Rattlesnakes are well equipped to colonize and survive in arid habitats; impermeable scales cover their bodies, they do not waste water by urinating and they can detect water from great distances with their incredible senses of smell and taste. By combining these physiological traits with their opportunistic nature, many different rattlesnake species find enough water to survive in the deserts of the southwestern United States and Mexico.
Waiting for a Rainy Day
While precipitation is rare in deserts, many experience brief periodic showers. For example, the Sonoran Desert—home to several rattlesnake species—averages about 15 inches of rain per year. When this happens, rattlesnakes take advantage of the opportunity, drinking from the small puddles they encounter.
Like Water off a Snake's Back
Herpetologists suspect that many desert-dwelling reptiles—including rattlesnakes—collect and drink rainwater that pools on their dorsal surfaces. In 2006, Jim Rorabaugh of the U.S. Fish and Wildlife Service observed sidewinders (Crotalus cerastes) flattening their bodies in a light rain in order to collect rainwater, which they drank. Scientists have also observed Great Basin rattlesnakes (Crotalus oreganus lutosus), southwestern speckled rattlesnakes (Crotalus mitchellii pyrrhus) and desert horned adders (Bitis caudalis) exhibiting the same behavior.
Durable During Droughts
A severe drought struck the Sonoran Desert in the winter of 2005 through the early spring of 2006. In March of 2006, Robert A. Repp and Gordon W. Schuett twice witnessed western diamondback rattlesnakes (Crotalus atrox) emerging from their winter dens to consume water, ice and snow on the ground. During both observations, ambient air temperatures were about 40 degrees Fahrenheit—much lower than those at which rattlesnakes are normally active—which demonstrates the lengths to which these snakes will go to attain water.
Dowsing in the Desert
Snakes' remarkable sense of smell allows them to detect very faint odors. In addition to giving them the ability to follow pheromone trails to winter dens, distinguish between envenomed and non-envenomed prey and detect hidden prey and predators, the combination of the rattlesnakes’ bifurcated tongue, Jacobson’s organ and nostrils allows them to detect water over great distances.
Waste Not, Want Not
In contrast to amphibians or mammals, which lose a lot of water through evaporation, snakes are covered with scales that have a lipid bi-layer, making them largely impervious to water. Additionally, reptiles handle nitrogenous waste differently from mammals; rather than excreting urine, they excrete uric acid. While urine has a high water content, uric acid is a solid or semi-solid mixture with very little water content.
- Blue Planet Biomes: Sonoran Desert Climate
- Journal of Experimental Biology: Sealing Snake Skin
- Arizona-Sonora Desert Museum: Adaptations of Desert Amphibians & Reptiles
- The Southwestern Naturalist: Western Diamond-Backed Rattlesnakes, Crotalus atrox (Serpentes: Viperidae), Gain Water by Harvesting and Drinking Rain, Sleet, and Snow
- Sonoran Herpetologist: Apparent Rain Harvesting by a Colorado Desert Sidewinder (Crotalus cerastes laterorepens) [PDF]
- Elmhurst College: Urea Cycle
- Molecular Phylogenetics and Evolution: Phylogeographic Structure and Historical Demography of the Western Diamondback Rattlesnake (Crotalus atrox): A Perspective on North American Desert Biogeography
- 936 ABC Hobart: Keeping Safe from Snakes
- Herpetologica: Conspecific Scent-Trailing by Newborn Timber Rattlesnakes, Crotalus horridus
- Behavioral and Neural Biology: An Analysis of Prey-Searching Behavior in the Western Diamondback Rattlesnake, Crotalus atrox
- The Southwestern Naturalist: Rain-Harvesting by the Southwestern Speckled Rattlesnake (Crotalus Mitchellii Pyrrhus)