Desert Habitat, pt.3

In the past two blogs, we have explored deserts and the plants which inhabit them.  Animals native to these habitats have general adaptations for coping with temperature extremes, aridity, and finding water, food, and shelter.  Strategies include hunting during cooler hours including at dawn, dusk, or overnight; obtaining water from sources other than standing water; burrowing underground to avoid temperature spikes and solar radiation; ability to conserve water in their body; ability to dissipate body heat; and being well-camouflaged.  Look for each of these adaptations in the following species that live in our desert regions.

The greater roadrunner, Geococcyx californianus, can only fly for several seconds at a time, but can reach speeds up to 17mph when running.  They hunt early in the morning, retiring to shade when temperatures heat up mid-morning.  Water requirements are met from foods including grass and prickly pear cactus, plus prey that includes lizards, scorpions, and rattlesnakes.  Roadrunners do not urinate, but can excrete salt and save the water.  They have an un-feathered area under their chins used to dissipate body heat.  Ord’s kangaroo rat, Dipodomys ordii, is another species that gets all of their water requirements from the seed they eat.  Individuals live in underground burrows, coming out only at night to feed.  They conserve water in their bodies and do not sweat or pant.  They have many predators, but with a 9-foot jump and excellent hearing, they are hard to catch.  Seeds are collected and stored in their burrows, and they will gain 50% more water from the underground humidity before being eaten.

Horned toads, Phrynosoma spp., are small, ant-eating lizards with thick scales to conserve water and deter predators.  To escape a predator, these animals can squirt a directed stream of blood from their eyes up to five feet away.  They are sandy-colored with undefined outlines allowing them to easily hide amid rocky outcrops.  Normally active during the day, they can retreat to burrows or under rocks if temperatures become too hot.  During winter, horned toads will spend a period of inactivity, called brumation, in underground burrows.  The Gila monster, Heloderma suspectum, is another lizard with armor protected skin marked with black and pink coloration that camouflages them well in sandy soils.  They shelter from daytime heat under rocks and shrubs, emerging in early morning or evening to hunt small mammals, lizards, insects, and bird eggs.  One of only two venomous reptiles in North America, their venom adversely affects their prey’s nervous system.  The short, thick tail stores water in fatty tissue for use when needed.

The tarantula, Aphonopelma spp., shelters in deep burrows lined with silk to prevent the sand from caving in.  They are nocturnal hunters of insects, arthropods, and small lizards with a bite that delivers a small amount of venom to stun their prey.  Venom immediately starts to break down tissue to liquify the meat, allowing the spider to use sucking mouth parts to draw in its meal.  The Western coral snake, Micruroides euryxanthus, is brightly colored with red-white-black-white banding and venom that is twice as deadly as most rattlesnakes.  They are very secretive, living under rocks or buried in the sand.  Coming out at night or on some overcast days, they hunt for lizards and other snakes.  Venom causes rapid paralysis and respiratory failure, although due to their small size and small amount of venom injected, they are not a threat to humans.

Like many environments, a healthy desert community exists when plants, animals, and habitat are all present and undisturbed.  With much of the life in deserts underground, walking off trails and driving off roads can negatively impact what is under the surface.  Removing plants and rocks used for water and shelter is equally damaging.  I encourage you to get out, observe, and enjoy this unique habitat, or research many of the fun and interesting adaptations at a local natural history museum.

^{Pictures above clockwise: Bark scorpion by Josh More, May 2014; Cactus wren by Mick Thompson, Feb 2019; Jackrabbit, by Mark Gunn, Mar 2014; Javelina, Sonora Desert, by Richard Bonser, Jan 2005; Tarantula hawk wasp by Jim Mulhaupt, May 2010; Sonoran mud turtle by Grigory Heaton, Sep 2022; Round tailed ground squirrel by Wendy Miller, May 2022; Hoary bat by Michael Pennay, Sep 2009; Cactus deermouse by J.N.Stuart, Oct 2011}