Phrynosoma douglasii

Pygmy Short-Horned Lizard

The pygmy short-horned lizard, scientifically classified as Phrynosoma douglasii, is a small reptile belonging to the family Phrynosomatidae. This species is native to the northwestern United States and adjacent southwestern Canada. It is often colloquially known as a "horned toad" or "horny toad," but it is important to note that despite its common name, it is a reptile and not an amphibian like a toad.

Identification and Physical Characteristics

Distinguishing the pygmy short-horned lizard from its close relative, the greater short-horned lizard (P. hernandesi), can be challenging due to similar physiology, including a squat body and small, pointed scales on the head and body. However, the pygmy species is considerably smaller when mature. The lizard typically measures between 1.25 to 2.5 inches (3.2 to 6.4 cm) from snout to vent. It possesses a flat body, short legs, and a distinctive "snub-nosed" profile. The trunk is bordered by a single row of pointed scales, while the scales on its belly are smooth. Its coloration varies from greyish-beige to yellowish or reddish-brown, often influenced by the season and geographic region. Two rows of prominent dark spots adorn its back. When the lizard is preparing to mate, feels threatened, or is reacting defensively, its colors become more intense, a phenomenon sometimes referred to as "fired-up."

Behavior and Diet

The diet of the pygmy short-horned lizard is adaptable, changing based on regional availability, the season, and the individual's age and sex. Neonates and hatchlings show a strong preference for ants, which constitute approximately 89% of their diet. As they mature, their consumption of ants decreases, making up around 72% of their diet, and they begin to supplement with various arachnids, beetles, grubs, isopods, terrestrial mollusks like snails and slugs, earthworms, and Lepidopterans along with their caterpillars. They may also consume plant matter. Throughout their lives, ants remain a consistent part of their diet, though the total quantity of any specific prey species fluctuates seasonally.

Habitat and Adaptations

Within its family, the pygmy short-horned lizard is recognized for its remarkable ability to tolerate lower temperatures compared to many of its relatives. This adaptation allows it to inhabit biomes that might otherwise be inaccessible to similar species, particularly those that experience freezing winters. This resilience to cold is a key factor in its survival and distribution.

Predators and Threats

This small lizard faces a number of natural predators, including the long-nosed leopard lizard, Stellar's jay, northern shrikes, coyotes, foxes, various birds of prey, bobcats, and potentially larger snakes capable of consuming squamates, such as kingsnakes. Specific threats to its population are not detailed in available records.

Taxonomy and Etymology

Previously, the greater short-horned lizard was considered the same species as the pygmy short-horned lizard. However, recent mitochondrial DNA evidence has led to their classification as distinct species, with the pygmy species primarily found in the northwestern United States and formerly in parts of southwestern Canada, where it is now extirpated. The specific name, douglasii, was given in honor of the Scottish botanist David Douglas.