Nutritional Significance of Wapiti (Cervus Elaphus) Migrations to Alpine Ranges in Western Alberta, Canada

Abstract

This study was designed to provide a better understanding of the nutritional significance of wapiti (Cervus elaphus) migrations from low-elevation winter ranges onto high-elevation alpine summer ranges. The study focused on a population along the east slopes of the Rocky Mountains in western Alberta.

Food habits analysis of the study population shows that diets consisted largely of grasses on winter (90%), spring (71%), and fall (72%) ranges. On alpine summer ranges, willows were the dominant dietary component (89%). The yearly cycle of forage quality on seasonal ranges showed that wapiti face low forage nitrogen concentration for seven months. In winter (December-April), wapiti foraged on grasses that were more digestible than willows (67% vs. 51%), but did not meet maintenance nitrogen requirements. From May to July, by moving first onto spring ranges and then onto summer alpine ranges, wapiti had access to forage sufficient to provide nutrient requirements for maintenance, pregnancy, and lactation. On alpine ranges, by shifting their diet to willow leaves, wapiti selected for forage with high crude protein content (16.8%) despite the apparent lower digestibility. Total fecal nitrogen content was correlated (r²= .90) with the estimated nitrogen content of the diet. The use of spring and summer ranges coincided with a period of higher forage quality in those areas.