Cnemidophorus tigris
(Western Whiptail)

General Description:
Depending on the individual, Western Whiptails may appear to have a light ground color that is marked by a dark reticulated (network) pattern, or they may appear to have a dark ground color that is marked by numerous light colored spots.  Regardless, there is always a striped pattern that is apparent (even if faded or obscure).  The four stripes are a light tan, gray or cream color and extend dorsolaterally from the base of the head towards the tail.  The stripes are most prominent in juveniles, and they tend to fade posteriorly in adults.  The previously described pattern of contrasting spots and markings extends onto the base of the tail, but the color darkens towards the tip, becoming a solid bluish-gray.  Juveniles have more of a bluish tinge to their tail coloration (although not as vivid as with Western Skinks).   Western Whiptails have fine, granular scales dorsally, and large rectangular scales arranged in 8 rows ventrally.   The lower limbs of these lizards have a distinct scalation, being covered anteriorly with large, smooth scales that contrast with the granular scales elsewhere on the limbs.  In fact, the genus name loosely translated means "bearing armored legs".

Western Whiptails are medium-sized lizards, and can reach lengths comparable to the Longnose Leopard Lizard and the Mojave Black-collared Lizard.  However, due to their long slender body and whip-like tail Western Whiptails are not as massive as the other two species of lizard.   Western Whiptails can attain snout-vent lengths of 112 mm (4.5 in.) and 330 mm (13 in.) in total length (Storm and Leonard 1995).  The long tail of the Western Whiptail can be more than twice the snout-vent length  if it is unbroken (Nussbaum et al. 1983).   There is a fair chance that a Western Whiptail may be encountered with a tail that is regenerating, as they will readily lose their tail to predators and would be captors.

Western Whiptails mate in the spring, laying 1-4 eggs in June or July, which in turn hatch in August (Storm and Leonard 1995).  The juveniles resemble the adults but are more vividly colored (including the tail, which is more blue in coloration).

Habitat:
Western Whiptails are found in desert regions that have moderate to limited amounts of vegetation such as sagebrush or shadscale.  The substrate may range from sand, gravel, hardpan or loess, but regardless of type, burrows seem to be an important component.  Rocks on the other hand, don't seem to be necessary like they are to some other Idaho lizard species.

Idaho Distribution:
Western Whiptails are restricted to the southwestern portion of the state. From Oregon and Idaho, south to southern Baja California and northern Mexico, and from California east to Colorado and Texas.

Diet:
Eats insects, spiders, scorpions, and lizards.  Known to eat Lepidopterans, crickets, grasshoppers, and beetles.

Ecology:
 Hibernates/aestivates. Active from April to September in northern range. Juveniles may be active on warm days in winter in southern range. In Idaho, individuals are active in early spring (mid-April), aestivate during middle part of summer, and are active again during late summer and early fall. When inactive, individuals remain in underground burrows dug by rodents or lizards.   Colorado study determined that adult home range averaged about 0.10-0.13 ha; population density was about 17/ha. In Idaho, heavy predation results from active foraging behavior; tail breakage exceeds 50% in large adults in some populations. Individuals in Idaho are larger than those in more southern areas.

Reproduction:
Female produces 1 clutch/yr in northern range, 2 (perhaps 3) in south (1 clutch in Idaho). Clutch size is smaller in north than in south (average 2.7 in Idaho). Young reach sexual maturity in 20-23 mo in Idaho and Colorado, and probably at end of first year in far southern range.

Conservation:

Status:	Unprotected nongame species
Global Rank:	G5
State Rank:	S4

Important State Reference:
Burkholder, G.L. and J.M. Walker. 1973. Habitat and reproduction of the desert whiptail lizard Cnemidophorus tigris in southwestern Idaho at the northern part of its range. Herpetologica 29:76-83.