135. McCoy, C. J., Jr. 1965. Life history and ecology of Cnemido - 

 phorus tigris septentrionalis . PH.D. DISS., UNIV. OF COLORADO. 178 p. 



11 populations in a variety of ecological situations below 6000 

 feet in the valleys of major river systems were studied for 3 seasons 

 in Colorado. This distribution results from recent dispersal up desert 

 corridors. Pure stands of Sarcobatus vermiculatus and pinyon-juniper 

 woodlands on sandy soils are preferred. Morphology is discussed. The 

 most important food items are Lepidopteran larvae, Coleoptera, Orthop- 

 teran nymphs, and spiders. Seasonal shifts in food items are the result 

 of changing acceptibility and availability of prey and a rigid prey size 

 selection standard. Adults and subadults utilize significantly differ- 

 ent food sources. Evidence of predation is lacking although 15% of ad- 

 ults have had broken tails. Soil temperatures exert the basic control 

 on daily activity cycles. Seasonal activity lasts from early May until 

 late September. Individual adult males are active for only 60-75 days; 

 females are active for 75-90 days. Lizards spend the inactive season in 

 self-constructed burrows. The reproductive cycle is discussed. Hatch- 

 lings average a snout-vent length of 37 mm. Adult size is reached in 

 13-1^^ months and reproductive maturity in 22 months. One clutch per 

 year is laid averaging 3A eggs (ranging from 2.9-3.9 and increasing 

 with age). Home ranges are not defended and overlap broadly; that of 

 males is larger than that of females. Both size and complexity of home 

 range increase with a lizard's age. A density of 7 lizards/acre was 

 measured for one study area. The sex ratio is 60:40 in favor of males; 

 this is attributed to increased mortality of females during their longer 

 active season. Individual ecological life expectancy is 6 seasons, 4 as 

 a reproductive. The annual replacement in the breeding population is 

 less than 20% (from abstract). 



136. — . 1968. Food selection and age-class competition in Cnemi- 

 dophorus tigris . JOURNAL OF HERPETOLOGY 1(1-1): 118. 



Seasonal changes in the proportions of food items eaten are re- 

 ported for _C. t. septentrionalis in western Colorado. Adult and sub- 

 adult lizards depend on significantly different parts of the local prey 

 population. The reduction of food competition permits a large annual 

 class of sub-adults to exist, and provides for a more resilient popula- 

 tional response to short-term environmental fluctuations. 



137. — . 1971. Communal hibernation of the lizard Cnemidophorus 

 tigris (Teiidae) in Colorado. SOUTHWESTERN NATURALIST 19(2): 218. 



3 lizards were found together in a burrow, which is described. 

 This phenomenon is suggested to be a response to extreme winter temp- 



