Reptiles & Amphibians

The scaly face of a horned lizard stares into the camera.  Scales create pointy brows above its eyes.
Horned lizards' scales are specially shaped to deter predators from eating them.

NPS photo Amanda Murphy


The American Southwest is well-known for the quantity and diversity of the reptiles and amphibians, and El Malpais is no exception. Whether you walk down a trail or bushwack into the backcountry, you never know what you will see scurrying along in a grassy meadow, hiding on the other side of a clinker of a'a lava, or slithering along in a fold a pahoehoe flow.

A mottled-colored bull snake flicks its tongue.
Although not venomous like their rattlesnake look-alikes, bullsnakes should still be given a respectful amount of space.

NPS photo Amanda Murphy


The bullsnake (Pituophis catenifer sayi) is one of the largest snakes native to North America, growing up to 8 feet (2.4 meters) long. Often confused with rattlesnakes, bullsnakes lack a rattle. However, bullsnakes mimic rattlesnakes in coloration and dorsal, or back, pattern. They can also shake its tail and re-create a rattle-like sound with its hiss, further encouraging potential predators to leave it alone.

A small lizard crouches against the ground.

NPS photo Amanda Murphy

Horned Lizard

More commonly referred to as "horned toads" or "horny toads,", horned lizards are fully reptilian. Approximately five different species live in the El Malpais region, but a unifier between them is their method of self-defense. When a horned lizard feels threatened, it can inflate its body to twice their normal size, which makes them much harder to predators to bite or swallow. A few species can shoot a stream of blood from the corner of their eyes when attacked. This method causes enough confusion in predators for the horned lizard to make its escape.

A diamondback rattlesnake coils up and bares its rattle within blades of grass.
Western diamondback rattlesnake venom can be harmful to people and pets, so remember to give them space if you encounter one.

NPS photo Amanda Murphy

Western Diamondback Rattlesnake

An icon of the American southwest, western diamondback rattlesnakes (Crotalus atrox) are one of the venomous species of snake at El Malpais. Diamondbacks will often spend daytime hours coiled in the shade of fallen trees, rocks or low growing shrubs. During summer months, diamondbacks are most active in the mornings and evenings, hunting for rodents.

As their name implies, diamondback rattlesnakes are easily identified by diamond-shaped patterns on its back. Other defining features include a triangle-shaped head, solid black and white striping at base of its tail rattle, and the rattle itself.
If a western diamondback feels threatened, it will first coil up and create an S-shape in its neck. If coiling doesn't work, it will then lift its head and part of its neck above the ground, and begin to rattle its tail. If you hear rattling while on the trail, immediately back away from where you first heard it.

A male collared lizard basks on a rock.
The bright coloration of male collared lizards help them stand out on basalt lava flows.

NPS photo Amanda Murphy

Collared Lizards

Commonly found in rocky areas, collared lizards (Crotaphytus collaris) bask in the sun warming their body and looking for prey. When defending their territory, males are known to bob their heads and do "push-ups." Both male and female collared lizards bear one to three solid black bands around their necks, appearing as solid collars. Males lizards are also brightly colored in yellows and blues, especially during mating season. Female collared lizards are more plainly colored, but gain red or orange bands between the ever-present black collars when preparing to lay eggs.

A prairie rattlesnake coils its neck into an S-shape while in scrubbrush.
Although smaller than a western diamondback rattlesnake, prairie rattlesnakes should be given equal respect.

NPS photo Amanda Murphy

Prairie Rattlesnake

Prairie rattlesnakes (Crotalus viridis) are one of the more timid species of rattlesnake, often evading a confrontation rather than coiling up and rattling. However, they may still rattle if they feel cornered.
Although prairie rattlesnakes are smaller than western diamondback rattlesnakes, prairie rattlesnake coloration is similar with a range of green to brown with a series of brown or black blotches. No black and white striping is present at the base of the rattle. Prairie rattlesnakes are also venomous to people and pets, so if you hear a rattle at any time on your hike, back up and give the snake plenty of space.

Two stacked images:
Top image:  a green and gray canyon treefrog nestles in a crack between rocks.
Bottom image:  a brown and gray canyon treefrog rests in a shallow puddle.
Canyon treefrog coloration can range from a mottled green and white to a spotted gray.

NPS photos Amanda Murphy, Dave Hays

Canyon Treefrog

The canyon treefrog (Hyla arenicolor) is a small, rough-skinned frog with abrasive pads on the toes of all four feet for climbing. Despite the dry climate of the area, the canyon tree frog is a Colorado Plateau and Southwest native. Colors and patterns can vary from individual to individual. A canyon treefrog's tongue is attached to the front of its jaw and actually flips forward to catch insects.

Canyon treefrogs rely on tinajas, temporary pockets of water in bedrock depressions, that fill with summer monsoon rains to lay their eggs. The laid eggs are then in a race against the tinaja evaporating to hatch into tadpoles, mature into froglets, and find a cooler environment as adults.

After mating and the eggs are laid, adult canyon treefrogs quickly leave the tinajas in search of cool, moist cracks in rocks or the underground burrows of other animals to avoid the dry weather that follows the short monsoon season.


Last updated: December 13, 2020

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