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SHORT-HORNED LIZARD
Phrynosoma douglassii
Family Phrynosomatidae - Horned Lizards
Order Squamata - Lizards and Snakes
Risk Status
Official status
The Short-horned Lizard is on the Provincial
Red List ( CDC=
G5 SX). According to COSEWIC,
it has been designated Extirpated
(X) in May 2000.
Image Credits: sketch in Reptiles
of British Columbia, Gregory and Campbell, 1984.
Historical facts
The last museum specimens of the Short-horned Lizard from British
Columbia were taken in 1910. Other specimens have been observed
in the wild as recently as 1956, but there are no new authenticated
records in this province. It is most likely that the Okanagan population
was isolated from those farther south in the United States, and
is now extirpated.
Distinguishing features
The Pygmy Short-horned Lizard is a squat, flattened lizard whose
back, sides, and upper part of legs are covered with small thorn-like
spines. The back edge of the head bears a fringe of short spines,
and spines are present along the flanks of the belly between the
front and hind legs. Adults reach about 15 cm with the tail just
under a third of the total body length; females are slightly larger
than males. The head is short and almost as broad as long, and the
legs are short.
Males have enlarged post-anal
scutes, and have a broader tail base than females.
Their dorsal
colour is brown, reddish, tan, or grey with 2 rows of dark blotches
on either side of the midline. A single pair of dark blotches exists
on back and sides of the neck, and the belly is pale yellow or whitish.
Distribution
British Columbia
Only two Pygmy Short-horned Lizard specimens have been collected,
both just north of the International border near Osoyoos in 1898.
One individual was captured and then released in 1937 in the Osoyoos
area, but there is no way to verify this record. Despite sightings
over the years, the population that may have been present in Osoyoos
area, is now considered to be extirpated.
They probably lived on the sandy lacustrine
terraces lining the bottom of the Okanagan valley in the vicinity
of Osoyoos Lake but searches for this species in recent years have
failed.
The species was probably never common in British Columbia but
is considered common south of the international border.
North America
In Canada, another species, the Eastern Short-horned Lizard (P.
hernandesi) occurs in southeastern Alberta and southern Saskatchewan,
however the Pygmy Short-horned Lizard only occurred in British Columbia,
and south throughout central and western Washington, south to Oregon,
northern California, Nevada, and east into southern Idaho.
Habitat
The Pygmy Short-horned Lizard is found in a variety of habitats
over its latitudinal range. In the north of its range it is found
in sagebrush and bunchgrass communities, semi-arid short-grass prairie,
and sunny clearings in juniper and pine woodlands. They even exist
at high altitudes (up to 1800 m) where appropriate cover, loose
sandy, and gravel substrate exists, and insect prey is abundant.
They also are cold-tolerant, which accounts for their occurrence
at high elevations and high latitudes. Pygmy Short-horned Lizards
may rely on natural cavities for hibernation.
Their tolerance for cold and existence in alpine areas in the United
States, have earned these squat lizards the nickname of “Snow
Lizards”, because much of their life may be spent in hibernation.
Why is it endangered?
The Pygmy Short-horned Lizard in Canada seems to be a relict population.
The Osoyoos population of the Pygmy Short-horned Lizard was separated
from the closest neighbors to the south by about 100 km. Agricultural,
urban, and industrial expansion in the Okanagan region probably
is responsible for the decline and eventual loss of this species
in British Columbia. Its population here may never have been large,
but the increased development in recent decades certainly minimizes
the chance that viable populations of short-horned lizards could
re-establish themselves.
The main value of the Canadian populations of this species lies
in their scientific interest, their contribution to Canadian biodiversity,
and the ecology of the Okanagan region. The ecology of high latitude
lizards is poorly understood.
Biology
Breeding
Pygmy Short-horned Lizards are live-bearing or viviparous
- an adaptation to cold climates, and have been known to produce
broods from 3 to 15 young. A specimen in the Royal BC Museum collection
appears to have 3 young. They mate in spring, and give birth in
late summer, to early autumn, a gestation period of about three
months. Pygmy Short-horned Lizards are about 25 mm at birth (22
mm snout-vent length).
Males are sexually mature at about 1 year, but this has not been
determined for females. Mark-recapture studies suggest that females
live as long as five years, but the lifespan of males is unknown.
Behaviour
Pygmy Short-horned Lizards are usually solitary and are cold-tolerant.
They are "sit-and-wait" predators rather than active hunters
and are often found in the vicinity of ant nests. They eat a variety
of insects in addition to ants, and are active during the day, but
very difficult to see because of their cryptic colouration (camouflage)
and spines. The fringe of spines on the body serve to obscure the
body outline against a gravel background rather than acting as any
defensive feature. Pygmy Short-horned Lizards also are difficult
to detect because they remain motionless if approached, whereas
other lizards flee and their motion makes them far more visible
to herpetologists (folks who study reptiles and amphibians) and
predators. Typically, horned lizards are active earlier in the morning
and later in the evening than are other lizards, and based on studies
in the USA, we know that they can have variable body temperatures
over the course of a day. They bury themselves in sand or loose
gravel to avoid mid-day heat, and hibernate from October to April.
The defensive tactics of Pygmy Short-horned Lizards consists of
inflating the body and opening the mouth in a threat display. Presumably,
predators are also discouraged by the presence of the spines on
the body and on the back of the head. Pygmy Short-horned Lizards
do not squirt blood from their eyes, as other horned lizards do.
Diet
Pygmy Short-horned Lizards feed on a variety of insects but take
a fair proportion of ants. Females, due to their greater size, tend
to take larger prey items and also a wider size range of prey.
Predators
Shrikes, hawks, skunks, foxes, and coyotes, all may be potential
predators of Pygmy Short-horned Lizards. Pygmy Short-horned Lizards
are slow and fairly easy to catch compared to other lizards, and
rely on their cryptic colouration to avoid detection. Children and
cats, neither of which are deterred by a species' legal status,
and reptile collectors are a threat to this species. Given their
diet of ants and small insects, horned lizards rarely do well in
captivity and should be left in the wild.
Sources for more
information
Related On-line Sites to Visit
Publications
Our Living Legacy, 1993, RBCM
Status Report - COSEWIC, Powell and Russell, 1992
The SOCAP Workshop Summary, The Nature Trust, 1989
Reptiles of BC, RBCM, 1984
Museum Specimens
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by: 
Industry Canada
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