Estimates of habitat carrying capacity incorporating explicit nutritional constraints

We offer an algorithm for estimating supportable densities of herbivores consuming diets at different levels of nutritional quality. We use this procedure to predict carrying capacity of burned and unburned mountain shrub habitat for mule deer (Odocoileus hemionus) and mountain sheep (Ovis canadensis) and compare our predictions with those of traditional range supply/animal demand models. Unburned areas had higher carrying capacities for animals consuming low quality diets, but burned areas could support more animals on a high plane of nutrition. Traditional procedures for estimating carrying capacity failed to detect these interactions between carrying capacity and animal nutritional status. We conclude that reliable evaluation of relationships between range food supplies and animal food requirements must treat forage amount and quality as integrated rather than distinct features of habitat.