60 



reproductive potentials appear to be the same. The geographic and eco- 

 logical distributions of whiptails in southwest Texas imply that, al- 

 though all ^ species are capable of living in most of the ecological 

 associations of the Chihuahuan Desert, no two of the species can simul- 

 taneously do so successfully. 



161. —. 1965. Changes in competing populations of whiptail lizards 

 (Cnemidophorus ) in southwestern Texas. AMER. MIDL. NAT. 73(1): 75-80. 



Population studies of _C. inornatus, _C. septemvittatus, and _C. 

 tigris done at the Black Gap Wildlife Management Area in 1952 were 

 repeated in 1962. The area had recovered from a severe drought during 

 that time span. Cnemidophorus tigris increased in density in the eco- 

 logical association it dominated in 1952 as well as in the associations 

 dominated by the other two species. Population estimates were 17.85 

 /acre and 7^.3/acre for 1952 and 1962, respectively. The two other 

 species were quite rare in 1962. Changes in diet are documented; lepi- 

 dopteran larvae had increased and termites decreased in importance. 

 The evidence suggests a tigris "bloom" and superior short-term compe- 

 ting ability over the other two species based on sheer numbers. _C. _in- 

 ornatus and _C. septemvittatus are relegated to more xeric, less produc- 

 tive habitats. 



162. — . 1977. The Black Gap whiptail lizards after twenty years, 

 in TRANSACTIONS OF THE SYMPOSIUM ON BIOLOGICAL RESOURCES 

 "OF THE CHIHUAHUAN DESERT REGION, UNITED STATES AND MEXICO. 

 Wauer, R. H. and D. H. Riskind, editors. National Park Service Trans- 

 actions and Proceedings Series No. 3: 523-532 



The Black Gap area was revisited in 1971 and 1972. The increased 

 rainfall trend has continued. The population density of Cnemidophorus 

 tigris has fallen from 1962 to 13.6^+ lizards per acre, and C. inornatus 

 and C_. septemvittatus have returned to their old habitats. An increase 

 in groundcover and predation are two hypotheses advanced for the popu- 

 lation phenomenon in _C. tigris . Natural cyclic events and the ability 

 of _C. tigris to "bloom"~take best advantage of short-term favorable 

 events better than other species of Cnemidophorus— are also discussed. 

 Changes in diet over the two decades are discussed. It is concluded 

 that termites are the staple food for Cnemidophorus during lean months 

 and/or years, but not during periods of abundant food variability and 

 availability. 



163. — , 3. 5. Mecham and H. McClintock. 1950. The amphibians and 

 reptiles of the Stockton Plateau in northern Terrell County, Texas. 

 TEXAS JOURNAL OF SCIENCE 2(^): 5if3-562. 



