San Diego Management & Monitoring Program


Blainville's horned lizard
Phrynosoma blainvillii

Vertebrata
Iguania

Vertebrata Iguania
Kingdom Phylum Subphylum Class Order Suborder Family

Current distribution rangewide

Native to California and occurs along the Pacific coast from the border of Baja California as far north as Santa Cruz, and inland as far north as Shasta County [1]. A very small disjunctive population also occurs in Siskiyou County.


Known Populations in San Diego County

Found in MUs 1, 3, 4, 5, 6, 7, 8, 9, 10, and 11 within the MSPA [2].


List status

SSC [3]


Habitat affinities

Prefer open areas with sandy soil and low vegetation, but are also found in a wide variety of habitats including valley-foothills, conifer, riparian habitats, grasslands, and semiarid mountains [4]. In southern California, Blainville’s horned lizard is commonly found in chaparral habitats with native ant colonies, and areas with loose sandy soils [5]. During periods of inactivity and hibernation, individuals will burrow into loose soil under logs, rocks, mammal burrows, or crevices. Does not require permanent water.


Taxonomy and genetics

Montanucci (2004) concluded in a morphological study, that P. coronatum is in fact four separate species (P. blainvillii, P. cerroense, P. coronatum, and P. wigginsi) [6]. Out of the four species, P. blainvillii is the only species known to occupy California [7].


Seasonal activity

Diurnal species [8]. During spring and fall seasons most activity occurs in the middle of the day, but is restricted to morning and late afternoon activity during hot summer months. Nocturnal activity may occur during weather events of extreme heat. Individuals during fall and winter are inactive in most areas. Seasonal movements or migration has not been reported, and hibernation is found within the normal area of activity [8].


Life history/ reproduction

The reproduction season can vary from year to year depending on local conditions [9]. Females will lay their eggs (6-21) in a nest under the soil or in a burrow during the months from May to June. Eggs hatch from August to September. Females may lay two clutches of eggs per year. Adults are known to live up to 10 years in captivity [10]


Diet and foraging

Forages between shrubs in open areas, generally near ant nests [9]. Primarily feeds on ants, but will also feed on moth larvae, small beetles, wasps, grasshoppers, spiders, and caterpillars [10].


Threats

Habitat destruction from human development and agriculture, and the spread of nonnative Argentine ants which displace the native food source has threatened and eliminated Blainville’s horned lizard from many areas [11]. The lizard was also extensively exploited by the pet trade until commercial collecting was banned in 1981 [12].


Blainville's horned lizard sources