Effect of Snow Depth on Mule Deer in Middle Park, Colorado

Autor: R. Bruce Gill, O.C. Wallmo, Paul F. Gilbert
Rok vydání: 1970
Předmět:
Zdroj: The Journal of Wildlife Management. 34:15
ISSN: 0022-541X
DOI: 10.2307/3799486
Popis: The distribution of mule deer (Odocoiless hemionus) on tSheir winter range in Middle Park, north-cenbal Colorado, is largely governed by snow depi. Snow over 18 inches deep essentially precludes deer use. In two of three winters of study, over 90 percent o£ the winter range was excluded from use because of snow. Fluctuations m winter deer counts were negatively correIated with NovemberFebruary precipitation. EFFECT OF SNOW DEPTH ON COLORADO DEER * Gxlbert et al. 15 northern Alaska. Univ. Kansas. Museum Nat. Hist. Misc. Pub. No. 8. 309pp. Bos, G. N. 1967. Range types and their utilization by muskox on Nunivak Island, Alaska; A reconnaissance study. WI.S. Thesis Univ. Alaska, College. 113pp. Photo offset. BUCKLEY J. L., D. L. SPENCER, AN:D P. ADAMS. 1954. Muskox (Ovibos moschatus) longevity. J. Mammal. 35(3):456. HONE, ELIZABE@1H. 1934. The present status of the muskox in arctic North America and Greenland. Am. Comm. for Internatl. Wildl. Protection Spec. Pub. No. 5. 87pp. KLIEN D. R. 1967. The introduction, increase and crash of reindeer on St. Matthew Island. J. Wildl. Mgmt. 32(2):350367. PALMER, L. J. 1938. Management of muskoxen and reindeer on Nunivak Island7 Alaska. Unpubl. Rept. Bur. Sport Fisheries and Wildl., Juneau. 2Spp. Mimeo. , AND C. H. ROUSE. 1936. Progress of muskoxen investigations in Alaska, 193>1935. Unpubl. Rept. Bur. Sport Fisheries and Wildl., Juneau. 35pp. Mimeo. , AND . 1945. Study of Alaska tundra with reference to its reactions to reindeer and other grazing. U. S. Fish and Wildl. Serv. Research Rept. No. 10. 48pp. ROUSE, C. H. 1948. Muskoxen on Nunivak Island, 1948. Unpubl. Rept. Bur. Sport Fisheries and Wildl., Juneau. 9pp. Mimeo. SCHEFFER, V. B. 1951 The rise and fall of a reindeer herd. Sci. Monthly 73(6):35S362. TENER, J. S. 1965. Muskoxen in Canada. Queens Printer, Ottawa. 166pp. U. S. GOVERNMENT, BUR. SPORT FISHERIES AND WILDL. 1947-1968. 34 misc. unpubl. repts. on file Washingtonn D. C., Bethel and Anchorage, Alaska. VIBE7 C. 1967. Arctic animals in relation to climatic fluctuations. Meddelelsen om Gr0nland. 170(5):15>162 and 181-lD2. Received for publicstion May 27, 1969. Winter is the critical time of year for big game animals over much of the Northern Hemisphere. In general, two factors are primarily responsible for this fact: ( 1 ) forage nutritional quality and abundance are at their lowest, and (2) snow limits the amount of range accessible for use. In the central Rocky Mountains, where mule deer winter in valleys above 7,00() ft) deer dieoffs of considerable magnitude occur in 1 A contribution of Colorado Division of Game Fish and Parks, Pittman-Robertson Project W-38-R) and Rocky Mountain Forest and Range Experiment Station, U.S.D.A. Forest Service. inter is the critical time of year fo big seve e winters. Because starvation is presumed to be ffie predominant eause of deaths) it is believed that forage yields on the winter range are inadequate and that management must be directed at increasing and maintaining adequate winter forage It does not follow ffiat all of the winter range is inadequate, but portions of it may be critical to the maintenance of deer populations. It is important to know what factors determine where this critical range is, so that appropriate priorities can be set in range management planning. Snow, as it hinders the movement of This content downloaded from 157.55.39.17 on Thu, 01 Sep 2016 05:13:44 UTC All use subject to http://about.jstor.org/terms 16 Journal of Wildlife Management, Vol. 34, No. 1, January 1970 animals and restricts the availability of forage, has a paramount influence. It was the opinion of Severinghaus ( 1947:220) that, while other factors of weather severity and characteristics of snow influence winter mortality, ". . . in the Adirondacks region, snow depth is the eritical weather factor affecting winter mortality among deer." Loveless ( 1967 ) considered the depth of snow to be the principal deterrent to use of forage by mule deer on the East Slope of the Roeky Mountains in Colorado. The effects of snow upon annual differences in distribution of winter use and deer survival in Utah were discussed by Robinette et al. ( 1952) . Snow as it influences the availability of forage to big game is also discussed by Hosley ( 1956 ), Smith ( 1954 ), and Cowan (1947). Edwards (1956) linked major fluctuations in big game populations in western Canada to snow depths. In Russia, Abramov (1959) attributed population declines of Altai wapitis and wildboar (Cersus elaphus and Sus scrofa) to heavy snowfall. In a cooperative research program of the Colorado Division of Game, Fish and Parks and the U.S.D.A. Forest Service, an initial effort was made to characterize the influence of snow on deer distribution in Middle Park, north-central Colorado. Some of the results reported here are derived from data separately collected by the Division of Game, Fish and Parks since 19154. STUDY AREA AND METHODS Middle Park (Fig. 1) is in the drainage of the Colorado River. Except for the narrow outlet through Gore Canyon, at 7,300 ft elevation, the Park is hemmed by mountain ranges varying from 9,000] 13,000 ft. Coniferous forest predominates above 9,OOiO ft. The unforested area below this elevation is vegetated predominantly with big Fig. 1. Middle Park and location of intensive study areas. s.agebrush (Artemisxa tridentata). The January average minimum temperature is 4.7 F at the Hot Sulphur Spring.s weather station. Snow depth varies with elevation, exposure, and gradient; while it sometimes exceeds 2 ft at lowest elevations, southerly exposures or wind-exposed sites at those levels are seldom snow-covered throughout the winter. With very few exceptions, deer spend the summer above 9,000 ft. Downward migration begins usually in late October when snow begins to accumulate on the summ.er range. Approximately 11,00012,000 deer wintered in Middle Park in the winter of 196748. These studies were conducted (a) over Middle Park in general, (b) in the vicinity of Sulphur Gulch where deer distribution varies considerably from year to year, and This content downloaded from 157.55.39.17 on Thu, 01 Sep 2016 05:13:44 UTC All use subject to http://about.jstor.org/terms EFFECT OF SNOW DEPTH ON COLORADO DEER * Gilbert et al. 17 (c) on Cedar Ridge where winter deer use is more or less constant.
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