Pronghorn Antelope Range Characteristics and Food Habits in Alberta

Abstract

Range productivity, vegetation characteristics, and food habits of the pronghorn antelope (Antilocapra americana) were studied in the Pakowki and Newell areas, Alberta, frotn 1962 through l9B5. Quantitative measurements of canopies, frequencies, constancies olf taxa, and yields of plant categories showed that the Pako!wki and Newell areas represented spear grass-westem wheat grass/blue grama ( Stp forbs in all seasons; and grasses and sedges in spring. Cultivated grain was of minor importance In the Pakowki area browse species and grasses and sedges were the most important food categories in late fall and early winter. The five major food items, comprising 73 percent of the total diet in the Newell area, were silver sagebrush ( Artemsa cans ), pasture sagewort ( A. frigida ) > grasses and sedges, ball cactus ( Mamillaria visipara ), and western snowberry ( Symphoricarpos occidentalz )) in order of decreasing volume. These same species comprised 90 percent of the diet of antelopes in the Pakowki area in late fall and early winter. Comparisons between vegetation abundance and antelope food habits in two areas in 1964 indicated that both forbs and browse species are preferred foods, and that forbs, when available, are eaten in preference to grasses and sedges. Silver sagebrush and pasture sagewort are key antelope foods irl the Newell area? comprising 82 percent of the winter diet, and over one-half the diet at all times except summer. Silver sagebrush, western snowberry? and graminaceous species are the key foods in the Pakowki area in fall and early winter. The role and importance of big sagebrush (Artemisuz triderttsta) in the diet cf anteiopes south of latitude 49° N is assumed by silver sagebrush and pasture sagewort in the diet of antelopes in Alberta. The area occupied by the pronghorn antelope in North America has been considered to be divisible into two major regions on the basis of land productivity and on the factors that regulate antelope numbers (Buechner 1961). According to this classification, the steppe of southern Alberta is located in that region characterized by relatively moist conditions, high land productivity, and the regulation of antelope numbers by man. Published information on range productivity and antelope range use in Canada and adjacent states is limited. Dirschl ( 1963 ) reported on the major food plants eaten seasonally by antelopes on mixed prairie and fescue grasslands in Saskatchewan. Cole (1956:1S33), and Cole lPresent address: Biology Department, University of Saskatchewan, Regina Campus7 Regina. 238 and Wilkins (1958:92S) deseribed range and food habits of antelopes in Montana with referenee to alfalfa ( Medicago sativa ) and winter wheat ( Triticum aestivom ) produetion, respeetively. Bayless (1969) presented a detailed aeeount of winter range, range use and food habits of the pronghorn in eentral Montana. These Montana studies, those for Califoinia ( Ferrel and Leaeh 1950), those for Oregon and Nevada (Mason 1952)) and those for other regions report orl the importance of big sagebrush in the diet of the pronghorn. The absenee of this plant speeies on antelope ranges in Canada raises the question as to what speeies or eombination of speeies supplants this important food item in the diet of pronghorns in Alberta. Our study, condueted from 1962 through 1965 on two antelope ranges in southern This content downloaded from 157.55.39.231 on Wed, 05 Oct 2016 04:22:43 UTC All use subject to http://about.jstor.org/terms FOOD HABITS OF ANTELOPES * Mitchell and Smolulk 239 Alberta, was designed to measure land productivity, vegetation characteristics, vegetation changes, and their influence on antelope diets. We thank R. G. H. Cormack, Botany Department, University of Alberta, for his participation in l9B2; and T. W. Peters, Pedologist, Canada Department of Agriculture Soil Survey, University of Alberta, for his soil analyses in 1964. Thanks are also extended to L. G. Sugden, Canadian Wildlife Service, for critically reviewing the manuscript. The laboratory analysis of food materials was supported in part by a grant from W. A. Riddell, former principal, University of Saskatchewan, Regina Campus; and by National Research Council Grantin-Aid No. 3913.