Tag: rattlesnake tracks

Reading Land: Decoding Rattlesnake Tracks

I thought I knew something about rattlesnakes before I moved to Arizona. I had spent decades in Montana, where I had interacted countless times with the single species that lives in that state, Crotalus viridis, known as the prairie rattlesnake. The signs that these snakes left of their presence on the land were usually limited to shed skins, skeletal fragments, or scats. I rarely saw their tracks for the simple reason that the prairies that I roamed in were completely covered with grasses and other plants.

Most snakes leave tracks like this, their serpentine form easily recognized.

Here in southern Arizona, a different situation presents itself, for there are plenty of open areas in the desert where tracks appear readily and often. When I first arrived here, I thought that snake tracks were snake tracks and not much more – until I discovered that rattlesnakes often leave very distinctive trackways. Unlike most other snakes, rattlesnakes crawl in a distinctive manner, known as caterpillar motion. Their bodies remain very straight (rather than sinuously curved) when they travel across the landscape. If a rattlesnake is in a big hurry, it will leave “S”-shaped tracks, curving and sinuous like other snakes. But these vipers are rarely in that much of a hurry, so it is far more common to find their straight trackways, a hallmark of their kind.

Rattlesnakes most often leave very straight, distinctive trackways like this one found on the dusty floor of an Arizona barn.

When rattlesnakes want to stop and rest, they invariably curl themselves into tight, circular shapes. If they have rested on a sandy or dusty substrate, they will leave behind another very distinctive rattlesnake trademark, a circular crater often dug one or more centimeters deep into the ground. No other Arizona snakes that I know of assume this distinctive at-rest posture.  Rattlesnakes do the great majority of their hunting in such a stationary, circular posture, where they wait, motionless, for prey to come by. Thus, these snakes are referred to as “ambush predators.”

When at rest, rattlesnakes curl into a tight, circular shape, leaving distinctive craters in the substrate. Here, even the snake’s rattles have left a clear impression in fine, dusty soil. The blue ruler, a standard item in many of my track photographs, measures 6 x 1 inches. For this part of Arizona, a crater of this width represents an average-sized western diamondback rattlesnake about three feet in length.

Why did such behavior evolve in these reptiles? Ambush predators rely on concealment. Most animals, including people, immediately recognize the unmistakable serpentine form of a snake. By assuming a non-serpentine look, rattlesnakes can hide from both their prey and their predators more effectively. I have encountered many diamondbacks and other rattlesnake species, and I can say with conviction that when these creatures are at rest in their usual circular posture, they can be extremely difficult to spot. That is one reason why I usually wear heavy boots and snake gaiters when I am hiking during the warm months. A little prevention can go a long way. Some of the rattlesnake species in southeastern Arizona are exceptionally potent. The average cost of treatment for snakebite is now over $75,000!