The greater short-horned lizard (Phrynosoma hernandesi), also commonly known as the mountain short-horned lizard or Hernández's short-horned lizard, is a species of lizard in the family Phrynosomatidae. The species is endemic to western North America. Like other horned lizards, it is often called a "horned toad" or "horny toad", but it is not a toad at all. It is a reptile, not an amphibian. It is one of seven native species of lizards in Canada.
Etymology
The genus Phrynosoma, means toad-bodied. The specific name, hernandesi, honors Francisco Hernández (1514–1587), a Spanish physician who wrote an early account of a horned lizard, which was published in 1615.
Distribution
The greater short-horned lizard is the most widely distributed horned lizard in North America and occurs in the widest range of habitats: West into central Nevada, east into North and South Dakota, north to southern Saskatchewan and Alberta, and then south into eastern New Mexico to central Mexico, with a few pockets in Trans-Pecos Texas. This species of lizard is mostly an arid mountain dweller living in the range of 900–11,300 feet (170–3440 m).
Habitat
The greater short-horned lizard occupies habitats from semiarid plains to high elevations in the mountains. This species is frequently found in a wide range of habitats like shortgrass prairies, 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. It has 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, its colors become more intense.
Females grow to larger sizes than males: females average about 7 cm (about 2.75 inches) SVL, with a maximum total length (including tail) of about 15 cm (about 6 inches), and weigh about ; whereas males have an SVL of only about 5 cm (about 2 inches), and weigh on the average about . The adult male dermatocranial shape resembles that to be expected of a subadult female of the same body size.
Behavior
The greater short-horned lizard is a "sit-and-wait" predator. It feeds primarily on ants, but also takes an occasional grasshopper or beetle. Often, it can be found sitting in the vicinity of a nest or trails. It is a diurnal creature, being most active during the evening and burrowing at night. It relies extensively on camouflage to avoid predators. Horned lizards have been shown to darken their skin when threatened or to regulate temperature.
Defenses
thumb|Showing blood from [[autohaemorrhaging, in Montana]]
Typically, greater short-horned lizards will remain as still as possible when a predator is nearby, attempting to blend in with the environment. However, if provoked, some species of horned lizards can build up blood pressure in regions behind their eyes and accurately squirt their blood at attacking predators, which will deter canids from continuing their attack. It is rare for horned lizards to squirt blood at humans however, reserving this unique defense primarily for canids (i.e. foxes, coyotes, dogs), which have a strong reaction of distaste to the blood.
Reproduction
thumb|Young juvenile
The mating season for P. hernandesi is in spring (May to June). It is viviparous, giving live birth: the female births five to 48 offspring from July to September.