Nature Notes: Rattling Rattlesnakes

BY MILENIUSZ SPANOWICZ

Hiking through the Chihuahuan Desert, the excitement of seeing animals in their natural habitat is an integral part of our escape to the wilderness.  But there are some animals that we may not be so excited to see, like rattlesnakes. Snakes prefer to hide rather than confront a threat. But when in danger, the rattlesnake gives warning with its percussive rattle.

The sound is produced when the rattlesnake vigorously vibrates its tail, making individual segments of its rattle hit against each other. The sound is amplified by multiple connections of interlocked segments within the rattle. The small, empty spaces between the different segments act as small resonating boxes. 

Rattlesnakes have special muscles that allow them to vibrate their tails for a prolonged period of time.

A snake’s skin is composed of individual scales which are shed as they grow. The shedding process starts at the snake’s mouth, and the old skin peels off the snake’s body, turning inside out in the process. This process is common to all snakes.

Rattlesnakes have a tail with an enlarged and rounded tip that is covered with a single large scale. During shedding, the piece of skin that covered the tail scale is turned inside out and peeled off the end of the tail but stays attached to the very tip of the tail and forms a new rattle segment each time the skin is shed. 

Since they haven’t yet shed, newborn rattlesnakes will have no tail segments and can’t rattle. But in the first few weeks of its life, the young rattlesnake will shed its skin for the first time and add the first segment of the rattle. 

It takes a couple of sheddings before the rattle can start functioning properly, at first emitting only a very faint rattling sound. Gradually, every new segment makes the rattle louder. As the snake’s body grows, each segment gets bigger and bigger. 

In the Trans Pecos area, rattlesnakes normally shed their skin 3 – 4 times a year. This means that a 10-year-old snake could have a rattle consisting of up to forty segments! This doesn’t happen, however, for as the snake ages, the rattle is gradually worn out, and terminal segments are broken off. Under normal conditions, the rattle always consists of several segments in good, working condition.

The rattlesnake protects its instrument as best it can by holding the rattle up while it crawls around, not dragging it on the ground.  But sometimes the rattle can be broken off at the base of the tail. When this happens, the rattle will again re-grow, segment by segment, as the snake sheds. 

A rattlesnake’s rattle is very conspicuous and a clear warning of the snake’s presence. That warning is beneficial to both parties. The rattlesnake doesn’t have to waste its venom or risk injuring its teeth biting an animal it can’t eat, and the animal that crossed the path of the rattlesnake may go by unharmed. 
Nature Notes presents natural wonders of the Chihuahuan Desert in this column every other week. Nature Notes is produced by the Chihuahuan Desert Research Institute and Marfa Public Radio and is sponsored by the Meadows Foundation and the Dixon Water Foundation. Tune in to Nature Notes on KRTS-93.5 FM on Tuesdays and Thursdays at 8:35 a.m. and 4:45 p.m. and again on Thursdays at 7:06 p.m. Visit us online atnaturenotesradio.org.