30 



A comprehensive review of the literature on this species is pre- 

 sented. This species belongs to a genus that primarily inhabits de- 

 serts or other arid regions. It penetrates far to the north and east 

 of its congeners in the United States, into a region which under orig- 

 inal conditions was chiefly deciduous forest. It exists partly in dis- 

 junct populations selecting mainly xeroseral habitats such as beaches, 

 sand dunes and the edges of cultivated fields. It seems to require 

 open areas wherever it lives. The species is abundant in the sandy 

 floodplain of the Kansas River. A flood in 3uly of 1951 inundated the 

 area and destroyed the population, which did not recover its former 

 numbers for several years. A population was studied for a period of 9 

 years on the University of Kansas Natural History Reservation. Deeply 

 eroded gullies in fallow fields, heavily grazed pastures and exposed 

 rock and soil of a limestone quarry provided excellent habitats and 

 lizards were numerous at the beginning of the study. Vegetational suc- 

 cession proceeded as the area was protected and the population declined 

 as open habitats were reduced. The study was terminated when lizards 

 became few in number and no significant new data was being accumulated. 

 Seasonal activity began in April, peaked in 3une, then abruptly fell 

 off from July through September. Daily activity was bimodal in hot 

 weather. Individual active body temperatures ranged from 38 to 42°C.; 

 lizards will tolerate 5° below and 2° above this range before seeking 

 shelter. Air temperatures were always below active body temperatures. 

 This wcis the last species of reptile to emerge from hibernation on the 

 study area. An individual male had an observed home range of .31 acres 

 although this figure is probably biased because the habitat was not 

 uniform; female home ranges were slightly smaller. Activity was con- 

 centrated in particular parts of individual home ranges. Lizards were 

 observed to make extremely long movements and shift home ranges during 

 drought years, when vegetation decreased and more habitat became suit- 

 able. Lizards dig burrows extensively in soil and beneath rocks when 

 they cannot use those abandoned by other animals. Burrows are defend- 

 ed. Vegetation is also used in which to seek temporary refuge. Food 

 habits from other parts of the species range are discussed; it is noted 

 that olfaction plays a major role with lizards frequently digging for 

 prey such as insect larvae. Copulatory behavior is described; mating 

 appears to be aggressive and promiscuous. There is sexual dimorphism 

 in body proportions and color. The sex ratio is 1:1. Gravid females 

 were first recorded late in May and recorded latest in mid-August. Two 

 clutches per year are probably laid; females mature sexually and lay 

 eggs during their first year of life. Clutches range from 1-6 eggs; 

 first-year females average 2.0 eggs/clutch while older females average 

 i^A. The earliest hatchlings emerge during the first 2 weeks of August 

 and the second clutch hatches during September. Hatchlings average 32- 

 35 mm snout-vent length and weigh about one gram. The most successful 

 of them add 20 mm and come to weigh 1/2 of adult weight during the six 

 weeks before hibernation. Over-winter survivors reach adult size by 

 summer's end, although growth rates slow to 1/2 that of hatchlings. 

 The largest lizard measured, 5 years old, was S't mm SVL. Tail-break 

 frequency increases as lizards age, but even 1/2 of the largest and 

 oldest group retain original tails. No sexual difference is apparent. 

 The ultimate escape tactic is speed; however, lizards rely initially 



