56 



151. Medica, P. A. 1967. Food habits, habitat preference, reproduc- 

 tion and diurnal activity in ^ sympatric species of whiptail lizards 

 (Cnemidophorus ) in south-central New Mexico. BULLETIN OF THE SOU- 

 THERN CALIFORNIA ACADEMY OF SCIENCES 66(4): 251-276. 



Three study areas near the Rio Grande are described and their ve- 

 getation characterized. Rainfall during one study year (1964) was the 

 lowest ever recorded at the NMSU weather station; rainfall during the 

 second study year (1965) was normal. Cnemidophorus exsanguis and _C. 

 inornatus preferred mesic habitats of saltgrass-tumbleweed and salt- 

 cedar-sal tbush during 1964; C_. neomexicanus and _C. tigris preferred 

 more xeric creosote-mesquite association habitats. All species became 

 more intimately associated throughout the study habitats during 1965. 

 All species except exsanguis expanded into habitats not occupied in 

 1964 and all species except tigris increased population density. Gra- 

 phic representations of food items for all 4 species are presented. 

 Lepidopterans were the most important food item for all 4 species. In- 

 terspecific competition is reduced by differential prey-size preferen- 

 ces and habitat preferences; neomexicanus and tigris are probably in 

 some competition because of similarities in both parameters. Changes 

 in food items consumed occurred from 1964 to 1965; consumption of lepi- 

 dopterans increased, that of ants decreased and that of termites ceas- 

 sed. _C. exsanguis laid only one clutch of eggs per year, the others 

 laid two. _C. exsanguis laid the most eggs and was the most numerous of 

 the 4 species. More males of the sexual species were present in the 

 population during July than females. Seasonal activity is described, 

 with immatures of all 4 species appearing first in the spring, adults 

 appearing by late May and disappearing by late August, and hatchlings 

 remaining active through September. No interspecific differences in 

 preferred temperatures were found. Seasonal daily activity is descri- 

 bed; lizards emerged when soil temperatures were 26-30°C. and disap- 

 peared when the soil temperature reached 50°C. It is suggested that 

 competition between neomexicanus and tigris is the likely reason the 

 former is distributionally limited primarily to the Rio Grande valley. 



152. — , G. A. Hoddenbach and J. R. Lannom, 3r. 1971. Lizard samp- 

 ling techniques. ROCK VALLEY MISC. PUBL. No. 1. 55 p. 



Basic techniques used in studying lizard population demographics, 

 including assessing population sizes and reproductive cycles, are pre- 

 sented and discussed. The unreliability of density estimates currently 

 based on walking transects is discussed. Cnemidophorus tigris is one 

 species illustrated. 



153. Mllstead, W. W. 1953. Ecological distribution of the lizards of 



