Pacific Fence Lizards

Text: Amber Loverock

Scientific Name: Sceloporus occidentalis occidentalis

Physical Description: Pacific Fence Lizards can grow to a maximum size of approximately 3-4 inches, with a female’s average size being somewhat larger than its male counterpart. These lizards possess gray-brown coloration with a series of triangular or crescent shaped patches of scales on their backs. Scales are large and spiny. A black band usually borders large blue patches on either side of the organism’s belly. The lower surfaces of the limbs are yellowish with the deepest color occurring on the lizard’s thighs. The underside of the throat is usually white with gray, brown, or blue spots.

Life Span: The average life of a Pacific Fence Lizard is relatively short in a natural setting. Up to 80% of the lizard population may die each year. However, these lizards have the potential to life up to five years under optimal conditions.

 

pacific fence lizard

Photos: Esther Iglich : may be used for educational purposes: credit eiglich@mcdaniel.edu

Growth Pattern: There are three phases in Pacific Fence Lizard growth. In the first phase, between emergence from the egg and hibernation, the lizard grows rapidly from its original 10-20 mm body length. This growth is highly variable due to variations in climate. Most enlargement occurs between the first and second hibernations, where a lizard can grow to 35-45 mm, though the rate of growth may be erratic. After the organism’s second hibernation, it becomes sexually mature and development rate drops dramatically.

Hibernation: Fence Lizards hibernate as late as the end of November and terminate in early February. The lizards spend the winter underground or in the interior of decaying logs.

Range: Pacific Fence Lizards can live in a wide range of habitats, spanning across the western coast of North America. They are found as far north as British Columbia and Washington State, where habitats reach the state and provincial borders. In the southern range of the habitat in Southern California, Pacific Fence Lizards are confined to areas near the coast.

Habitat: Pacific Fence Lizards tend to roam around piles of wood or stone, fences, and abandoned gopher holes that afford protection in the presence of danger.

Food: Pacific Fence Lizards are insectivorous. They distinguish their food by the movement of the prey, or by testing it first with their tongue. In captivity, the lizard is often fed 3-6 crickets every 2-3 days. Exceptionally prone to dehydration, these lizards ingest water by extracting dew and precipitation from leaves and other objects with their tongue.

Reproduction: Males and females pair in the early spring for breeding season. Males make bowing movements to show females the bright blue of their ventral surface. Females lay 6-13 eggs over a period of as much as 8 days. The eggs are white and translucent, although after drying they may become opaque.

Movement: Lizards use both legs to facilitate movement. Pacific Fence Lizards have hooked claws at the end of their fore and hind limbs to allow the organism to climb.

Temperature Regulation: Reptiles are largely dependent on external sources of heat to maintain proper average body temperature. They are poikilothermic, which means lizards tolerate some variations in body temperature in response to the temperature changes in the environment. Pacific Fence Lizards bask in the sun for hours at a time to increase their heat intake. To cool, these lizards will crawl under rocks or in holes underground to avoid direct solar radiation. Pacific Fence Lizards may modify their external colors to aid in temperature regulation. They become dark at low temperatures to maximize heat absorption and light at high temperatures to minimize heat absorption.

Regeneration: Regeneration of tails is a well-known faculty of lizards. The fracture of the lizard’s tail occurs near the middle of some tail vertebra. A sphincter muscle closes about the caudal artery when a fracture occurs, preventing blood loss. An incomplete fracture of the tail causes the growth of a new tail almost as though the fracture was complete. Lizards with this condition have forked tails. When a new tail grows, a cartilaginous rod and muscles grow posteriorly. New vertebrae and segmentation is never restored.

Protection Reactions: The Pacific Fence Lizard typically flees from an area where danger is present. The organism will run and hide in either holes or cracks in stone and earth. The lizard may also "freeze" in the presence of a predator in order to remain inconspicuous. The creature’s coloration and markings camouflage the lizard against its natural habitat.

Sources:

Smith, Hobart M. Handbook of Lizards: Lizards of the United States and Canada. Ithica:

Comstock Publishing Co., 1946.

www.dfg.ca.gov/whdab/cwhr/R022.html