|Scientific Name:||Sauromalus hispidus Stejneger, 1891|
Sauromalus ater ssp. hispidus Stejneger, 1891
Hollingsworth (1998) places Sauromalus hispidus as sister to the clade containing S. ater, S. klauberi, and S. slevini. Petren and Case (1997) place S. hispidus as a sister to S. varius in a terminal clade.
|Red List Category & Criteria:||Near Threatened ver 3.1|
|Assessor(s):||Montgomery, C.E. & Mayer, G.C.|
|Reviewer(s):||Grant, T.D. & Hoffmann, M.|
There is no evidence of extreme fluctuations in abundance or recent population declines in this species. The extent of occurrence is roughly 1,200 km² comprised of at least 12 subpopulations fragmented among isolated islands. No current information on total population size is available, but there are likely fewer than 10,000 mature individuals based on suitable habitat and size of known islands of occurrence. The species is therefore listed as Near Threatened as it almost qualifies for listing as Threatened under criteria B1a and C2.
The Spiny Chuckwalla is found on the islands of the northwestern Gulf of California. It is found on Angel de la Guarda Island, Granito, Mejía, Pond, San Lorenzo Norte, San Lorenzo Sur, and numerous islands in Bahía de los Ángeles, including Cabeza de Caballo, La Ventana, Piojo, Flecha, Mitlàn, and Smith, Gulf of California, Mexico. The area in which this species is distributed is approximately 1,200 km². The species occurs at or just above sea level.
Native:Mexico (Baja California)
|Range Map:||Click here to open the map viewer and explore range.|
The species undergoes population fluctuations according to rainfall; densities are low during and following drought years. This species is physiologically well adapted to arid environments and normal drought cycles do not appear to effect long-term population health. There is no current information on the total population size or its trends.
|Current Population Trend:||Unknown|
|Habitat and Ecology:|
This species is diurnal, often returning to the same burrow or rock crevice each night. Juveniles have a preference for rocky areas, while adults utilize hillside burrows (Grismer 2002). The islands inhabited by S. hispidus often receive little rain, and as noted above, population size often varies as a result of the fluctuating food supply. Daily activity is reduced during drier periods which likely reduces water requirements and water loss rates (Smits 1985a,b). S. hispidus shows one of the lowest water loss rates of any vertebrate (Smits 1985a). This species is the most arboreal species in the genus Sauromalus and is often found on tree branches where it climbs to eat the flowering stems. A variety of food items are eaten including, in order of frequency, shrubs, forbs, tree leaves and fruits, cactus flowers and fruits, and grasses (Sylber 1988).
|Use and Trade:||
This species was sought after and eaten by the Indians of Baja California and may have been translocated among islands in the comparatively recent past (Case 1982, 2002). Archaeological evidence suggests that people have been visiting the islands since the late Pleistocene (Bowen 2009). It is still caught for food by local fisherman and the oil derived from it is used in traditional medicine (Grismer 2002). However, there is currently no evidence that the level of human consumption has a negative effect on the population size of this species.
Fluctuations in population numbers are caused by rainfall and the Spiny Chuckwalla suffers in periods of prolonged drought. This lizard is threatened by the international pet trade and from disease transmission, though it is uncertain if these threats have a negative effect on the population size.
This species occurs on Angel de la Guarda Island which is uninhabited and is a biological reserve. The other islands on which this lizard can be found are also protected as part of the Área de Protección de Flora y Fauna Islas del Gulfo de California. The region is part of the global network of UNESCO Biosphere Reserves. Further research into threats and ongoing monitoring is required.
|Citation:||Montgomery, C.E. & Mayer, G.C. 2010. Sauromalus hispidus. The IUCN Red List of Threatened Species 2010: e.T174482A7078617.Downloaded on 15 October 2018.|
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