Mojave Rattlesnakes

Mojave Rattlesnakes are not found North and East of the Pecos River

Published Oct 27th 2002 in Wildlife

“I have found a Mojave Rattlesnake in Midland County. I would like to bring it in to show you, and you can have it for a specimen.” When the staff of the Sibley Nature Center gets such a call (and we get a half-dozen or more like it every year), we get out the books and await the arrival of the visitor.

Almost always the snake is dead, killed out in exurbia such as Greenwood or Gardendale. Sometimes the body is "pretty-well" mangled and the head is missing, which makes identification a little difficult. Sometimes the snake is a young Diamondback, and once in a while, someone brings in a Prairie Rattler. The folks want the snake to be a Mojave, and believe it must be, and often are adamant that it is.

So far, every time we have had to tell the folks, “That is not a Mojave Rattlesnake!” We probably will always have to tell folks it is not a Mojave, for they prefer much more arid and rockier country. None of the identification books show any records east of the Pecos River. As far as we can determine, the closest specimens on record are from near Fort Stockton. That is not too far, not for us humans, but Crotalus scutulatus does not do well when sympatric species are present. In other words, they do not do well with competition from other species of rattlesnakes with similar food preferences and of similar size. And here on the Llano Estacado we have plenty of Prairie Rattlesnakes, which are also two to three feet long and also eat ground squirrels and kangaroo rats and other such smaller rodents.

“It isn’t the same as the Diamondbacks I’ve killed – it is more aggressive, and the black bands and white bands on its tail are narrow.”

“On a Mojave the white bands are wider. Mojaves are not more aggressive – they flick their tail slowly, back and forth, with a metronome’s regularity, and lower their heads to the ground. Let’s look at the snake’s head, too, for the scales between the eyes of a Diamond-back are even sized, while a Mojave’s have a double row of larger scales. On a Mojave, the white line behind its eye goes back toward the length of the body, not down toward the mouth. I have found one book that shows the base of a Mojave rattler’s tongue to be a bright blue, while a Diamondback’s is always all black. And another thing, the Mojave Rattlers I have seen in Arizona have an olive or greenish background color.”

Mojave Rattlesnakes have neurotoxic venoms, while the Massasauga, Diamondback, and Prairie (the rattlesnakes of Midland County) have hemotoxic venoms. Hemotoxic venoms are saliva enzymes that begin the process of digestion, since the prey animal is not masticated or physically broken apart while being eaten. Neurotoxic venoms (such as the Mojave’s) cause paralysis, heart and respiratory malfunctions, and the impairment of the senses. The Mojave Rattler’s venom is almost as potent as a cobra’s, making it the most dangerous serpent north of Mexico.

Folks that live over in the sand dunes from Crane to Ft. Sumner often have told us about the Sidewinder Rattlesnakes that live in the dunes. When specimens are examined, they always turn out to be Prairie Rattlesnakes. “But they throw their body forward – their tracks are not single lines – there are often gaps in the trail, just like the pictures you see of a Sidewinder’s trail.” No specimen of a Sidewinder has ever been recorded east of Arizona, ever, but folks in Andrews, Monahans, Portales, have all adamantly assured me of the presence of the species in their neighboring sand dunes.

Why do so many people so adamantly claim the existence of Sidewinders or Mojaves? I know that folk knowledge is powerful – that such information can spread rapidly, and that folk knowledge is believed passionately. But anybody can own a reptile identification book – and anybody living at or beyond the edge of town should have a reptile identification book in the house. The information in the paragaraph above was easy to find in several books. They only cost twenty bucks at any bookstore. But folks do not spend the twenty bucks, but instead rely on what Cousin Mary or Uncle Hernando told them, and who heard the information from somebody at work or at church.

Why folks so desperately want to find a Mojave or Sidewinder Rattlesnake? Is it because of our human fascination with the weird, strange, or extremely scary? Does it come from the same impulse that makes horror movies so popular? Or the same impulse that makes a crowd form around a horrible wreck and stare at the emergency workers desperately struggling to save someone’s life? Is it that impulse that makes us believe that “NEWS” is stories of bad things happening – even if the event is 2000 miles or 20,000 miles away?

We humans are mighty strange critters, that is for sure!