61 



Eleven habitat associations are described for the plateau, which 

 is considered to lie in the northeastern portion of the Chihuahuan Bio- 

 tic province- Cnemidophorus grahamii (= tesselatus ) was taken mostly 

 in cedar-ocotillo at the base of mesa slopes or in mesquite-creosote 

 not far from its margin with the former association. Both are charact- 

 erized by extensive rock and sparse vegetation. Cnemidophorus gularis 

 gularis and _C. perplexus i- inornatus ) were found in cedar savannah of 

 mesa tops and mesquite-creosote of the broad inter-mesa valleys. The 

 former species was more common than the latter. The habitats occupied 

 by these two species were characterized by good vegetative cover, al- 

 most impenetrable in places, and little rock. 



16*. — . and D. W. Tinkle. 1969. Interrelationships of feeding ha- 

 bits in a population of lizards in southwestern Texas. AMERICAN 

 MIDLAND NATURALIST 81(2): ^91-^99. 



An analysis of food items eaten by Cnemidophorus tigris marmora - 

 tus is given. It is an opportunistic feeder on arthropods, predomin- 

 ately coleopterans and orthopterans. Competition with the other dom- 

 inant lizard species present, Uta stansburiana , is avoided through the 

 exploitation of different size-classes of prey. Interspecific compe- 

 tition for food is one explanation for the rarity of other lizard spe- 

 cies in the study areas. 



165. Minton, S. A., Jr. 1958. Observations on amphibians and rep- 

 tiles of the Big Bend region of Texas. SOUTHWESTERN NAT. 3: 28-5^. 



Cnemidophorus tigris marmoratus is very plentiful on desert flats 

 and sandy areas along the Rio Grande. It is less abundant in foothills 

 and rare or absent in prairie areas or elevations above 5000 feet. In- 

 traspecific aggression was noted. jC. tesselatus was spotty in occurr- 

 ance and evidently restricted to arid mountains, mesas and canyons. 

 All specimens examined are females; no males have ever been found. C. 

 sacki exsanguis and gularis (= _C. exsanguis and _C. gularis ) occur on 

 low, slightly damp, grassy sites and on hills in the sparse juniper- 

 cholla-sotol association. They show no tendency to frequent rocky 

 sites. _C. perplexus (= inornatus ) occupies prairie, desert flats and 

 desert foothills; it does not occur on higher mountains or the Rio 

 Grande lowlands. It is the dominant lizard in flat, open spaces almost 

 devoid of vegetation. It likes grass and mesquite; it is absent from 

 Larrea and yucca associations. 



166. Mitchell, J. C. 1979. Ecology of southeastern Arizona whiptail 

 lizards (Cnemidophorus : Teiidae): population densities, resource parti- 

 tioning, and niche overlap. CANADIAN 3. ZOOLOGY 57: 1^87-1^*99. 



