Uta
stansburiana
(Side-blotched Lizard)
Key Characteristics |
Gular fold |
Dark blotch behind forelimbs |
General
Description:
Side-blotched
Lizards are petite lizards that are covered with fine granular scales with the
exception of the tail, which has scales that are slightly keeled. Two
other morphological characteristics of this species are the gular fold on the
throat and the large interparietal scale on the top of the head. The third
eye (the parietal eye)
is easily located in the center of this scale. The dorsal ground color
of Side-blotched Lizards is generally a light shade of gray or tan that is sprinkled
with both light and dark colored spots. Some of these spots may be light
blue on both sexes, and males often have orange sides and neck, particularly
during the breeding season. The ventral coloration of Side-blotched Lizards
is more subdued, being a light cream or white. The most obvious marking
is the namesake of these lizards, and is the dark
bluish-black spot that is present on the sides behind the forelimbs.
These spots are more distinct in males, but females and juveniles generally
have the marking to some degree. Overall, females
and juveniles are less vividly colored than their male counterparts.
Side-blotched Lizards are the smallest lizard species in Idaho. Adults only attain snout-vent length sizes of around 54 mm (2 in.) and total lengths of 130 mm (5 in.), (Storm and Leonard 1995) with their tails being up to 1.5 times their snout-vent length (Nussbaum et al. 1983).
Side-blotched Lizards mature early and may lay two clutches of eggs during one breeding season (up to three clutches in some parts of their range) (Behler and King 1979, Nussbaum et al. 1983). The clutches usually contain 2-5 eggs, which are laid during late April or May. The eggs hatch in about two months (Storm and Leonard 1995). Juveniles look like adult females (except that neonates seem to have large heads for their body size).
Habitat:
Side-blotched
Lizards inhabit arid to semi-arid
regions that are vegetated with desert shrubs or pinion-juniper trees (Nussbaum
et al. 1983). These lizards can be found on a variety of substrates such
as sand, gravel or loess and there may often be a rock
component to the area. In Idaho, Side-blotched Lizards often share
the same rocky habitats with Western Fence Lizards.
Idaho
Distribution:
Side-blotched
Lizards in Idaho are found across the southwestern portion of the state.
From Washington, south to tip of Baja California
and northern Mexico, and east to western Colorado and Texas.
Diet:
Eats insects (frequently Hymenoptera,
Coleoptera, Hemiptera, Orthoptera), spiders, scorpions, mites, and ticks. Adult
males sometimes cannabalize young. In Idaho, diet may include flies, ants, and
caterpillars.
Ecology:
Hibernates/aestivates.
Active from March to November in northern range; active all year in southern
range. May aggregate during hibernation in some areas. In Idaho, species is
strictly diurnal; may be active during morning and evening during hot, summer
months. In Colorado study, home range size was estimated at 0.01-0.03 ha, and
population density was estimated at 25-44 adults/ha. Density ranged from 11-285
individuals/ha in 7 sites in California, Nevada, Oregon, and Washington (mean
density was 60/ha and 78/ha, in 2 consecutive years). Most abundant lizard in
Idaho; predators include night snakes, striped whipsnakes, and raptors.
Reproduction:
Breeding season lasts longer in southern
range than in north. Female lays 1-2 clutches of 3.75 eggs (Idaho average) in
March-August. Young reach sexual maturity in 1-2 yr.
Conservation:
Status: |
Unprotected nongame species |
Global Rank: |
|
State Rank: |
S5 |
Important State References:
Bakewell, G., J.M. Chopek,
and G.L. Burkholder. 1983. Notes on reproduction of the side-blotched lizard
Uta stansburiana stansburiana in southwest Idaho. Great Basin Natur. 43:477-482.