Common Name
Island Night Lizard

Scientific Name
Xantusia riversiana

Conservation Status
Listed as threatened in 1977, the night lizard population has rebounded since then.

Habitat
The island night lizard prefers boxthorn, prickly pear cactus, and cracks and crevices in and around rock outcrops and surface boulders.

Additional Information
Island night lizards (Xantusia riversiana) are an endemic Channel Islands reptile, known only to occur on Santa Barbara Island in the park and on San Nicolas and San Clemente Islands. They are the most morphologically distinct of the endemic vertebrates on the Channel Islands, indicating they have been isolated from the mainland for a long time. The best habitats for the lizards are boxthorn (Lycium californicum), prickly pear cactus (Opuntia oricola and O. littoralis), and cracks and crevices in and around rock outcrops and surface boulders. These areas provide protection from predators. They are also often found under rocks, driftwood, and fallen branches. Suitable habitat on Santa Barbara is in all of the canyons and on some of the sea cliffs, especially on the south side of Signal Peak. Island night lizards are very sedentary and have very small home ranges, averaging about 183 square feet (17 square meters). They are most active at midday. The lizards breed in April, with young being born in September.

Fellers and Drost found densities of 1,300 lizards per acre in boxthorn and 1,000 lizards per acre in prickly pear. This high density is probably due to a combination of factors, including the lizard’s low metabolism, diverse diet, sedentary nature, and small, overlapping home ranges.

Although abundant in their favored habitats, island night lizards are still sensitive to disturbance. Individual lizards can be trampled and habitat damaged by people walking off trail.

On August 11, 1977, the U.S. Fish and Wildlife Service listed the island night lizard as a threatened species because of its restricted range and apparently low population levels on Santa Barbara and San Nicolas islands. Their populations were thought to have been reduced due to past farming and grazing, fire, and the introduction of nonnative animals and plants. However, Feller and Drost estimated that the total population on Santa Barbara was at least 17,600, and concluded that the population was not threatened with extinction as was previously thought.