Did you hear a bleating cry in the night this summer? Amphibians have a tough time in the desert. But one such critter, Couch’s Spadefoot (Scaphiopus couchi), has it down. Often called “spadefoot toads” these toad-like creatures, to purists, are not “true toads” because, among other things, they lack the toxin-secreting parotoid gland common to true toads. Does that make them false toads? However, according to the Arizona-Sonoran Desert Museum, “Couch’s spadefoots have a skin secretion that may cause allergic reactions in some humans. Cuts and scratches may become painful, and sneezing and discharge from the eyes and nostrils may also result from the handling of this amphibian.” So don’t handle them.

Couch’s spadefoot is about 3 inches long, has smooth yellowish, greenish, or olive-colored skin with irregular spots of green, brown, or black. It is common in the Tucson Mountains and occurs throughout the Sonoran Desert. They seem to prefer well-drained, sandy soil that supports creosote bush and mesquite. They also occur in grasslands, cultivated fields and along desert highways.

The way spadefoots beat the heat is by estivating (hibernating) underground for about 11 months. They come out during the summer monsoon. They are extremely sensitive to low-frequency vibrations caused by rainfall and thunder.  Those vibrations awaken them.

When monsoon rains form shallow, ephemeral pools, the spadefoots get the signal and come to the surface, in some places, tens of thousands of them, on a single night. And they are noisy. As soon as they emerge, the males set up a chorus of bleating that sounds like sheep or goats; the females eat. The males then silently cruise the ponds in search of a female and eat afterwards. Both males and females eat beetles, grasshoppers, katydids, ants, spiders, termites, fairy shrimp, and almost anything else they can find. They have to eat enough in a few days to last them a year.

A single female can lay 1,000 eggs during one night. The eggs can hatch in as little as 15 hours, and tadpoles can metamorphose into tiny toadlets (one could fit on a dime) in 9 to14 days. During the day, the adults use their spaded feet to dig into the mud. Until toadlets are big enough to dig, they seek cracks in which to hide from the sun.

All will feed until the ephemeral pond is gone, then dig into the mud to wait for next year.

See also:

Creatures of the Night: The Bats

Creatures of the Night: Kangaroo Rat

Creatures of the Night: Grasshopper Mouse

Clever Horned Lizard

Rattlesnakes

Speckled Rattlesnakes

Metachromatic spiny lizards

Venomous Lizards

The greater roadrunner (Geococcyx californianus) may have a clownish reputation due to a popular cartoon series, but the roadrunner is a wily predator.

The greater roadrunner is our largest cuckoo with a body length of 20-24 inches and a wingspan of 17-22 inches. It avoids flying and prefers to run at speeds up to about 15 mph. Even just standing on the ground, it is fast enough to snatch a hummingbird out of the air.

Roadrunners feed on anything they can catch; that includes small birds, snakes, lizards, and mice. Young roadrunners are fed on insects. Roadrunners also eat some fruits and seeds. I recall seeing a roadrunner on my back wall eyeing a family of baby gambel’s quail. Momma quail would have none of this and flew right into the roadrunner, knocking it off the wall.

The roadrunner hunts by walking or running after prey and can jump straight up to capture insects and birds.

According to the Arizona-Sonora Desert Museum:

The pair bond in this species may be permanent; pairs are territorial all year. Courtship displays include, but are not limited to, presenting the mate with a twig or piece of grass and chasing one another.

The nest, which is constructed of twigs, is frequently found in cholla, mesquite, or palo verde. White eggs (three to six) are laid at intervals; if food is scarce the older, larger hatchlings will quickly seize all the food from the parents thus causing the younger, smaller ones to starve. Rarely do all nestlings reach maturity. If not enough food is available, these younger birds will be fed to the other, stronger hatchlings.

Roadrunner skin is heavily pigmented. On cool mornings, the bird positions itself with its back towards the sun and erects its feathers, thus allowing the sun to strike directly on the black skin which quickly absorbs heat energy. This makes it possible for the bird to achieve body heating without unnecessary expenditure of metabolic energy.

Often it seems curiously unafraid of humans. Trotting up close to peer at us, raising and lowering its mop of a shaggy crest, flipping its long tail about expressively, it looks undeniably zany.

Roadrunners are in turn preyed upon by hawks and coyotes, and snakes may go after eggs in the nest. Roadrunners are a signature bird of the southwest. According to Cornell Lab of Ornithology, roadrunners expanded their range during the 20^th Century to include southern Missouri and western Louisiana. Unlike the cartoon “beep-beep,” roadrunners have some distinct sounds, listen here.

See 54 more photos of roadrunners from the Arizona-Sonora Desert Museum digital library here.

The greater roadrunner is the state bird of New Mexico. There are many cultural stories about roadrunners. Some Indian tribes believe that roadrunners help ward off evil spirits. Some early frontiersmen believed roadrunners would help lost people find trails. Cowboys tall tales claim that roadrunners would seek out rattlesnakes to pick fights, or would find sleeping rattlers and build fences of cactus joints around them. In parts of Mexico, the roadrunner brings babies, just like the stork is reputed to do in European legend.

　See posts on other desert birds also:

American Kestrel

Barn Owls

Cactus Wren

Gambels Quail

Harris’ Hawks, Wolves of the Air

Observations on Mourning Doves

Parrots in the desert?

Way of the Hummingbird

Western Screech Owl

There are three common squirrels in the Arizona-Sonoran Desert: the rock squirrel, the round-tailed ground squirrel, and Harris’ antelope ground squirrel. I happen to have all three in my yard, although Harris’ is just a visitor.

The rock squirrel (Spermophilus variegatus) is the largest of the three, up to 1.5 pounds. It resembles eastern tree squirrels. This squirrel is grey with reddish to brownish tinge, usually on its back. It has a large bushy tail. Rock squirrels are found in many habitats, except for the driest part of the desert. They are true omnivores, feeding on seeds, mesquite beans, insects, eggs, birds, carrion, as well as cactus fruit.

I have seen them kill and eat snakes. Upon encountering a snake, a rock squirrel will stamp its feet and wave its tail from side to side while facing the snake. It also tries to flick sand or dirt in the snake’s face with its front paws. This behavior is called mobbing. Researchers in California note that rock squirrels can distinguish between venomous and non-venomous snakes, and change their mobbing behavior accordingly. Yes, they will attack rattlesnakes. Apparently, adult rock squirrels can at least partially neutralize rattlesnake venom. Rattlesnakes have heat-sensing organs which can detect a difference in temperature as little as 0.01 F at one foot. There is some research that suggests that rock squirrels take advantage of this. The squirrel can pump extra blood into its tail to make the tail warmer than its body, thereby fooling the snake into striking at the tail rather than the body.

Rock squirrels dig burrows and may be colonial or solitary. They can be very territorial. They mate in early spring and produce a liter in March. Sometimes a second litter appears in August or September. The rock squirrel may become dormant, holed up in its burrow during cold times, but it is not known to hibernate.

The round-tailed ground squirrel (Spermophilus tereticaudus) resembles a miniature prairie dog, and like them, is a very social animal that lives in small colonies. It is usually grey to beige with a long, black-tipped tail. Adults weigh 6- to 7 ounces. They inhabit valleys and alluvial fans. The round-tails are primarily herbivores, feeding on grass seed, cactus, and other nearby vegetation such as spring flowers, but they will eat carrion. They may sleep for a few weeks in summer until the monsoon arrives. The round-tailed ground squirrel hibernates in the winter. The round-tails are champion small miners. They may have an extensive tunnel network with multiple entrances. They too breed in early spring with pups born in March or April. The pups usually emerge with their mother by May.

The Harris’ antelope ground squirrel (Ammospermophilus harrisii) resembles a chipmunk, but it has a white stripe on its side that chipmunks lack (but chipmunks have white stripes on their faces). Also, chipmunks live at higher elevation, not on the desert floor. This squirrel seems to prefer rocky areas. The Harris’ antelope squirrel usually feeds on cactus fruit, seeds, and mesquite beans, but it will take insects and mice. They will climb a barrel cactus to get the fruit in spite of the spines. The Harris’ antelope squirrel is active all year. During hot days, it uses its busy tail to provide some shade. They did burrows about three feet deep where conditions allow.

All three squirrels have sharp, strong claws used for digging. All three are diurnal, that is, they are most active during the daytime. They all have cheek pouches to store food as they gather it. These squirrels have a variety of vocalizations, some quite loud. You might mistake the sound for a bird call.