Feeding ecology and niche separation in some native and domestic ungulates on the Shortgrass Prairie.
Diet selection studies of two wild species (Bison bison and Antilocapra americana) and domestic cattle and sheep were used to compare the ecological relationships between body size, the recent evolutionary history of the species and current forage conditions in northeastern Colorado, USA. Food niche breadth and inter-species diet overlap seemed dependent upon recent evolutionary history as well as upon body size, but values were strongly influenced by forage quantity and quality. Dietary selectivity appears especially sensitive to seasonal changes in forage quality. Sensitivity to diet composition and quality increased with decreasing size except in the domestic sheep. It is likely that anatomical-physiological adaptations, including a relatively large rumeno-reticulum allow domestic sheep to utilize more forage plant species and inhabit a wider variety of niches and ecosystems than most ungulates. Human selection has made sheep food and habitat generalists despite their relatively small size.<new para>ADDITIONAL ABSTRACT:<new para>In diet selection studies with domestic cattle and sheep, bison and pronghorn (Antilocapra americana), food niche breadth and inter-species diet overlap appeared to depend on recent evolutionary history and on body size, though values were strongly influenced by forage quantity and quality. Dietary selectivity was very sensitive to seasonal changes in forage quality, but body size and related nutrition/energy demands appeared to set limits as to when changes from selective to non-selective grazing tactics occurred. Sensitivity to diet composition increased with decreasing animal size except in sheep. In sheep, anatomical/physiological adaptations allowed them to utilize a larger number of forage spp. and inhabit more ecological niches than with other ungulates.