U.S. Fish & Wildlife Service

This species list is the result of notes and observations of many people over the course of several years. The list is considered to be incomplete and is intended to offer visitors or interested persons an introduction to the refuge's amphibian and reptile species.

[Toads]  [Frogs]  [Turtles]   [Lizards]  [Snakes]  [About Poisonous Snakes]

Amphibians

Amphibians are described as having moist glandular skin and toes without claws. Their young pass through a larval stage (usually aquatic) before metamorphosing into the adult. Frogs and toads belong to this group.

Toads and frogs are not generally thought of as resident of the desert, but five toad and at least one frog species occur on the Cabeza Prieta NWR. Most, such as the Colorado river toad, are located near artificial water catchments or natural basins that fill with water during summer storms. Others, such as Couch's spadefoot toad, occur throughout the refuge and are very active following summer thunder showers.

Toads

Couch's spadefoot toad (Scaphiopus couchi)
Occurs primarily in the eastern valleys of the refuge. Most noted for the black "spades" on its hind feet that it uses for digging and burrowing.

Great plains toad (Bufo cognatus)
May occur throughout the drainage areas of the refuge, in the eastern valleys.

Sonoran green toad (Bufo retiformis)
Very localized. In the United States occurs only in southern Arizona. On the refuge it is present in the Aqua Dulce Mountains and the lower San Cristobal Wash area.

Colorado River Toad (Bufo alvarius)
Largest native toad in the western U.S., with adults often 20 cm long in length. This toad is common at water tanks and catchments throughout the refuge.

Red-spotted toad (Bufo punctatus)
Most common toad throughout the refuge.

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Frogs

Canyon treefrog (Hyla arenicolor)
Highly localized, present at or near natural permanent water sites.

Other toad and frog species thought to occur on the refuge include: Western Spadefoot Toad (Scaphiopus hammondii); Woodhouse's Toad (Bufo woodhousei australis); and the Burrowing Treefrog (Pternohyla fodiens).

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Reptiles

Reptiles have scales or plates covering their bodies and their toes (when present) have claws. Turtles, lizards, and snakes are in this group.

Turtles

Desert tortoise (gopherus agassizii)
Present in the eastern portions (Pima County) of this refuge. This desert dweller is most active in the spring and following late summer rains. Flowers and new green growth are favorite foods of the tortoise. The tortoise becomes dormant in burrows during the hottest summer and cooler winter months.

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Lizards

Desert banded gecko (Coleonyx variegatus)
This colorful little lizard is present throughout the refuge but is seldom seen as it is nocturnal. The gecko is capable of emiting chirping and squeaking sounds.

Chuckwalla (Sauromalus obesus)
Largest of the lizards on the refuge and is present in all of the mountain ranges. Although extremely wary, the chuckwalla can often be seen sunning itself on top of distant boulders. It is strictly a vegetarian.

Desert iguana (Dipsosaurus dorsalis)
This lizard occurs throughout the refuge often among kangaroo rat dens on creosote bush covered flats. The rat dens provide living quarters and protection while the yellow blossoms of the creosote bush are an important food. When sprinting, this species runs on its hind legs.

Zebra-tailed lizard (Callisaurus draconoides)
A swift moving, colorful lizard with a black and white ringed tail usually seen in the valleys and lower hills throughout the refuge.

Colorado desert fringe-toed lizard (Uma notata)
Highly localized in the sand dune area surrounding the Pinacate lava field. When pursued, this lizard readily runs and buries itself in loose sand.

Collared lizard (Crotaphytus collaris)
This lizard inhabits rocky areas throughout the refuge where it may be seen jumping from rock to rock searching for other lizards and crickets. An aggressive reptile, the collared lizard may attempt to bite if caught.

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Long-nosed leopard lizard (Gambelia wislizenii)
Not common. Present primarily in lowlands and flats across the southern portions of the refuge. Habits similar to C. collaris, feeding mainly on lizards, spiders, and insects.

Desert spiny lizard (Sceloporus magister)
Associated primarily with brushy areas such as mesquite thickets. Very recognizable by its thick, heavy scales. It has a very thick body and is stoutly built.

Long-tailed brush lizard (Urosaurus graciosus)
Present in valleys, associated with mesquite and palo verde stands. Aptly named as its tail is often twice as long as its body length.

Tree lizard (Urosaurus ornatus)
Found in brushy areas throughout the refuge.

Side blotched lizard (Uta stansburiana)
The most common lizard observed everywhere on the refuge, and all months of the year. A warm December or January day will bring out a few of these lizards. It is a relatively small lizard with little dark spots behind its front legs. Males often have small blue dots on their tails and backs.

Desert horned lizard (Phyrnosoma platyrhinos)
Abundant throughout the refuge in valley areas and washes. This member of the lizard family feeds almost exclusively on ants. As a defensive mechanism, these lizards can squirt blood from their eyes sockets.

Regal horned lizard (Phrynosoma solare)
Common to the eastern portion of the refuge (Pima County). Similar to P. platyrhinos except its "horns" are larger and more distinctive.

Great basin whiptail (Cnemidophorus tigris)
A whiptail is recognized by its long, sleek body, pointed nose and very long tail. These lizards are common throughout the refuge and can often be seen during the heat of day searching for termites and other insects.

Sonoran spotted whiptail (Cnemidophorus sonorae)
Present only in the far eastern portions of the refuge. The Little Ajo Mountains seem to be the western edge of their range. A bright blue tail separates these from the other whiptails in the area.

Red-backed whiptail (Cnemidophorus burti xanthonotus)
Found on the refuge in the Agua Dulce Mountains. This subspecies has a limited and spotty distribution. It is found elsewhere in Arizona.

Gila monster (Heloderma suspectum)
The only poisonous lizard in the United States. A large heavy bodied lizard with black and orange, or pink 'bead-like' scales. The gila monster kills its prey by chewing and grinding with powerful jaws that allow its venom to run down grooves on its rear teeth.

Other lizard species thought to occur on the refuge are: Sonoran spiny lizard (Sceloporus clarki); Flat-tailed horned lizard (Phrynosoma m'callii); and the desert night lizard (Xantusia vigilis).

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Snakes

Rosy boa (Lichanura trivirgata)
Observed on rocky bajadas. A heavy bodied snake. Scales are smooth and shiny with a slaty, beige or rosy color.

Spotted leaf-nosed snake (Phyllorhynchus decurtatus)
Lives on valley floors and in washes in the eastern portions of the refuge. The snakes prefer the creosote bush flats where they feed on small lizards.

Saddled leaf-nosed snake (Phyllorhynchus browni)
Closely related to the spotted leaf-nosed snake, this snake occupies the rocky areas of the desert between the valley floor and the mountains. Closely associated with stands of saguaro cactus and palo verde vegetation belts.

Coachwhip or red racer (Masticophis flagellum)
Present all across the refuge in the lower hills and valley floors. It often uses rodent burrows under creosote bushes for hiding. Coachwhips are swift, aggressive, and may attempt to bite if caught.

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Sonoran whipsnake (Masticophis bilineatus)
Occurring primarily in the Pima County portions of the refuge. This species may climb trees, feeding on young birds and small lizards.

Western patch-nosed snake (Salvadora hexalepis)
Found on the lower mountain slopes and valley floors. Medium sized snake (around one meter) with a pronounced triangular patch on nose.

Glossy snake (Arizona elegans)
A noctural resident of the refuge on valley floors and in brushy areas. Looks like faded gopher snake. Brown, cream, pinkish, or yellowish gray in color with gray blotches edged with black.

Gopher snake (Pituophis melanoleucus)
One of the largest snakes on the refuge, often exceeding three meters. When encountered it may flatten its head, vibrate its tail, and hiss loudly, imitating a rattlesnake. Present throughout the refuge.

California kingsnake (Lampropeltis getulus californiae)
Medium-sized snake with smooth scales. Observed on bajadas on the refuge.

Long-nosed snake (Rinocheilus leconti)
A medium-sized, colorful snake that readily burrows into sand or gravel. Commonly seen on the refuge.

Western shovel-nosed snake (Chionactis occipitalis)
A small snake (30.5 cm) that burrows readily through sand and gravel valley floors on the refuge.

Arizona lyre snake (Trimorphodon disutatus lambda subsp.)
A resident primarily of rocky terrain. The lyre snake is mildly venomous; the effect of its venom on humans is not well known. Not considered dangerous.

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Spotted night snake (Hypseglena torquata)
Another mildly venomous snake like the lyre snake. It uses rear grooved teeth to "chew" poison into a bite. Associated primarily with rocky, low hills of the refuge.

Arizona coral snake (Micruroides euryxanthus)
A highly dangerous, poisonous snake that should never be handled. Only two verified sightings of this snake on the refuge indicate that chances of encountering the coral snake are probably slim.

Western diamondback rattlesnake (Crotalus atrox)
The largest of the western rattlesnakes and probably the most dangerous due to its size. Found all across the refuge, primarily in the lower hills.

Speckled rattlesnake (Crotalus mitchelli)
Inhabits the rocky areas of the mountains. Often confused with the tiger rattlesnake (C. tigris). Positive identification is by counting scales on the head.

Sidewinder (Crotalus cerastes)
Easily the most common of the rattlesnakes inhabiting the refuge. It is present throughout the area and is easily recognized by its "horns" just above its eyes. Its unique method of locomotion gives it its name.

Black-tailed rattlesnake (Crotalus molossus)
A large rattlesnake with a black tail and sometimes also a black snout usually found in rocky hill areas.

Tiger rattlesnake (Crotalus tigris)
Active night and day. Back has irregular crossbands ('tiger' markings). Observed in Agua Dulce mountains near abandoned adits.

Mojave rattlesnake (Crotalus scutulatus)
A common rattlesnake found in all areas of the refuge. This snake should be considered very dangerous as its venom is highly toxic, containing substantial amounts of neurotoxin in addition to the regular hemotoxin found in other rattlesnakes. This snake will rarely rattle, even when disturbed.

Other snake species thought to occur on the refuge include the blind snake (Leptotyphlops humilis).

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About Poisonous Snakes

The coral snake is a member of a group of snakes that deposit poison through a chewing action that allows the venom to run into the bite through hollow front teeth. Their venom is a variety of neurotoxin that attacks the nervous system of its victim. The poison of the coral snake is highly toxic and very dangerous.

Lyre snakes poison victims in much the same way as the coral snake - by chewing. The difference being that the lyre snake's grooved teeth are in the rear of its mouth. Not a great deal is known about the venom of the lyre snake but it is not considered to be dangerous to people.

The rattlesnakes are truly an advanced poisonous reptile. They are pit vipers, a group of snakes possessing a heat detecting pit on both sides of the head to help locate prey passing close by. Their fangs are hollow "needles" that extend outward when the mouth is open and can literally "inject" poison into victims. Rattlesnakes are very common in the desert and this, along with their large size, makes them very dangerous snakes. The poison is a type of hemotoxin - the poison destroys blood cells that causes destruction and decay of body tissue.

For your safety: Please obtain information on snake bite prevention before entering the refuge.