Blunt-Nosed Leopard

Tagged: animal, animals, bird, cat, insect, mammal

Gambelia silus
( images )

The decline of this attractive lizard dates back to the California Gold Rush of 1849, when parts of its habitat were turned over to agriculture to feed the influx of miners. The habitat of the blunt-nosed leopard lizard is now restricted to a number of scattered areas in the San Joaquin Valley in California. The lizards use the deserted burrows of small mammals for shade, shelter, and hibernation in winter. Although they are diurnal (active during the day), leopard lizards tend to shelter during the hottest part of the day. They are often active at air temperatures of up to 104°F (40°C), when the soil temperature is about 122°F (50°C). From September onward the lizards take to their burrows to spend the colder months in a dormant state. Leopard lizards have predators, which is part of the natural balance; but when the lizards are forced into smaller areas by human disturbance, and their vegetation cover is destroyed, they become more exposed and vulnerable to these predators.

The Human Threat

As the human population increased in the San Joaquin Valley, so did agriculture and urban development. This inevitably encroached on the habitat of the blunt-nose leopard lizard. Further damage occurred as industries developed around the extraction of oil and minerals. By 1985 barely 10 percent of the original wild land on the San Joaquin Valley floor had been left undeveloped. The road building and landfill dumping that accompanied development in the valley were also destructive to the lizard’s habitat, and the damage to the delicate balance of the desert ecosystem largely ignored. Lizards and their habitats were destroyed under construction machinery; roads and irrigation ditches fragmented the lizard’s territory. Pesticides sprayed on crops also had a detrimental effect on much of the wildlife. Leopard lizards are insectivorous-a large part of their diet includes insects-so their food supply can be drastically reduced, or contaminated, by the drift from crop spraying. Where the land has been adapted for pastoral farming, grazing animals eat the natural vegetation and trample rodent burrows and lizard egg sites. They also break the soil surface, which can cause soil erosion. The removal of natural vegetation through grazing allows nonnative plants to invade, eliminating, the open spaces preferred by the lizard. The threats to the blunt-nosed leopard lizard from continuing habitat destruction were highlighted as far back as 1954, but the species was not listed as endangered by the United States Department of the Interior until 13 years later. It was given state listing in 1971.

Recovery Plans

The first recovery plan for the species was not prepared until 1980 (revised in 1985). Since then numerous studies have been carried out, including aerial surveys, to determine the amount of suitable territory still existing. Some areas have been purchased as reserves, but lack of funding has prevented this in many areas. Conservation is a complex business needing comprehensive studies of numerous aspects: ecology, population, feeding habits, breeding, and genetic variability. Although much information has now been gathered, the scattered nature of the remaining lizard sites complicates matters because of environmental variation. It may be a long time before all the necessary knowledge is accumulated. The blunt-nosed leopard lizard has proved itself to be adaptable, often colonizing sites that have been disturbed then abandoned. However, unless the decline of its habitat and its continued isolation in ever-shrinking areas are halted, the species may never recover. Its survival depends on further land acquisition and the construction of “corridors” to allow groups to move between fragmented sites, so preventing the genetic problems that develop in small populations. Its habitat must be protected, improved, and managed in such a way that the land is only used in a manner compatible with the lizard’s existence. This is a tall order given the conflicting interests over land use. Recovery of this species will take a very long time; it remains to be seen if it will be successful.The blunt-nosed leopard lizard is active by day and prefers hot, dry, and sparsely vegetated areas. It can run on its hindlegs to escape predators, which include snakes, birds, and mammals.

Statistics

• Family: lguanidae
• World population: Unknown
• Distribution: San Joaquin Valley,California
• Habitat: Arid areas, often alkaline, saline or sandy soils with sparse vegetation, rarely above 2,500 ft (800 m)
• Diet: Mainly insects, other lizards, and small mammals
• Breeding: One clutch of 2-6 eggs laid per year
• Related endangered species: None
• Size: Length: up to 13 in (33 cm)
• Form: Slender lizard with long, “whippy” tail, blunt nose, and spotted throat; variable pattern of dark spots and light bars on yellow, fawn, gray, or dark- brown background; body color lightens with increased temperatures, so spots become indistinct; mated females and juveniles develop orange spots; males have red coloration in the breeding season

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