Short-horned Lizard

Short-horned Lizard
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Order:	Squamata
Family:	Phrynosomatidae
Genus:	Phrynosoma
Species P. douglasii P. hernandesi

The Short-horned Lizard is a small lizard that occurs in North America. Like other horned lizards, it is often wrongly called the "Horned Toad", but it is not a toad at all. It is a reptile, not an amphibian. It is one of five species of lizards in Canada.

Identifiction

The Greater Short-Horned Lizard is often mistaken for its close relative the Pygmy Short-Horned Lizard which has the same basic body type consisting of small pointed scales around the head and back. When in placed together the two are easily distinguished at full size, the Pygmy Short-Horned being much smaller. The Greater Short-Horned Lizard ranges in size from 2-5 inches (4.5-12.4 centimeters) in length and is a flat-bodied, squat lizard with short spines crowning the head^[1]. They have a snub-nosed profile and short legs. The trunk is fringed by one row of pointed scales, while the belly scales are smooth. The color is gray, yellowish, or reddish-brown, and there are two rows of large dark spots on the back. When threatened or aggressive, their colors become more intense.

Females grow to larger sizes than males: females average some 7 cm (about 2.75 inches) from snout to vent (with a maximum total length of about 15 cm) and weigh about 18 g, whereas males have an SVL of only about 5 cm and weigh on the average about 10 g.

Behavior

Short-horned Lizards are "sit-and-wait" predators. They feed primarily on ants, but will also take an occasional grasshopper or beetle. Often, they can be found sitting in the vicinity of ant nests or trails. They are diurnal creatures being most active during midday and burrow at night. They rely extensively on camouflage to avoid predators. If provoked, some of the Short-Horned Lizards can build up blood pressure in regions behind their eyes and accurately squirt their blood at attacking predators which will deter most organisms from continuing their attack.^[2]

Reproduction

The mating season for this species is in spring (May to June). They are viviparous, meaning they give birth to live young: the female will birth 5 to 48 offspring from July to September.^[1] The young will measure about 24 mm from snout to vent and weigh each about one gram. The young have no horns yet and are able to take care of themselves within a few hours; they are not able to fully crawl until they are 1 day old. Males will become sexually active after their first year of life and females generally take two years before they can start reproducing.

Distribution

Short Horned Lizard Phrynosoma Douglassi

The Short-horned Lizard is the most widely distributed lizard in North America and occurs in the widest range of habitats: West into the Cascade crest of Oregon and Washington, then reaching East into North and South Dakota and then South into the Texas panhandle. This species of lizard is mostly an arid mountain dweller living in the range of 900-11,300 feet (170-3440 m).^[1]

Habitat

The Greater Short-Horned Lizard occupies ranges from semiarid plains to high elevations in the mountains. This species is frequently found in a wide range of habitats like shortgrass praries, sagebrush deserts and juniper, pine or fir forests. The soil in these habitats can be stony or rocky but usually has fine loose soil or sand present.^[1] The Greater Short-Horned Lizard is more cold tolerant than other species and is able to reach higher elevations and a greater distribution where the temperature is much cooler.

References

1. ^ ^{a b c d} Stebbins, Robert C. "A Field Guide to Western Reptiles and Amphibians." 3rd ed. Peterson Field Guides, 2003
2. ^ National Geographic Society. "Horned Toad (Short Horned Lizards)" 2009. http://animals.nationalgeographic.com/animals/reptiles/horned-toad.html?fs=video.nationalgeographic.com