Western Banded Gecko (Coleonyx variegatus)

Western Banded Gecko (Coleonyx variegatus)

Banded Gecko
General Distribution

The banded gecko exists in two forms in California. The desert banded gecko (C. v. variegatus) is common to uncommon in the desert from northern Inyo Co. south to Mexico. It is found from below sea level to 1500 m (5000 ft) in all desert habitats up to pinyon-juniper or mixed chaparral, but is most abundant in sandy flats and desert washes (Klauber 1945). The San Diego banded gecko (C. v. abbotti) occurs in coastal and cismontane southern California from interior Ventura Co. south, although it is absent from extreme outer coast. It is uncommon in coastal scrub and chaparral, most often occurring in granite or rocky outcrops in these habitats (Klauber 1945, Stebbins 1972).

Habitat Requirements

The desert banded gecko occurs in a wide variety of habitats, however the San Diego banded gecko prefers rocky or granite outcrops.

Reproduction

Mating occurs from April to May, eggs are laid from May through September, and hatchlings appear July through November (Stebbins 1954, Fitch 1970, Parker 1972, Miller and Stebbins 1964). Males emerge in April and attain peak testes size in May followed by testicular regression (Parker 1972). The highest frequency of gravid females was in May and June (Parker 1972). Clutch size is two eggs, one per ovary or oviduct. Eggs are sometimes laid one at a time on different days (Parker 1972). Females store sperm and can produce multiple fertile clutches per season (Mayhew 1968, Parker 1972). Two to three clutches per season are produced. Estimates of incubation time are 30 to 45 days. Males and females reach maturity within one year at 52 mm (2.08 in) and 56 mm (2.24 in), respectively (Fitch 1970, Parker 1972).

Daily/Seasonal Activity

Nocturnal. The peak activity period is two hours after sunset (Klauber 1945, Miller and Stebbins 1964), however, banded geckos may come out in the late afternoon to absorb heat (Brattstrom 1952). They are active April through October with a peak in May. Juveniles may be intermittantly active November through March (Klauber 1945, Parker 1972).

Diet and Foraging

Banded geckos are opportunistic foragers on insects and other arthropods including beetles, termites, spiders, grasshoppers, sowbugs, and insect larvae (Klauber 1945, Parker and Pianka 1974).

Territoriality/Home Range

Parker (1972) estimated densities of 12-25 geckos/ha (5-10 acre) in Arizona. By driving roads at night, Klauber (1945) found 19.4 per 160 km (100 mi) in the Borrego area in San Diego Co. On the best trips he encountered one gecko on the road every 3.2 km (2 mi), or 24 specimens in 78.4 km (49 mi). Aggressive interactions between males in the laboratory suggest the possibility of territoriality in the field, or may be a means of sex recognition in a species that is not sexually dimorphic. During the day geckos tended to aggregate in shelters in the laboratory (Greenberg 1943).

Predator-Prey Relations

Predators include leaf-nosed snakes, western patch-nosed snakes, night snakes, sidewinders, western diamondback rattlesnakes, coachwhips, and zebra-tailed lizards (Klauber 1945, Funk 1965, Parker 1972). Other possible predators are tarantulas, large centipedes, solpugids, other rattlesnake species, coyotes and foxes (Parker 1972). Tail autotomy is believed to be an important defense mechanism from enemies (Parker 1972, Parker and Pianka 1974). The tail is raised and undulated at the approach of a predator (Johnson and Brodie 1974).

Literature Cited

Brattstrom, B. H. 1952. The food of the night lizards, genus Xantusia. Copeia 1952:168- 172.
Dixon, J. R. 1970a. Coleonyx. Cat. Am. Amphibians and Reptiles 95.1-95.2.
Dixon, J. R. 1970b. Coleonyx variegatus. Cat. Am. Amphibians and Reptiles 96.1-96.4.
Fitch, H. S. 1970. Reproductive cycles in lizards and snakes. Univ. Kans. Mus. Nat. Hist. Misc. Publ. 52:1-247.
Funk, R. S. 1965. Food of Crotalus cerastes laterorepens in Yuma County, Arizona. Herpetologica 21:15-17.
Greenberg, B. 1943. Social behavior of the western banded gecko, Coleonyx variegatus Baird. Physiol. Zool. 16:110-122.
Huey, R. B., and E. R. Pianka. 1983. Temporal separation of activity and interspecific dietary overlap. Pages 281-290 in R. B. Huey, E. R. Pianka, and T. W. Schoener, eds. Lizard Ecology. Harvard Univ. Press, Cambridge. 501pp.
Johnson, J. A., and E. D. Brodie, Jr. 1974. Defensive behavior of the western banded gecko, Coleonyx variegatus. Anim. Behav. 22:684-687.
Klauber, L. M. 1945. The geckos of the genus Coleonyx with description of new subspecies. Tran. San Diego Soc. Nat. Hist. 10:133-216.
Mayhew, W. W. 1968. The biology of desert amphibians and reptiles. Pages 195-356 in G. W. Brown, Jr., ed. Desert Biology, Vol. 1. Academic Press, New York. 638pp.
Miller, A. H., and R. C. Stebbins. 1964. The lives of desert animals in Joshua Tree National Monument. Univ. California Press, Berkeley. 452pp.
Parker, W. S. 1972. Aspects of the ecology of a Sonoran desert population of the western banded gecko, Coleonyx variegatus (Sauria, Eublepharinae). Am. Midl. Nat. 88:209-220.
Parker, W. S., and E. R. Pianka. 1974. Further ecological observations on the western banded gecko, Coleonyx variegatus. Copeia 1974:528-531.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill, New York. 536pp.
Stebbins, R. C. 1972. California amphibians and reptiles. Univ. California Press, Berkeley. 152pp.
Stebbins, R. C. 1985. A field guide to western reptiles and amphibians. 2nd ed., revised. Houghton Mifflin, Boston. 336pp.

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Sidewinder (Crotalus cerastes)

Sidewinder

General Distribution

The sidewinder is widely distributed and locally abundant in the Colorado and Mojave deserts and north just into the southern Great Basin. It is found from sea level to 1800 m (6000 ft) in a wide variety of desert habitats, including woodlands, shrub types, barren areas, and dunes. It is most abundant in desert washes and flats with shrub cover and wind-blown sand, especially at the bases of bushes where the snakes often wait, partially buried. This snake is active from mid-spring to early fall, but activity may be restricted during the hottest part of the summer (Cowles 1945, Klauber 1944, 1972, Lowe and Norris 1950, Stebbins 1954).

Habitat Requirements

This snake has a set of behavioral and morphological specializations for living in sand. It normally buries itself in a coil in fine sand at the base of a bush, if available, or in the open. It may occasionally use mammal burrows or surface cover objects.

Reproduction

Copulation occurs shortly after emergence in April and May and the young are born in mid-summer. Litters average 11 young and range from 7-13 (Stebbins 1954, Klauber 1972).

Daily/Seasonal Activity

This snake is primarily nocturnal, but in the early spring it is active at dusk and even occasionally during the day. It is active from early to mid-spring until late summer or early fall. Populations of southerly or warmer areas become active earlier. It sometimes ceases activity in mid-summer, when temperatures are highest (Stebbins 1954, Klauber 1972). Not known to migrate.

Diet and Foraging

This snake eats small mammals (Dipodomys, Perognathus, etc.), lizards (Cnemidophorus, Uta, Uma, Phrynosoma, etc.) and occasionally birds (Stebbins 1954, Klauber 1972). It is an active forager, but it also waits under bushes for prey, partially buried in sand.

Territoriality/Home Range

Males may be territorial but evidence is not clear (Lowe and Norris 1950).

Predator-Prey Relations

This snake is eaten by kingsnakes and roadrunners, and probably by most avian and mammalian desert predators.

Literature Cited

Cowles, R. B. 1945. Some of the activities of the sidewinder. Copeia 1945:220-222.
Klauber L. M. 1944. The sidewinder, Crotalus cerastes, with description of a new subspecies. Trans. San Diego Soc. Nat. Hist. 10:91-126.
Klauber, L. M. 1972. Rattlesnakes: their habits, life histories, and influence on mankind. 2nd ed. Univ. California Press, Berkeley. 1533pp.
Lowe, C. H., and K. S. Norris. 1950. Aggressive behavior in male sidewinders, Crotalus cerastes, with a Discussion of aggressive behavior and territoriality in snakes. Chicago Acad. Sci. Nat. Hist. Misc. Publ. 66:1-13.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill, New York. 536pp.

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Desert Iguana (Dipsosaurus dorsalis)

Desert Iguana (Dipsosaurus dorsalis)


General Distribution

The desert iguana is widely distributed throughout the Mojave and Colorado deserts below 1000 m (3300 ft) elevation (Stebbins 1954). Its range in California broadly overlaps that of creosote scrub. Desert scrub, wash and succulent shrub habitats are used, as is alkalai scrub. It is found in greatest abundance in sandy creosote flats but can also be found in rocky or hilly areas (Norris 1953, Stebbins 1954).

Habitat Requirements

The desert iguana uses burrows extensively and also climbs into shrubs for shelter from temperature extremes, solar radiation and predators. Mammal burrows are modified or new burrows are constructed by the lizards. Burrows may consist of a shallow, short tube or a more complex arrangement with a central chamber and several exits. The central chamber may measure up to 15 cm in diameter and lie 3-5 cm deep in the soil. When the lizard is present the entrance is usually blocked by sand. This could serve to discourage predators and retard heat gain or loss. These burrows are usually constructed in the hummocks of sand that accumulate around the bases of bushes (usually creosote). Burrows may also serve as nest sites for females. The presence of sand hummocks seems to be important as a construction site for burrows (Norris 1953).

Reproduction

Courtship and copulation occur shortly after emergence in the spring (Norris 1953, Moberly 1961, Mayhew 1971). Egg-laying usually takes place in late May and the young appear in late July to late August. There is considerable variation in these events from year to year and north to south in the range. There is strong evidence that only one clutch of eggs is laid each year (Norris 1953, Mayhew 1971, Grestle and Callard 1972) ranging from 3-8 eggs. Adults reduce surface activity after the appearance of the young; this may reduce competition for scarce food resources. During the period of courtship pairs of lizards (presumably male and female) have been reported foraging together (Norris 1953). This suggests the presence of pair-bonds.

Daily/Seasonal Activity

This species is more heat-tolerant than any other North American reptile. It emerges later in the year and later in the day than other lizards and remains active longer into the hottest part of the day than other lizards. In Palm Springs, it becomes active in late March to mid-April (depending upon the year), later further north (Norris 1953, Stebbins 1954, Moberly 1961, Mayhew 1971). Adults remain active until mid-summer when the young hatch. Young remain active until fall. This species emerges later in the day and remains active later than other species of lizards. Body temperatures of 45° C have been recorded, well above lethal levels for most other species (Norris 1953). Activity consists largely of foraging, moving from one food plant to the next and eating. Most of the time on the surface is spent basking in the sun on hummocks near burrows or in bushes.

Diet and Foraging

These lizards are primarily herbivorous, eating flowers, buds, fruits and leaves of many annuals and perennials, especially creosote. Individuals have been observed to climb up to 2 m (6.6 ft) into a bush to forage. In addition to vegetation, insects, feces (mammal and lizard) and carrion have been reported in their diets (Norris 1953, Stebbins 1954).

Territoriality/Home Range

One study reports male home ranges of .15 ha (.36 ac) and female ranges of .16 ha (.38 ac) (Krekorian 1976). Evidence suggests that this species is territorial during the mating season. During the remainder of the active season, home ranges overlap extensively, and there is little aggressive behavior (Norris 1953, Krekorian 1976).

Predator-Prey Relations

Few reports of predation on this species are available, but it must certainly be preyed upon by Masticophis flagellum and Crotalus cerastes (both lizard-eating snakes), probably by loggerhead shrikes and other avian predators. Young are probably eaten by leopard and collared lizards and mammalian predators (coyote, kit fox, badger, etc.).

Literature Cited

Carpenter, C. C. 1961. Patterns of social behavior in the desert iguana, Dipsosaurus dorsalis. Copeia 1961:396-405.
Grestle, J., and I. Callard. 1972. Reproduction and estrogen-induced vitellogenesis in Dipsosaurus dorsalis. J. Comp. Biochem. Physiol. 42A:791-801.
Krekorian, C. O. 1976. Home-range size and overlap and their relationship to food abundance in the desert iguana, Dipsosaurus dorsalis. Herpetologica 32:405-412.
Mayhew, W. W. 1971. Reproduction in the desert lizard, Dipsosaurus dorsalis. Herpetologica 27:57-77.
Moberly, W. 1961. Hibernation in the desert iguana, Dipsosaurus dorsalis. Physiol. Zool. 36:152-160.
Muth, A. 1977. Eggs and hatchlings of captive Dipsosaurus dorsalis. Copeia 1977:189- 190.
Norris, K. S. 1953. The ecology of the desert iguana Dipsosaurus dorsalis. Ecology 34:263-287.
Pianka, E. R. 1971. Comparative ecology of two lizards. Copeia 1971:129-138.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill, New York. 536pp.

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Field Guide to Reptiles of Southern California Alligator Lizard

Southern Alligator Lizard (Elgaria multicarinata)


General Distribution

Generally common in suitable habitats, the southern alligator lizard is widespread in northern and central California west of the Sierra-Cascade crest and in southern California west of the desert regions. Apparently absent from the extreme northwestern part of the state and from the southern San Joaquin Valley, isolated populations are known from western Inyo Co. and a desert extension of the range occurs along the Mojave River. Populations are also known from most of the Channel Islands. Elevation sea level to 2250 m (7500 ft). Occurs most commonly in valley-foothill habitat types, mixed chaparral, and in open areas of mixed conifer forest.

Habitat Requirements

Cover is provided by surface objects such as rocks, logs, dense vegetation, and human debris. Refuge may also be taken in crevices and rock fissures. Individuals occasionally burrow in loose soil around or under surface objects such as flat rocks. This species sometimes climbs in dense, shrubby vegetation. This species occurs most commonly in open canopy stages of suitable habitats.

Reproduction

Little is known about specific habitat requirements for courtship, mating, and egg-laying in this lizard. Nussbaum et al. (1983) reports that eggs are deposited in “burrows or in stable talus.” Eggs are reported by Shaw (1943) to have been laid in the burrow of a pocket gopher.In southern California, the first clutch of eggs is laid early in June and hatches in about 11 weeks (Goldberg 1972). Two or even three clutches eggs may be laid by females during a single season (Burrage 1965). Clutch size is about 12 with larger females laying more, larger eggs than small females (Goldberg 1972).

Daily/Seasonal Activity

Basically diurnal, this species is active at cooler temperatures than most other lizards with which it coexists. Active southern alligator lizards have been found by Brattstrom (1965) with body temperatures as low as 11° C (52° F). They are active earlier and later in the day than most lizards, sometimes venturing onto warm roads at night. Activity is reduced during the hot periods of summer. In cooler areas a period of winter inactivity occurs but elsewhere individuals may be active all winter long.

Diet and Foraging

Alligator lizards take mostly insects and other arthropods as prey but will take larger food items, especially other lizards (Cunningham 1956). Evidence for their voracious feeding habits is provided by King (1931) who observed a captive adult female consume 20 immature grasshoppers, 11 katydids, 7 shield bugs and stink bugs, and 3 spiders at a single feeding. Cannibalism has been reported.

Territoriality/Home Range

No information is available regarding the nature of the home range. No evidence for the territorial defense of resources has been reported.

Predator-Prey Relations

Racers, rattlesnakes, garter snakes, loggerhead shrikes, red-tailed hawks, and domestic cats have been reported among the predators of alligator lizards. Competition with other lizards for food, space, or othe resources is probably minimized by the unique physiological tolerances of this species, which allow them to be active at different times and to utilize different microhabitats than other lizards. Competition may be further reduced because of the large range of prey size available to alligator lizards.

Literature Cited

Brattstrom, B. H. 1965. Body temperatures of reptiles. Am. Midl. Nat. 73:376-422.
Burrage, B. R. 1965. Notes on the eggs and young of the lizards gerrhonotus multicarinatus webbi and g. m. nanus. Copeia 1965:512.
Cunningham, J. D. 1956. Food habits of the san diego alligator lizard. Herpetologica 12:225-230.
Dawson, W. R., and J. R. Templeton. 1966. Physiological responses to temperature in the alligator lizard, gerrhonotus multicarinatus. Ecology 47:759-765.
Goldberg, S. R. 1972. Reproduction in the southern alligator lizard gerrhonotus multicarinatus. Herpetologica 28:267:273.
King, F. W. 1931. Food habits of alligator lizards. Yosemite Nat. Notes 10:76.
Nussbaum, R. A., E. D. Brodie, Jr., and R. M. Storm. 1983. Amphibians and reptiles of the Pacific Northwest. Univ. Press of Idaho. 332pp.
Shaw, C. E. 1943. Hatching of the eggs of the san diego alligator lizard. Copeia 1943:194.

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Field Guide to Reptiles of Southern California

Banded Rock Lizard (Petrosaurus mearnsi)

General Distribution

The banded rock lizard is restricted to the eastern slopes, canyons and rock-dominated desert flats of eastern San Diego and central Riverside cos., ranging up to 1050 m (3500 ft). It is most common in desert wash, palm oasis, and barren habitats. It prefers rock outcrops, boulder piles and canyon walls and is rarely found on the ground. No information is available on abundance, but it is possible to see several individuals in an area of less than 0.25 ha (0.63 ac) near Palm Springs. This species is active from mid-March until late summer (Stebbins 1954, Hain 1965, MacKay 1972).

Habitat Requirements

This lizard lives almost exclusively on rock outcrops, boulder piles and canyon walls where it takes shelter under rocks, in cracks and crevices (Stebbins 1954, Hain 1965). This species occupies arid and semiarid habitats in the foothills and canyons along the western margin of the Colorado Desert. It is most frequently encountered in habitats dominated by rocks and canyon walls. This lizard moves about on the vertical and under surfaces of rocks, foraging with great agility.

Reproduction

Courtship begins shortly after emergence in early spring. Eggs are laid in June and July. Clutches range from 2-5 and average 3 eggs (Stebbins 1954, Hain 1965).

Daily/Seasonal Activity

These are diurnal lizards that shuttle between sun and shade and are active all day even in hot weather. They usually become active by mid-March and remain active until the end of summer. In some years, late summer rains result in a period of fall activity (Stebbins 1954, Hain 1965, MacKay 1972). These lizards are not known to migrate.

Diet and Foraging

This lizard eats beetles, ants, bees, hemipterans, homopterans, flies, spiders and the buds of some plants (Stebbins 1954).

Territoriality/Home Range

Home ranges were 85 m2 (930 ft2) for males and 40 m2 (440 ft2) for females in Deep Canyon, Riverside Co. (Carpenter 1962, Hain 1965, MacKay 1972, 1975). Male banded rock lizards defend territories but tolerate subadult males; females defend territories against other females (Carpenter 1962, Hain 1965).

Predator-Prey Relations

Few potential predators could pursue this lizard over the surfaces it normally traverses. The young may be taken by Crotaphytus and avian predators.

Literature Cited

Carpenter, C. C. 1962. A comparison of pattern os display of Urosaurus, Uta and Streptosaurus. Herpetologica 18:145-152.
Hain, M. L. 1965. Ecology of the lizard Uta mearnsi in a desert canyon. Copeia 1965: 78-81.
MacKay, W. P. 1972. Home range behavior of the banded rock lizard, Petrosaurus mearnsi. M. S. Thesis, California State Coll., Fullerton.
MacKay, W. P. 1975. The home range of the banded rock lizard Petrosaurus mearnsi (Iguanidae) Southwest. Nat. 20:113-120.
Stebbins, R. C. 1954. Amphibians and reptiles of western North America. McGraw-Hill, New York. 536pp.

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