Sceloporus occidentalis
(Western Fence Lizard)
| Key Characteristics |
Large spiny scales dorsally |
|
Blue patches on
the throat and stomach |
General
Description:
Western Fence
Lizards have overlapping, pointed scales
that are the source for the common genus name, the Spiny Lizards. These
"spiny" scales are more pronounced on Western Fence Lizards than
they are on Sagebrush Lizards. Western Fence Lizards have these spiny
scales on their backs and limbs, even on the posterior of their legs, which
is not the case with Sagebrush Lizards the other Sceloporus species
(they have granular scales on the posterior of their thighs), (Nussbaum et
al. 1983). Western Fence Lizards can have a range of dorsal ground coloration
that is usually some shade of gray,
tan or brown. These lizards can lighten or darken the ground color to
some degree, and some individuals are black. The ground color is broken
by a series of wavy dark transverse lines or blotches. These blotches
are more obvious on light colored lizards (females and juveniles are usually
a lighter color than males). Male Western Fence Lizards vary in coloration
from females and juveniles in another ways as well; they have more
distinct belly patches and a throat patch, which are usually bordered
by black markings, and they have scattered
blue or green scales dorsally (Storm and Leonard 1995). Females
and juveniles lack the throat patch and the belly
patches are either less prominent or absent. The posterior
of the limbs are colored orange or yellow with black lines. This
coloration helps distinguish Western Fence Lizards from Sagebrush Lizards
because the later lack the orange-yellow color on the posterior of the limbs.
Western Fence Lizards are medium-sized lizards that are larger than their Idaho congener the Sagebrush Lizard. Western Fence Lizards can attain sizes of around 99 mm snout-vent length (3.9 in.) and 213 mm (8.4 in.) total length (Storm and Leonard 1995). The total length is comprised of a tail that is approximately 1.5 times the snout-vent length (Nussbaum et al. 1983), unless of course the tail is regenerating, as these lizards will readily lose their tail.
Western Fence Lizards mate in the spring laying 3-17 eggs (usually 8) between June and July, which hatch in August (Nussbaum et al. 1983). Juveniles are similar in appearance to adult females.
Habitat:
Western Fence
Lizards occupy a variety of habitats that usually have a vertical component,
and they avoid dense, moist forests and low flat desert valleys (Nussbaum
et al. 1983). In western Idaho, they are usually found in association
with rock outcroppings, talus slopes and cliff faces, they can however also
be found in open forested areas on rocks, logs and trees.
Idaho
Distribution:
Western Fence Lizard are
distributed in Idaho across the lower, western half of the state. From
central Idaho, south through Nevada, and west to Pacific Coast.
Diet:
Eats beetles, flies, caterpillars,
ants, other insects, and spiders.
Ecology:
Hibernates
/aestivates.
Inactive during cold weather. Duration of inactive period varies with local
climate. Emerges from hibernacula
in late winter or early spring (in Northwest, length of activity varies greatly
according to local climatic conditions, but is generally from February to
October). Adult males defend home range during breeding season (in California,
seasonal home range is generally much less than 0.01 ha). Predators include
raptors, snakes, and shrews.
Reproduction:
Female lays eggs from April or May
to June or July. Clutch size varies from 3-17 eggs; largest females produce
largest clutches. Female may produce more than 1 clutch/yr in some areas (in
Northwest, females are thought to lay single clutch). Eggs hatch in about
2 mo. Adults first breed in spring of second year.
Conservation:
|
Status: |
Unprotected nongame species |
|
Global Rank: |
|
|
State Rank: |
S4 |
Important State References:
Diller, L.V. and D.R. Johnson.
1982. Ecology of reptiles in the Snake River Birds of Prey Area. USDI Bur. Land
Manage. Snake River Birds of Prey Research Project, Boise. 107pp.