Winter Habitat-Use Pattern of Elk, Mule Deer, and Moose in Southwestern Wyoming

Volume 47 Number 4 Article 24

10-31-1987

Winter habitat-use pattern of elk, mule deer, and moose in southwestern Wyoming

Olin O. Oedekoven University of Wyoming, Laramie

Fredrick G. Lindzey University of Wyoming, Laramie

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Recommended Citation Oedekoven, Olin O. and Lindzey, Fredrick G. (1987) "Winter habitat-use pattern of elk, mule deer, and moose in southwestern Wyoming," Great Basin Naturalist: Vol. 47 : No. 4 , Article 24. Available at: https://scholarsarchive.byu.edu/gbn/vol47/iss4/24

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. WINTER HABITAT-USE PATTERNS OF ELK, MULE DEER, AND MOOSE IN SOUTHWESTERN WYOMING

Olin O. Oedekoven'^and Fredrick G. Lindzey'

Abstract. —Habitat-use patterns of mule deer, elk, and moose were determined on two winter ranges near Kemmerer, Wyoming. Mule deer used areas with the least snow depth and dominated by sagebrush. Elk were located more often than expected on wind-swept hills but used sagebrush communities more frequently as snow depths increased. Moose were generally found associated with broad, riparian zones. All three species occasionally used the same area but differed in their use of specific vegetation types and topography.

Many winter ranges in the Rocky Moun- ter. The combined 1985 population estimates tains are used by two big game species, but for these areas were 20,000 mule deer, 2,700 few ranges support three or more species of elk, and 1,000 moose (Wyoming Game and large ungulates. Nelson (1981) suggested that Fish Department, unpublished files 1985). although mule deer (Odocoileus hemionus) The western wintering area is about 15 km and elk (Cervis elaphus) often share winter wide by 32 km long, and the eastern area is 28 ranges, these species compete for forage only by 46 km. Drainages generally flow from the during extreme environmental conditions. north to south and east to west within the His conclusions were based on the differing western area and west to east within the east- foraging strategies of mule deer and elk; elk ern area. Western exposures dominate the selected mostly grasses, while mule deer pre- western portion and eastern exposures the ferred browse species. Elk and moose {Alces eastern area. Elevations vary from 2,800 m to alces) relationships on winter ranges were 1,800 m. Annual precipitation ranges from 25 evaluated by Stevens (1974), Nelson (1981), to 35 cm, gradually shifting to less than 25 cm and Rounds (1981). These authors concluded in the more xeric eastern portions of the win- that because elk and moose occupied unique ter range. Average growing season is 60-90 habitats and exhibited differing diets, they days (Bureau of Land Management, Kem- were not usually competitors. Moose and elk merer Resource Area, unpublished files). appear to fill two discrete ecological niches Sagebrush {Artemisia spp.) rangeland with respect to range, food habitats, physical (Lanka et al. 1983) characterizes the majority characteristics, and social organization. of both winter ranges. This shrub vegetation

The purpose of this study was to document type is composed of big sagebrush (A. triden- the winter distribution of three ungulate spe- tata), with lesser amounts of black sagebrush cies on two adjacent winter ranges and to (A. nova), saltbushes {Atriplex spp.), and identify habitat characteristics associated with black greasewood {Sarcobatus vermiculatus). the distribution of each species. Mixed-shrub communities are found on more

mesic sites. This community is dominated by Study Areas Utah serviceberry {Aynelanchier utahensis), western snowberry {Symphoricarpos occi- The study included a majority of two large, dentalis), and antelope bitterbrush {Pursha adjacent big game winter range complexes in tridentata). Quaking aspen {Populus tremu- southwestern Wyoming (Wyoming Game and loides)sLre present in small (< 0.5 ha) stands at Fish Department, unpublished files 1983). higher elevations. Willow (Salix spp.) and The two winter ranges are separated by high- grass meadows dominate the larger river bot- elevation mountains (3,500 m) that receive toms. Pockets of mixed conifers dominated by little or no use by ungulates during midwin- Engelmann spruce {Picea engehnannii) and

University of Wyoming Cooperative Fish and Wildlife Research Unit, Box 3166 University Station, Laramie, Wyoming 82071. ^Present address: Wyoming Game and Fish Department, 2800 Pheasant Drive, Casper, Wyoming 82604.

638 October 1987 Oedekoven, Lindzey: Winter Habitat in Wyoming 639

subalpine fir {Abies hisiocarpa) are common Estimates of availability of the various vege- on the steep, usually northern exposures of tative communities, topographic, and snow- the higher-elevation ridgelines. An extensive condition categories were obtained by making stand of curl-leaf mountain mahogany {Cerco- observations at intervals of three nautical carpus ledifolius) is present on the northwest- miles during aerial surveys. Data were ern portion of the western winter range. Ju- recorded for the availability site (about 50 x niper (Juniperus spp.) stands are infrequent 50 m) in the same manner as that used when and limited to small (< 0.25 ha) pockets. animals were observed. Characteristics of Higher ridges that are devoid of shrubs are sites where animals were observed were com- generally vegetated by mosses, lichens, and pared to estimates of availability using Chi- warm-season grasses (Poaceae). square tests of independence (Khazanie 1979) Most of the land in both winter ranges is with the Mine Tab computer program (Ryan administered by the Bureau of Land Manage- et al. 1985). Spatial overlap of species was ment or the State of Wyoming. Principle land examined by simply comparing counts of spe- uses include grazing by cattle and domestic cies present in 1.6-km" grids. These grids sheep and energy exploration and extraction. were positioned on section, range, and town- ship boundaries. Methods

Aerial Surveys Evaluation of Potential Sampling Biases

Flights w^ere conducted over the winter Making inferences from observation data ranges during December and January of each about dispersion or habitat-use patterns re- year. A highly modified Maule N5AR single- quires that several assumptions regarding ani- engine, fixed-wing aircraft (Stockhill 1986) mal detectability be met. Animals should be was used to fly 0.9-km-wide, established tran- equally or proportionately detectable sects. Transects were located to provide com- throughout the sampled area (species and in- plete and consistent coverage of the winter dividuals). To evaluate the possibility that range. Animal locations were recorded on an deer, elk, and moose were more easily de- onboard computer interfaced with an area tected from the airplane when standing or navigational system. Locations were recorded bedded or in specific vegetation types, we in precise latitude and longitude coordinates conducted surveys on the ground after each as the aircraft flew over each animal group flight. We located animals by searching with a (one or more animals). This navigational sys- truck or snowmobile or driving to areas where tem also allowed the same predetermined they had been observed from the airplane. transects to be flown each month. Once we located an animal or group of animals, we visited them periodically through Data Collection the day and noted the activity (standing or Vegetation type, topography, exposure, bedded) and habitat type for each animal. Ob- snow depth, snow cover, and animal activity servations were not begun for at least 0.5 hr were recorded for each observation. Vegeta- after the group was first located to minimize tion-type categories included sage-grass, the possibility that they were located because mixed shrub, aspen, willow, mountain ma- of their activity or the vegetation type in hogany, mixed conifer, alpine grass, and agri- which they were initially found. Results of cultural areas. Topographic categories were: ground surveys were compared with results of drainage (draws, ditches, and narrow the airplane transects to identify differences canyons), flat (less than 5% slope), toeslope that would suggest differential detectability. (slope base to 30 m up a slope), steep (20-h% Additionally, we searched areas on the slope), ridgeline, and hilltop. Exposure cate- ground for animals and their sign where no gories were one of the eight cardinal direc- animal had been observed from the air. On tions. Snow conditions were estimated for the five occasions we walked or drove through area occupied by an animal group and in- dense vegetation types (i.e., sagebrush cluded snow depth and percent snow cover. draws, mountain brush stands) and attempted Estimates of snow depth were subjective and to count the animals present for comparison based on height of plants and animals. with counts made from the air. 640 Great Basin Naturalist Vol. 47, No. 4

Table 1. Mule deer, elk, and moose observed during aerial transects and ground surveys in southwestern Wyoming, 1984-1986. October 1987 Oedekoven, Lindzey; Winter Habitat in Wyoming 641

Table 3. Percent of mule deer, elk, and moose observations in the various topographic categories during the winters of 1984-85 and 1985-86 and estimates of availahihty as determined from monthly aerial sampling. 642 Great Basin Naturalist Vol. 47, No. 4

Table 5. Percent of mule deer, elk, and moose observations in the various snow-condition categories during the winters of 1984-85 and 1985-86 and estimates of availability as determined from monthly aerial sampling. October 1987 Oedekoven, Lindzey: Winter Habitat in Wyoming 643

dery, allowing fairly unrestricted movement Gilbert, P F , O C Wallmo, and R B Gill 1970. Ef- by moose. fect of snow depth on mule deer in Middle Park, Colorado. J. Wildl. Manage. .34(1); 15-23. Our results suggested that although deer, Kelsall, J P 1969. Structural adaptations of moose and elk, moose often used the same areas, and deer for snow. J. Mammal. 50(2): 302-310. they selected differing habitats within shared Khazanie, R 1979. Elementary statistics in a world of areas. These patterns might be expected to applications. Good Year Publ. Co., Santa Monica, California. 488 pp. change with deeper snow as suggested by CliflF Lanka, R P , D B. Inkley, and S H Anderson 1983. (1939). The greatest spatial overlap of elk and Wyoming and Montana land cover classification mule deer occurred during January of the first and mapping project. Final Rept., U.S. Dept. winter and December of the second, the Inter., Fish and Wildl. Serv., Wyoming Fish and Wildl. Coop. Res. Unit, Laramie. 33 2 maps. months with the greatest snow depths (Table pp.,

LeResche, R E , and R A Rausch. 1974. Accuracy and 2). Because of the dominant use and availabil- precision of aerial moose censusing. J. Wildl. ity of the sagebrush vegetation type, slightly Manage. 38(2): 175-182. underestimating deer use of mixed-shrub Nelson, J R 1981. Relationships of elk and other large herbivores. Pages 415-441 in W. Thomas and vegetation from the airplane would not J. D. E. Toweill, eds.. Elk of North America: ecol- demonstrably alter the results presented. ogy and management. Stackpole Books, Harris- burg, Pennsylvania. 698 pp. Acknowledgments Nelson,] R.andT A Leege, 1981. Nutritional require- ments and food habits. Pages 323-367 in J. W. Thomas and D. E. Toweill, eds.. Elk of North We would like to express our gratitude for America: ecology and management. Stackpole the cooperative efforts of the Wyoming Game Books, Harrisburg, Pennsylvania. 698 pp. Peek, 1974. the nature of winter habitats of and Fish Department, the Bureau of Land J M On Shiras moose. Nat. Canadienne 101: 131-141. Management, and the University of Wyo- Rounds, R. C 1981. First approximation of habitat selec- ming. E. Raper was instrumental in the suc- tivity of ungulates on extensive winter ranges. J. cess of the project. Funding for the project Wildl. Manage. 45(1): 187-196. was provided by the Wyoming Game and Fish Ryan, B F , B L Joiner, andT A Ryan, Jr 1985. Minitab handbook. Sec. Rd. Dusbury Press, Boston. 374 Department, and it was conducted under the pp. auspices of the Wyoming Cooperative Fish- Smith, J, G 1952. Food habits of mule deer in Utah. J. ery and Wildlife Research Unit. Wildl. Manage. 16(2): 148-155. Springer, L. M 1950. Aerial census of interstate antelope

herds of California, Idaho, Nevada, and Oregon. J. Literature Cited Wildl. Manage. 14(3): 295-298. Stevens, D. R 1974. Rocky Mountain elk-Shiras moose Beall, R C 1974. Winter habitat selection and use by a range relationships. Nat. Canadienne 101(4): western Montana elk herd. Unpubhshed disserta- 505-516. tion, University of Montana, Missoula. 197 pp. Stockhill, M E 1986. The making of a microchip Cliff, E P 1939. Relationship between elk and mule Maule. Aero (10): 18-25. deer in the Blue Mountains of Oregon. Trans. N. Wilkins, B T 19.57. Range use, food habits, and agricul- Amer. Wildl. Conf. 4: 560-,569. tural relationships of the mule deer, Bridger

COADY. J W. 1974. Influence of snow on behavior of Mountains, Montana. J. Wildl. Manage. 21(2): moose. Nat. Canadienne 101: 417-436. 1,59-169.