Black-tailed Bush Lizard

Black-tailed Bush Lizard, Urosaurus nigricaudus

The Black-tailed Bush Lizard, Urosaurus nigricaudus, is is a member of the Phrynosomatidae Family, which includes Zebra-Tailed, Earless, Fringe-Toed, Spiny, Tree, Side-Blotched and Horned Lizards. It Mexico they are known as lagartija-arbolera cola negra. The Black-Tailed Bush Lizard is small and has a long thin tail that is gray, brown or sooty in color with dark blotches or crossbars on the back, sometimes edged with light coloring or white spots. The tail is usually black, especially in males, that serves to distract predators which can be severed being expendable and it will regenerate. Some have an irregular gray or brown stripe down the middle of the back. The tail, upper sides, and neck are often marked with rust or yellow-brown coloring. The underside is light yellow-gray or white, and some have darker coloring under the tail. Males have a yellow, orange or blue gular fold in the middle of the throat, that when inflated is used as a defense mechanism and also to attract females. They have blue to blue-green patches on the belly, which may connect in the center, and enlarged post anal scales. Females have a yellow, orange, or white throat and no blue on the belly. The Black-Tailed Bush Lizard have small granular scales with a band of enlarged keeled scales down the middle of the back. The scales on the tail are also keeled. They are good climbers and can move quickly from rock to rock. They consume small invertebrates. They are active in spring and summer and hibernated in winter. Males defend their territories and attract females by head-bobbing and push-up displays that expose their throat and ventral colors. Females also do push-up displays. Breeding occurs between April and August with 1 to 2 clutches of 4 to 8 eggs per year. The Black-Tailed Bush Lizard reach a maximum length of 10.6 cm (4.2 inches) to 14.2 cm (5.6 inches) with 3.8 cm (1.5 inches) to 5.1 cm (2.0 inches) from snout to vent. They are most likely confused with Western Side-blotch Lizard, Uta stansburiana elegans (distinctive side blotch). The Black-Tailed Bush Lizards are found in San Diego County and all parts of Baja California. From a conservation perspective they are deemed to be of Least Concern being abundant with a wide distribution.

Black-tailed Bush Lizard, Urosaurus nigricaudus: Collected within the bush of the greater Los Cabos area, Baja California Sur, March 2013. Total Length: 9.8 cm (3.8 inches); tail 64%. Collection courtesy of Maurico Correa, Los Cabos, Baja California Sur. Identification courtesy of Gary Nafis, who indicates that this is either a female (which don’t have black tails) or a juvenile male.