Foods of the Desert Tortoise, Gopherus agassizii, in Arizona and Utah

Abstract

The diet of the desert tortoise, Gopherus agassizii, was determined from three areas at the base of the Grand Wash Cliffs above Lake Mead, Arizona, from an area in the New Water Mountains, Arizona, and from the central Beaver Dam Wash, Utah. Thirty-two kinds of plants, bird feathers, mammal hairs, snake and lizard scales, and arthropod parts were classified from the microhistological analysis of fecal droppings from desert tortoises. Foxtail brome, globemallow, slim tridens and threeawn made up > 80% of the tortoise diets from the Grand Canyon areas. Threeawn, slim tridens, bush muhly and slender janusia made up > 90% of the diets from the New Water Mountains. Foxtail brome and redstem filaree made up > 80% of the tortoise diets from the Beaver Dam Wash area