean
Elevation
(m)
Fire Size
(ha)
BurnedA
4-28-1996
Valet Springs--Rx
1770
OTHER
4.1
Rim
0 7-8-26-1996
LS
W
2053
---------9-9-1996
1766
272.2
wale
Rx
LS
105.4
Flook Meadow
9-16-1996
Rx
1564
OTHER
Valet #2
35.3
9-18-1996
1746
Rx
OTHER
Warner Pond
4-14-1997
1506
0.9
WBS
Rx
-------------------------------------------------------------------------------------------------------------------N. Blizzard
Rx
1691
90.7
8-19-1997
LS
N. Blizzard Esc
8-19-1997
1676
154.5
LS
W
9-1997
1583
402.6
OSU WBS
WBS
Rx
Big Flat
1789
624.2
10-15-1997
OTHER
Rx
0.5
Flook Piles
3-12-1998
WBS
Rx
1558
9.8
Paiute Meadow
1736
3-18-1998
Rx
OTHER
--Upper Rock
18.9__
4-22-1998
1.663
OTHER_____ -Ax----------Lyons Meadow
4-22-1998
1696
73.4
Rx
------------------------------- OTHER
------------------------Norm
0.5
7-28-1998
LS
W
1769
N Blizzard #3
8-25-1998
LS
Rx
1694
348.3
Swede #1
8-31-1998
368.7
Rx
1677
LS
Swede #2
9-17-1998
1694
110.0
LS
Rx
9-28-1998
Blue Sky
Rx
1871
1.3
OTHER
Lyons/Rockhouse
4-20-1999
Rx
1748
123.2
OTHER
- ----------------------------------------------------------------------------------------------------Corral East
5-11-1999
Rx
1799
5.6
OTHER
Springs--9-15-1999
MBS
1868
5.2
-Hot
W
Degarmo
1023.7
11-7-1999
MBS
W
2174
Corral Meadow
3-28-2000
1780
21.9
OTHER
Rx
Mid Rock
56.6
3-30-2000
Rx
1583
OTHER
----------------------------------------------------------------------------------------------------------------3-31-2000
Corral Escape
MBS
W
------------------------------Corral West
3-31-2000
MBS
Rx
1920
146.5
---- --------- ------------Post Meadow
10-18-2000
Rx
252.5
1830
OTHER
.
MBS - Mountain big sagebrush, LS - Low sagebrush, WBS - Wyoming big
sagebrush, OTHER - Other cover types.
49
Appendix B. Number and type of fire events at HMNAR, 1947-2000.
Year
Prescribed
1947
1953
1954
1959
0
0
1962
1
1972
1978
1
1984
1985
1988
1990
1991
0
2
1992
1993
3
1994
1995
1996
9
6
4
1997
1998
1999
2000
4
Total
0
0
1
Type of fire
Escaped Prescribed
Wildfire
1
0
2
1
0
0
0
0
0
2
2
2
0
1
1
1
0
0
0
2
0
1
0
1
1
3
2
3
4
6
70
8
1
4
2
2
48
19
3
1
1
1
0
0
1
1
1
1
1
2
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
Total
3
4
1
9
7
5
5
9
50
Appendix C. Percentage of burned area within utilization distribution estimates
generated for pooled individual radio-marked female sage grouse at Hart
Mountain National Antelope Refuge, Lake County, Oregon, 1989-2000.
% Burned Area in Utilization Distribution
Category
Nesting
Brooding
Broodless
Year
1989
7
16
17
1990
21
26
18
1991
9
1992
51
27
1993
6
13
1995
1996
10
15
14
8
15
28
1997
1998
10
11
21
10
14
1999
24
25
12
21
2000
38
30
Mean
15
14
21
17
19
Appendix D. Habitat selection of low sagebrush cover types by radio-marked
nesting female sage grouse with Bailey simultaneous confidence intervals at
HMNAR, 1989-2000.
Year
Lower 95% Cl
Upper 95% Cl
1989
1990
0.1609
0.2941
0.3671
0.3496
0.1287
0.2290
0.1531
0.2223
0.0767
0.2657
0.3591
0.2037
0.3348
0.4329
0.4198
0.1810
0.2715
0.2012
0.2787
0.1265
0.3232
0.4188
1991
1992
1993
1995
1996
1997
1998
1999
2000
% Available
0.310
0.298
0.466
Action
Avoid
Neutral
Avoid
0.284
Select
0.453
0.443
0.353
0.402
0.367
Avoid
Avoid
Avoid
Avoid
Avoid
0.188
Select
0.463
Avoid
51
Appendix E. Habitat selection of mountain big sagebrush cover types by radiomarked nesting female sage grouse with Bailey simultaneous confidence intervals
at HMNAR, 1989-2000.
Year
1989
1990
1991
1992
1993
1995
1996
1997
1998
1999
2000
Lower 95%
Cl
Upper 95%
Cl
% Available
Action
0.5633
0.4352
0.3019
0.2748
0.7373
0.5110
0.4976
0.2223
0.6607
0.5567
0.3591
0.6177
0.4789
0.3652
0.3414
0.7982
0.5599
0.5605
0.2787
0.7362
0.6187
0.4188
0.068
0.221
0.263
0.179
0.190
0.165
0.089
0.122
0.109
0.297
0.174
Select
Select
Select
Select
Select
Select
Select
Select
Select
Select
Select
Appendix F. Habitat selection of other cover types by radio-marked nesting
female sage grouse with Bailey simultaneous confidence intervals at HMNAR,
1989-2000.
Year
Lower 95%
CI
Upper 95%
Cl
1989
1990
1991
1992
1993
1995
0.0346
0.0217
0.0011
0.0013
0.0013
0.0925
0.0449
0.0477
0.0017
0.0010
0.0009
0.058
0.0365
0.0033
0.0038
0.0038
0.1229
0.0749
0.0795
0.0049
0.0029
0.0027
1996
1997
1998
1999
2000
% Available
0.101
0.167
0.108
0.077
0.081
0.095
0.062
0.054
0.048
0.178
0.048
Action
Avoid
Avoid
Avoid
Avoid
Avoid
Neutral
Neutral
Neutral
Avoid
Avoid
Avoid
52
Appendix G. Habitat selection of Wyoming big sagebrush cover types by radiomarked nesting female sage grouse with Bailey simultaneous confidence intervals
at HMNAR, 1989-2000.
Year
1989
1990
1991
1992
1993
1995
1996
1997
1998
1999
2000
Lower 95%
Cl
Upper 95%
0.1609
0.0217
0.0509
0.0013
0.0588
0.0593
0.0981
0.3436
0.1680
0.0010
0.0424
0.2037
0.0365
0.0848
0.0038
0.0976
0.0848
0.1389
0.4065
0.2341
0.0029
0.0707
Cl
% Available
0.447
0.115
0.068
0.000
0.213
0.231
0.420
0.341
0.377
0.097
0.045
Action
Avoid
Avoid
Neutral
n/a
Avoid
Avoid
Avoid
Neutral
Avoid
Avoid
Neutral
Appendix H. Habitat selection of burned cover types by radio-marked nesting
female sage grouse with Bailey simultaneous confidence intervals at HMNAR,
1989-2000.
Year
Lower 95%
CI
Upper 95%
Cl
1989
1990
0.0008
0.1552
0.1738
0.2748
0.0013
0.0272
0.0981
0.0477
0.0017
0.0981
0.1445
0.0022
0.1883
0.2276
0.3414
0.0038
0.0456
0.1389
0.0795
0.0049
0.1389
0.1902
1991
1992
1993
1995
1996
1997
1998
1999
2000
% Available
0.075
0.172
Action
Avoid
Neutral
0.095
Select
0.460
0.062
0.099
Avoid
Avoid
Avoid
0.080
Select
0.101
0.098
0.239
0.269
Avoid
Avoid
Avoid
Avoid
53
Appendix I. Habitat selection of low sagebrush cover types by radio-marked
brooding female sage grouse with Bailey simultaneous confidence intervals at
HMNAR, 1989-2000.
Year
Lower 95%
CI
Upper 95% CI
% Available
Action
1989
1990
0.5590
0.5486
0.5945
0.5909
0.153
0.154
Select
Select
1991
-
-
-
-
1992
1993
0.1234
0.0765
0.1632
0.0981
0.125
0.190
Neutral
Avoid
1995
0.5338
0.5767
0.406
Select
1996
1997
1998
0.1327
0.1400
0.0012
0.1534
0.1734
0.0035
0.165
0.157
0.333
Avoid
Neutral
Avoid
1999
0.2545
0.2756
0.237
Select
2000
0.1324
0.1541
0.141
Neutral
Appendix J. Habitat selection of mountain big sagebrush cover types by radiomarked brooding female sage grouse with Bailey simultaneous confidence
intervals at HMNAR, 1989-2000.
Year
1989
1990
Lower 95%
Cl
0.2912
0.1737
Upper 95% Cl % Available
0.3243
0.316
0.2072
0,375
1991
-
-
-
-
1992
1993
0.4478
0.5243
0.5044
0.5623
0.296
0.187
Select
Select
1995
0.1776
0.2119
0.208
Neutral
1996
1997
0.3366
0.2914
0.3647
0.3339
0.177
0.146
Select
Select
1998
0.0545
0.0907
0.085
Neutral
1999
0.4750
0.5274
0.4989
0.5582
0.086
0.292
Select
Select
2000
Action
Neutral
Avoid
54
Appendix K. Habitat selection of other cover types by radio-marked brooding
female sage grouse with Bailey simultaneous confidence intervals at HMNAR,
1989-2000.
Year
Lower 95%
Cl
1989
0.0147
0.0248
0.245
1990
0.0004
0.0013
0.083
Action
Avoid
Avoid
1991
-
-
-
-
1992
1993
0.0793
0.0004
0.1128
0.0011
0.108
0.163
Neutral
Avoid
1995
0.2046
0.2405
0.119
Select
1996
1997
0.0457
0.2001
0.0588
0.2381
0.118
0.212
Avoid
Neutral
1998
0.1193
0.1682
0.068
Select
1999
0.1455
0.0002
0.1628
0.0007
0.339
0.093
Avoid
Avoid
2000
Upper 95% Cl % Available
Appendix L. Habitat selection of Wyoming big sagebrush cover types by radiomarked brooding female sage grouse with Bailey simultaneous confidence
intervals at HMNAR, 1989-2000.
Year
1989
1990
Lower 95%
CI
0.0319
0.0004
Upper 95% Cl
0.0458
0.0013
% Available
0.094
0.132
Action
Avoid
Avoid
1991
-
-
-
-
1992
0.0008
0.0024
0.010
1993
1995
1996
1997
1998
0.3297
0.0005
0.3236
0.2605
0.4649
0.0001
0.0108
0.3661
0.0014
0.3515
0.3018
0.5344
0.0004
0.0183
0.331
0.123
0.390
0.351
0.478
0.221
0.017
Avoid
Neutral
Avoid
Avoid
Avoid
Neutral
Avoid
Neutral
1999
2000
55
Appendix M. Habitat selection of burned cover types by radio-marked brooding
female sage grouse with Bailey simultaneous confidence intervals at HMNAR,
1989-2000.
1989
1990
Lower 95%
Cl
0.0495
0.2218
Upper 95% CI
0.0663
0.2583
% Available
0.161
0.256
Action
Avoid
Neutral
1991
-
-
-
-
1992
1993
0.2604
0.0165
0.3116
0.0278
0.266
0.128
1995
0.0211
0.0355
0.146
1996
1997
0.1077
0.0239
0.1267
0.0401
0.150
0.105
Neutral
Avoid
Avoid
Avoid
Avoid
1998
0.2549
0.3177
0.136
Selects
1999
2000
0.0872
0.1011
0.118
0.2857
0.3140
0.474
Avoid
Avoid
Year
Appendix N. Habitat selection of low sagebrush cover types by radio-marked
broodless female sage grouse with Bailey simultaneous confidence intervals at
HMNAR, 1989-2000.
Year
Lower 95%
CI
Upper 95% Cl % Available
0.3576
0.4007
0.5900
0.5074
0.3813
0.4250
0.6254
0.5399
0.391
0.306
0,424
0.277
-
-
-
-
1997
0.6879
0.5569
0.3000
0.7392
0.6091
0.3364
0.291
0.404
0.297
Select
Select
Select
1998
-
-
-
-
1999
0.6340
0.5209
0.6588
0.5835
0.464
0.333
Select
Select
1989
1990
1991
1992
1993
1995
1996
2000
Action
Avoid
Select
Select
Select
56
Appendix 0. Habitat selection of mountain big sagebrush cover types by radiomarked broodless female sage grouse with Bailey simultaneous confidence
intervals at HMNAR, 1989-2000.
Year
Lower 95%
Cl
Upper 95% Cl % Available
1989
0.3218
0.3449
0.044
Select
1990
1991
0.2280
0.1629
0.2492
0.1906
0.266
0.175
1992
0.1624
0.1872
0.278
Avoid
Neutral
Avoid
1993
-
-
-
-
1995
1996
0.1236
0.1872
0.1634
0.2303
0.416
0.225
Avoid
Neutral
1997
0.3225
0.3595
0.188
Select
1998
-
-
-
-
1999
0.0545
0.1748
0.0670
0.2253
0.088
0.183
Avoid
Neutral
2000
Action
Appendix P. Habitat selection of other cover types by radio-marked broodless
female sage grouse with Bailey simultaneous confidence intervals at HMNAR,
1989-2000.
Year
Lower 95%
Cl
Upper 95% Cl % Available
Action
1989
0.1092
0.1250
0.026
Select
1990
1991
1992
0.0583
0.0325
0.0263
0.0705
0.0467
0.0378
0.148
0.157
0.205
Avoid
Avoid
Avoid
1993
-
-
-
-
1995
1996
1997
0.0363
0.0317
0.0587
0.0607
0.0532
0.0785
0.115
0.069
0.093
Avoid
Avoid
Avoid
1998
-
-
-
-
1999
2000
0.0545
0.0088
0.0670
0.0250
0.065
0.084
Neutral
Avoid
57
Appendix Q. Habitat selection of Wyoming big sagebrush cover types by radiomarked broodless female sage grouse with Bailey simultaneous confidence
intervals at HMNAR, 1989-2000.
Year
Lower 95%
Cl
Upper 95% CI % Available
1989
0.0401
0.0504
0.026
Select
1990
0.0236
0.0318
0.097
1991
1992
0.0506
0.0003
0.0678
0.0008
0.075
0.060
Avoid
Avoid
Avoid
1993
-
-
-
-
1995
0.0008
0.0024
0.045
1996
0.0317
0.0532
0.036
1997
0.1015
0.1264
0.212
Avoid
Neutral
Avoid
1998
-
-
-
-
1999
0.0450
0.0523
0.0564
0.0842
0.179
0.128
Avoid
Avoid
2000
Action
Appendix R. Habitat selection of burned cover types by radio-marked broodless
female sage grouse with Bailey simultaneous confidence intervals at HMNAR,
1989-2000.
Year
Lower 95%
Cl
Upper 95% Cl % Available
Action
1989
1990
0.1269
0.2461
0.1437
0.2678
0.034
0.183
Select
Select
1991
0.1062
0.1296
0.169
Avoid
1992
0.2555
0.2845
0.180
Select
1993
-
-
-
-
1995
0.0792
0.1127
0.143
1996
0.1079
0.1431
0.266
1997
0.1451
0.1737
0.209
Avoid
Avoid
Avoid
1998
-
-
-
-
1999
0.1718
0.1423
0.1919
0.1892
0.204
0.272
Avoid
Avoid
2000