Mineral content of Sonoran pronghorn forage

Our objective was to determine the mineral content of forage species availa ble for Sonoran pronghorn, Antilocapra americana sonoriensis, on the Cabeza Prieta National Wildlife Refuge (CPNWR) in southwestern Arizona. We measur ed vegetation abundance at 2 sites within Sonoran pronghorn range from June 1995 to May 1995 using the dry-weight-rank and comparative yield methods. We determined plant mineral contents for forage species and for species not consumed by pronghorn by collecting, freezing, drying, and analyzing veget ation samples for up to 15 species over 5 seasons. Quantities of minerals p resent in forage species used by pronghorn showed slight variability by sit e or season, and were not different in non-forage species. We constructed t heoretical diet models for pronghorn based on published literature and our field data. We used the models to describe dietary intake of plant dry matt er and minerals by pronghorn with and without selective use of forage. We c ompared predicted mineral intake by pronghorn to published requirements for domestic sheep. Diets consumed by pronghorn using plants available on the CPNWR were deficient in sodium, phosphorus, copper, zinc, and selenium.