Diet and Feeding Behavior of Teiid Lizards from Trans-Pecos, Texas

Abstract

Diet and feeding behavior of six species of Cnemidophorus occurring in Trans-Pecos Texas were studied over a three-year period. Comparative food data revealed that similar food items were utilized by all six species, but minor differences did occur that could be significant during adverse times. A dramatic shift in items consumed was documented for Cnemidophorus gularis as the activity season of 1968 progressed from the dry season into the wet season. Foraging behavior among sympatric species often represented a difference in methods of obtaining food which allowed species to exploit items, which although of the same general category, represented distinct differences in prey. A 3-year study was conducted on sympatric species of teiid lizards (Cnemidophorus) in the Trans-Pecos Region of Texas from June 1968 to August 1970. The study compared various aspects of competition and niche relationships in an effort to determine what factors are operating to preserve or break down species integrity within the genus. Natural hybridization between species of Cnemidophorus have been well documented (Wright and Lowe, 1967a) with the result sometimes giving rise to all-female parthenogenetic populations (Lowe and Wright, 1966; Wright and Lowe, 1967b). Part of the study involved dietary habits, including feeding behavior of sympatric species. Previous field studies indicate that two and often as many as four sympatric species of Cnemidophorus occur in the Trans-Pecos Region of Texas (Milstead, 1957, 1965; Degenhardt, 1966; Duellman and Zweifel, 1962). Milstead (1957, 1965) reported on the diet of three species of Cnemidophorus in the Black Gap area of Brewster County, Texas, and Medica (1967) compared the diet of four sympatric species of Cnemidophorus near Las Cruces, New Mexico. Two species, C. tigris marmoratus and C. inornatus heptagrammus, were present in both 1 Contribution No. 10058, of the Texas Agricultural Experiment Station.