Modeling temporal and spatial variation in pronghorn antelope population dynamics in southern Alberta in relation to environmental gradients

Abstract

The Grasslands Natural Region of Alberta is considered the most threatened ecosystem in the province. It provides habitat for numerous species of native plants and animals, including 75% of Alberta's 'species at risk'. Among the diversity of prairie wildlife, the pronghorn antelope (Antilocapra americana) is the most representative remaining large mammal. Pronghorn antelope are a highly valued resource in Alberta, experiencing high demand as big game species. However, in Alberta they are at the northern limit of their range and are susceptible to dramatic fluctuations in the population due to climatic extremes. The purpose of my research was to examine the key environmental drivers of pronghorn population dynamics in Alberta. I examined the influences of temporal and spatial variation in landscape composition, forage productivity, climate, coyote predation, and pronghorn density on pronghorn densitydistribution and population dynamics. Forage production, driven by moisture availability, and subsequent doe condition were key drivers of fawn production, while winter severity had a significant impact on population growth. The presence of native prairie had a profound positive influence on the spatial distribution of pronghorn, and influenced density-dependent effects on doe population growth and fawn production. I developed a generic system dynamics population model representing the key environmental and management factors that influence pronghorn population dynamics in Antelope Management Areas across Alberta. It was based on known empirical relationships supplemented with inferences and assumptions from published literature on pronghorn ecology. Recommendations for researching areas of key unknowns and reevaluating current management strategies are provided.