Environmental Characteristics and Functional Significance of Pronghorn Fawn Bedding Sites in Alberta

Abstract

Reduced recruitment and declining populations of pronghorns (A. americana) in Alberta prompted a study of bed-site selection by neonates. Characteristics of bedding sites of free-ranging fawns were studied on a 9300 km2 study area within the grassland range of southeastern Alberta. During 1971-1976, 465 bedded fawns, estimated mean age 2.8 days, were located and captured. Fawns commonly bedded on slopes, in native vegetation, in small depressions, on patches of bare ground, or adjacent to clumps of silver sagebrush (Artemisia cana), rock or cow dung. Many appeared to select sites that had characteristics that served as suitable vertical and horizontal sign stimuli, and thus stimulated bedding selection behavior. Sagebrush was sparse on the study area, and 75% of the fawns bedded on grassland ranges that had little or no brush cover. Wind velocity at fawn bedding sites was 59.5% less than readings taken 150 cm above the beds. No evidence of traditional fawning areas was found. The number of marked fawns relocated was used as an index of fawn survival. Estimated survival was higher for animals bedded in native range, and increased with greater cover density and use of depressions; significantly fewer fawns were relocated if they had been initially found bedded on cultivated land. Habitat diversity provided by silver sagebrush, small depressions and stands of grasses or forbs > 25 cm tall constituted important bedding cover, and contributed to above-average survival of fawns on the study area. Managers should recognize the value of these features when making land use decisions for this kind of rangeland.