Phrynosoma douglassii
(Short-horned Lizard)

Key Characteristics

Flattened, rounded body

Horns on head and spines on body

Short horns (not longer than
they are wide at the base)

Viviparous (live-bearing)

General Description:
With their flattened and squat bodies, numerous spikes and horns on their heads, Short-horned Lizards are easily recognized as "horny toads" or horned lizards.   In fact, their Latin name Phrynosoma is translated as "toad body".   Short-horned Lizards range in color from pale gray with few markings, to a darker gray, tan, or reddish-brown ground color with two rows of darker blotches.  The ground color will often be similar to the local substrate coloration.  Ventrally, they are white or cream colored and they generally lack dark speckling.  Short-horned Lizards have numerous small horn-like scales on their dorsum and a readily apparent single row of spine-like scales along their sides.  The horns on the head of Short-horned Lizards are, as the common name implies, short, being no longer than they are wide at the base (Nussbaum et al. 1983).  This feature helps distinguish Short-horned Lizards from the other species of horned lizard found in Idaho, the Desert Horned Lizard (Phrynosoma platyrhinos), which has much longer horns.

Short-horned Lizards are small to medium sized lizards depending on the subspecies, (i.e. the Pigmy Short-horned Lizard and the Salt Lake Short-horned Lizard respectively), (Nussbaum et al. 1983).  They may attain sizes of around 66 mm snout-vent length (2.6 in.) and 100 mm total length (3.9 in.), (Storm and Leonard 1995).    

The reproductive characteristics of Short-horned Lizards are another distinguishing feature that separates them from the congenerClick word for definition, the Desert Horned Lizard.  Short-horned Lizards are viviparousClick word for definition, giving birth to anywhere from 3 to 36 young (Stebbins 1985), but the maximum litter size in the Pacific Northwest is 15 (Storm and Leonard 1995).  Desert Horned Lizards on the other hand are oviparousClick word for definition (egg-laying).  Newborn Short-horned Lizards are very small, around 22 mm snout-vent length (Nussbaum et al. 1983) and resemble the adults.

Habitat:
Short-horned Lizards are found in a variety of habitats including open pine forests, pinion-juniper forests, shortgrass prairies and sagebrush desert (Nussbaum et al. 1983).  The substrate can vary, but there is always some loose soil that allows these lizards to shuffle under the surface.  Short-horned Lizards are more cold tolerant than any other Phrynosoma species; they can be found at elevations as high as 9000 feet and their range extends into Canada (Behler and King 1979).

Idaho Distribution:
In Idaho, the Short-horned Lizard can be found predominately in southern Idaho, with historic records in northwestern Idaho as well (Nussbaum et al. 1983).  From southern British Columbia and southern Saskatchewan, south to northern California and northern Mexico.

Diet:
Varies from place to place, but includes ants and other insects, spiders, snails, sowbugs, and other invertebrates.

Ecology:
HibernatesClick word for definition/aestivatesClick word for definition. When inactive, burrows into soil or occupies rodent burrow. In Idaho, adults are active from mid-April to August. Species is more cold tolerant than other horned lizards. Adults and juveniles are active during daylight hours, while young-of-year have bimodal activity patterns. Predators include longnose leopard lizard, Stellars Jay, Northern Shrike, and other birds.

Reproduction:
Mating has been observed in May in southeastern Idaho. Female gives birth to 3-36 young (3-15 in Pacific Northwest), from July to September, depending on range. Individuals become sexually mature in 2 or more years.

Conservation:

Status:

Unprotected nongame species

Global Rank:

G5

State Rank:

S5

Important State References:
Guyer, C. and A.D. Linder. 1985. Thermal ecology and activity patterns of the short-horned lizard (Phrynosoma douglassi) and the sagebrush lizard (Sceloporus graciosus) in southeastern Idaho. Great Basin Natur. 45:607-614.


Species description, key characteristics and original work by John Cossel Jr. © 1997
Species ecological information from Groves et al. ©1997.
Original images provided by Charles R. Peterson, William P. Leonard, and Henry J. Fabian.© 1998
Design and Optimization by Ean Harker©1999, 2000.
DAI layout by Stephen Burton, and Mike Legler © 1999.