NESTING OR BEDDING 



POPULATION NUMBERS AND TRENDS 



Nesting habits of C. (G.) silus are almost 

 identical to those of Gambelia wislizenii (see 

 Parker and Pianka 1976). Females lay eggs in 

 June and July, in burrows at about 50 cm depth. 

 A chamber is excavated or enlarged, entrance tun- 

 nels sealed, and eggs are laid one at a time and 

 lightly covered with sand or soil. The exit tunnel 

 is then plugged from without. 



RITUAL REQUIREMENTS 



Males establish and defend home burrows, but 

 appear to have overlapping home ranges (Monta- 

 nucci 1965). The degree to which territoriality is 

 exhibited is probably correlated with abundance 

 and availability of food and cover; where mammal 

 burrows are abundant, individual home ranges 

 and home burrows are difficult to detect (Monta- 

 nucci 1965). Recently, Tollestrup (1979) found 

 that males defend home ranges, not just burrows. 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



Montanucci (1965) reported that several fac- 

 tors limit the distribution of C. (G.) silus: ; 



1. Agricultural practices 



2. Flooding 



3. Chaparral 



4. Steep or extensive rocky areas. 



Tall grass may hamper foraging and rapid loco- 

 motion, and may account for the relative scarcity 

 of C. (G.) silus on the east side of the San Joa- 

 quin Valley (Montanucci 1965). K. Tollestrup 

 (pers. comm.) reported that tall grass improves 

 foraging because insect abundance increases and it 

 gives the lizards cover for escape from predators. 

 Scarcity of C. (G.) silus in tall grass areas on the 

 east side of the San Joaquin Valley is probably 

 due to the fact that human settlements in this 

 region and farming and grazing of the land date 

 back many years. Also, in this area, it is common 

 practice to plow and burn rangelands in the fall, 

 which decreases or eliminates populations of C. 

 (G.) silus. Entomologists working in Kern County 

 reported finding leopard lizards killed by insecti- 

 cides (DDT and Malathion) (Montanucci 1965). 



J. M. Sheppard {in Snow 1972) estimates a 

 density of 300 to 400 Uzards per square mile of 

 optimum habitat near Maricopa, Kern County. 

 Since it is unlikely that all habitats occupied are 

 optimum, he considered the mean density of 

 lizards to be 100/mi' (38.6/km' or 0.4/ha). 

 Tollestrup (1979) estimated that there were 3.5 

 Uzards per ha at Pixley National Wildlife Refuge, 

 which is the highest known density. Populations 

 of C. (G.) silus are low (0.5 to 1 per acre or about 

 1 to 2.5 per ha) under optimum conditions 

 (Anon. 1978). 



REPRODUCTION 



The reproductive cycle varies slightly with 

 environmental conditions. Males will often mate 

 with several females. Mating occurs from late 

 April to early June; clutches of 2 to 5 eggs are 

 laid in June or July; some females may have two 

 clutches per year (Montanucci 1965). Incubation 

 time is estimated at about 57 days. Young (42 to 

 47 mm in snout-to-vent length) appear from July 

 30 through September. Sexual maturity in both 

 sexes occurs between 9 and 18 months (Mont- 

 anucci 1965, 1967; Tollestrup 1979). 



MANAGEMENT AND CONSERVATION 



Habitat for the blunt-nosed leopard hzard is 

 rapidly being lost throughout its range. In the 

 last 100 years, the natural wildlands of the San 

 Joaquin Valley have decreased from 3 million ha 

 to about 200,000 ha (Dickl977). Suitable habitat 

 (salt-brush desert scrub) on the west side of the 

 valley is now being developed for agriculture, 

 since completion of the California Aqueduct. 

 Also, off-road vehicles have denuded parts of this 

 region. 



R. R. Montanucci ( in Snow 1972) recom- 

 mended the establishment of a national grassland 

 preserve in the southwestern part of the San Joa- 

 quin Valley as the most rapid means of assuring 

 partial protection of this species. Erode (1978) 

 recommended protective management programs 

 on the remnants of suitable lizard habitat on 

 public lands (the Naval Petroleum Reserve near 

 Taft, the Kern and Pixley National Wildlife Re- 

 fuges, Los Padres National Forest, and National 



