Great short-horned lizard (Phrynosoma hermandesi) – Estes Park Trail-Gazette

This lizard has a larger range than any other lizard in North America, living in dry habitats ranging from prairie grasslands to pine and fir forests, including rocky and sandy soils. In Colorado, these lizards are found everywhere except the high central mountain range and far eastern prairies.

The body is broad and flattened, unlike many other lizards which tend to have a rather long and narrow body shape. Females are larger than males, reaching 6″ in total length, and give birth to live young, sometimes producing over 45 offspring. The tiny, inch-long juveniles are evenly colored, matching the sandy ground for effective camouflage. The young feed after hatching. Short-horned lizards primarily eat ants, but also other insects and arthropods, normally waiting for prey to approach before the lizard strikes.

This species is characterized by short spines extending from the head on each side and a row of white spines lining the sides of the body. The back has two rows of darker brown spots. The coloration is variable, ranging from a dull, uniformly sandy color to dark blotches, rows of shiny white spines along the side, rusty bands, and orange to pink mouth and head spines, with variegated patterns of dark and white spots. Males exhibit an enlarged area at the base of the tail. Although the lizard is cold tolerant and can be found in the mountains up to 9,000 feet, it hibernates during the coldest winter months, retreating to its burrows in October and emerging again in April.

Short-horned lizards have several defenses against their many potential predators, such as hawks and crows, medium-sized mammals, snakes, and others. The spiny and leathery body surface prevents easy swallowing by birds or snakes. Their detachable tail allows for escape if a predator latches on to the tail first. Additionally, effective camouflage coloring and a habit of remaining very still when they spot a possible predator make them nearly invisible in forest litter. And their ability to squirt blood out of the corner of their eye is an alarming annoyance to an attacking predator.

Population declines in recent decades are likely due to conversion of natural habitat to other uses and loss of prey following ant eradication measures. While many reptiles are fairly long-lived, greater short-horned lizards are believed to live only three to five years in the wild, likely due to their susceptibility to predation by the variety of animals able to easily capture them.

Photos taken with Nikon P900 camera.

James Taulman is a semi-retired wildlife biologist who travels to observe wildlife in New Mexico and the Southwest.

Jack C. Nugent