Lizard Community Response to a Desert Shrubland-Intertidal Transition Zone on the Coast of Sonora, Mexico

The Sonoran coast of Mexico is characterized by an abrupt transition from marine bay to inland desert. We surveyed lizard species along 141 transects in desert shrubland, desert-dune scrub transitional, dune scrub, and sandy intertidal habitat areas within this transition zone. Cnemidophorus tigris, Uta stansburiana, and Callisaurus draconoides accounted for > 99% (N = 353) of individuals identified. Cnemidophorus tigris was almost entirely restricted to desert shrubland, U. stansburiana was mostly restricted to desert shrubland and desert-dune scrub transitional habitats, and C. draconoides was the most generalized in habitat use. It exhibited strong preferences for bare ground and was the only species observed in the sandy intertidal zone, an area devoid of vegetation. The intertidal zone had the highest lizard biomass of the four habitats but was completely dominated by a single species. Total lizard density and biomass were substantially less in desert shrubland, but lizard diversity was greatest in this structurally complex habitat. We suggest that habitat structure regulates lizard diversity, whereas food resources control lizard density across the transition zone.