26th Annual Meeting and Symposium of the
Desert Tortoise Council, March 16-18, 2001
Abstracts

Desert Grassland and Tropical Deciduous Forest: Peripheral or Extralimital Desert Tortoise Habitats?

Brent E. Martin
University of Arizona, Ecology and Evolutionary Biology, Bio Sciences East, Tucson, AZ 85721

Desert grassland (USA and Mexico) and tropical deciduous forest (Mexico) delimit respectively the eastern and southern margins of the desert tortoises' distribution. Literature records document desert tortoises in these habitats, but they are bio-geographical communities where the species has received little attention. Are these continuous border entrant populations from immediately adjacent principle centers of distribution, i.e., Sonoran desertscrub and foothills thornscrub, or extralimital outliers? What prevents the species from further spreading into desert grassland and tropical deciduous forest? Topography is similar, and food and precipitation are perceptively greater than in those contiguous communities that are the principle population centers. Recent studies and observations of desert tortoises in desert grassland and tropical deciduous forest are discussed to help determine limiting factors controlling desert tortoise presence and abundance in these seemingly hospitable habitats.