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Blunt-Nosed Leopard Lizard
Basic Species Information
Endangered. This species is in danger of extinction throughout all or a significant portion of its range.
The blunt-nosed leopard lizard is a relatively large lizard of the Iguanidae family. It has a long, regenerative tail; long, powerful hind limbs; and a short, blunt snout. Adult males are slightly larger than females, ranging in size from about 9 to 12 cm (3.4 to 4.7 inches) in length, excluding tail. Females are about 9 to 11 cm (about 3.4 to 4.4 inches) long. Males weigh about 37 to 43 g (1.3 to 1.5 ounces); and females weigh about 23 to 34 g (0.8 to 1.2 ounces).
Although blunt-nosed leopard lizards are darker than other leopard lizards, they exhibit tremendous variation in color and pattern on their backs. Their background color ranges from yellowish or light gray-brown to dark brown, depending on the surrounding soil color and vegetation. Their undersides are uniformly white. They have rows of dark spots across their backs, alternating with white, cream-colored or yellow bands. The Recovery Plan for Upland Species of the San Joaquin Valley, California provides more details about identification.
The lizards are most active on the surface when air temperatures are between 74° and 104° F, with surface soil temperatures between 72° and 97°. Smaller lizards and young have a wider activity range than the adults.
Blunt-nosed leopard lizards feed primarily on insects (i.e., grasshoppers, crickets and moths) and other lizards.
Leopard lizards use small rodent burrows for shelter from predators and temperature extremes. Burrows are usually abandoned ground squirrel tunnels, or occupied or abandoned kangaroo rat tunnels. Each lizard uses several burrows without preference, but will avoid those occupied by predators or other leopard lizards. In areas of low mammal burrow density, lizards will construct shallow, simple tunnels in earth berms or under rocks.
Males are highly combative in establishing and maintaining territories. Male and female home ranges often overlap. The average home range size varies from 0.25 to 2.7 acres for females and 0.52 to 4.2 acres for males. Density estimates range from 0.1 to 4.2 lizards per acre. Population densities in marginal habitat generally do not exceed 0.2 blunt-nosed leopard lizards per acre. There are no current overall population size estimates for the species.
The blunt-nosed leopard lizards spend the colder months of the year underground in a state of dormancy. They emerge in March or April.
Breeding activity begins within a month of emergence from dormancy and lasts from the end of April to the end of June. Male territories may overlap those of several females, and a given male may mate with several females.
Two to six eggs are laid in June and July, and their numbers are correlated with the size of the female. Under adverse conditions, egg-laying may be delayed one or two months, or reproduction may not occur at all. Females typically produce only one clutch of eggs per year. However, some may produce three or more under favorable environmental conditions.
After about two months of incubation, young hatch from late July through early August, rarely to September. Seasonal above ground activity is correlated with weather conditions, primarily temperature.
This species is found only in the San Joaquin Valley and adjacent foothills, as well as the Carrizo Plain and Cuyama Valley. It inhabits open, sparsely vegetated areas of low relief on the valley floor and the surrounding foothills. It also inhabits alkali playa and valley saltbush scrub. In general, it is absent from areas of steep slope, dense vegetation, or areas subject to seasonal flooding.
Although the boundaries of its original distribution are uncertain, the species probably ranged from Stanislaus County in the north to the Tehachapi Mountains of Kern County in the south, and from the Coast Range mountains, Carrizo Plain and Cuyama Valley in the west to the foothills of the Sierra Nevada in the east.
The currently occupied range consists of scattered parcels of undeveloped land on the Valley floor, most commonly annual grassland and valley sink scrub.
Potential predators are numerous. They include snakes, predatory birds and most carnivorous valley mammals.
Habitat disturbance, destruction and fragmentation continue as the greatest threats to blunt-nosed leopard lizard populations. It was first recognized in 1954, that agricultural conversion of its habitat was causing the extirpation of the blunt-nosed leopard lizard.
Livestock grazing can result in removal of herbaceous vegetation and shrub cover and destruction of rodent burrows used by lizards for shelter. However, light or moderate grazing may be beneficial, unlike cultivation of row crops, which precludes use by leopard lizards.
Direct mortality occurs when animals are killed in their burrows during construction, killed by vehicle traffic, drowned in oil, or fall into excavated areas and are unable to escape.
Displaced lizards may be unable to survive in adjacent habitat if it is already occupied or unsuitable for colonization.
The use of pesticides may directly and indirectly affect blunt-nosed leopard lizards. The insecticide Malathion has been used since 1969 to control the beet leafhopper, and its use may reduce insect prey populations. Fumigants, such as methyl bromide, are used to control ground squirrels. Because leopard lizards often inhabit ground squirrel burrows, they may be inadvertently poisoned. Visit the California Department of Pesticide Regulation Endangered Species Project web page for more information.
Cultivation, petroleum and mineral extraction, pesticide applications, off-road vehicle use, and construction of transportation, communication, and irrigation infrastructures collectively have caused the reduction, fragmentation of populations and decline of blunt-nosed leopard lizards.
WHAT YOU CAN DO
Wherever you live in California, there are zoos and nature centers where you can see and learn about lizards.
Need more specifics? Download the Blunt-Nosed Leopard Lizard scientific species account.
Photo Credit: Rob Conohan
Photos & More
More Information on the Blunt-Nosed Leopard Lizard is available on ECOS.gov
Photo Credit: Thomas Leeman / USFWS
- January 23, 2015 - Maricopa Sun, LLC’s Habitat Conservation Plan Incidental Take Permit Issued
- January 13, 2015 - Public Input Sought on Conservation Plan for New Solar Park in Merced County
- December 08, 2014 - Maricopa Sun Solar Complex in Kern County to be Issued Endangered Species Permit
- September 18, 2014 - Sacramento Fish and Wildlife Office Partners Granted $8M+ for Conservation
- May 27, 2014 - Public Input Sought on Conservation Plan for New Solar Complex
- December 22, 2011 - Service Seeks Public Comment for New Solar Complex
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Last updated: December 20, 2017