ekiNative to the Americas, the sound of the rattlesnake’s shaking tail is infamous across the world. But there’s a lot more to know about these venomous snakes than just the sound of their rattle says Beki Hooper.
Where do rattlesnakes live?
There are 36 species of rattlesnakes, and while they range from Argentina to Canada, they are most commonly found in southwestern USA and Mexico. Arizona holds the record for the highest number of rattlesnake species, with a whopping 15 species found within its borders.
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Each rattlesnake species has its own specific habitat requirements, but they are generally found near open, rocky areas, often in arid environments.
What do rattlesnakes look like?
Rattlesnakes are known for their triangular heads, thick bodies, and the rattle at the end of their tails. But if you see a snake that is rattle-less, it might still be a rattlesnake — young snakes and some adults do not possess rattles.
Rattlesnakes tend to keep camouflaged with band, spot or diamond patterns on their skin. They also tend to be earthy colours, such as brown, olive, yellow and grey.
How big are rattlesnakes?
There is quite a lot of variation in their size. The smallest species, aptly named the pygmy rattlesnake, is usually less than 18 inches long, while the longest species, the eastern diamondback, can reach 8 feet.
Why do rattlesnakes rattle?
Scientists generally agree that the rattle has evolved to advertise the snakes’ presence. This has nothing to do with hunting, and everything to do with self-protection.
One of the last things a snake wants is to be stomped on by a passing animal, and one of the last things a passing animal wants is to step on a rattlesnake and get bitten.
Rattlesnakes therefore use their rattles to say: ‘Hey, I’m here, don’t step on me!’
When other animals get too close for comfort, rattlesnakes can increase the frequency of their rattle. This creates the illusion that the snake is closer to the animal than it actually is. Not only does this decrease the chance of the snake getting stepped on, it might also confuse potential predators about the snake’s location.
How does the rattle work?
The ‘rattle’ at the tip of rattlesnake tails is made of hard rings of keratin (the same material as our nails).
The rattling sound is made when the rattlesnake vibrates its tail and these hard rings hit against one another. This vibration is one of the fastest sustained movements that any vertebrate can make — faster, even, than the flap of a hummingbird’s wings. Some species can shake their tails more than 90 times per second!
Every time a snake sheds, a new ring (also known as a button), is added to the rattle. But this doesn’t mean that older rattlesnakes have longer rattles, because rings often break off the end due to wear and tear.
What do rattlesnakes eat?
They usually eat small animals, such as small birds, rabbits and rodents.
Ambush predators, rattlesnakes lie in wait for prey to come to them. Between the eye and the nostril is a heat-detecting organ called a ‘pit’. This organ allows them to detect warm-blooded animals, even in the pitch black.
When a prey animal gets close enough, the snake strikes. Their venom kills quickly. Death is usually caused by the venom’s effect on the prey’s blood, which can lead to catastrophic internal bleeding or heart-stopping clots.
Sometimes, if the prey animal doesn’t die immediately, the snake tracks the dying creature through the landscape. They do this by flicking their tongue into the air and then touching it to the roof of the mouth, where the Jacobson’s organ sits.
Jacobson’s organs are common to snakes and lizards, and allow the animals to ‘taste’ the air for very subtle scents, such as that of dying prey.
How do they drink?
Many rattlesnakes live in arid regions, and in these dry landscapes it is often water rather than food that is extremely limited. In these regions, rattlesnakes have been seen coiling up and flattening themselves so that water collects on their scales. The scales have special surfaces that help water ‘stick’ to them. This means the snakes can lap water up from themselves — a clever solution in a parched landscape.
Are they sociable?
While many species are solitary, some rattlesnakes are surprisingly sociable. For example, pregnant timber rattlesnakes have been found to form ‘birthing rookeries’, large gatherings of expectant females. Relatives also tend to hang out with one another, suggesting the snakes are able to recognise kin.
Does anything threaten them?
While rattlesnakes are a tasty meal for quite a few predators, including hawks, kingsnakes and weasels, it is humans that pose one of the biggest threats. Rattlesnakes that encroach on human property are often killed. This is happening more frequently because dry weather is pushing rattlesnakes into water-rich gardens, and developments are being built in rattlesnake habitat.
Besides the threat of being killed by people, habitat fragmentation caused by urban development also poses a long-term risk to the snakes. Cut-off from other populations, they are forced to breed with relatives, and this can lead to health problems.
How dangerous are rattlesnakes to humans?
Rattlesnakes are responsible for the majority of the 8000 or so snakebites that occur every year in North America. However, thanks to medical care and antivenom, the bites are rarely fatal; around 5 people die from them per year.
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A bite from a rattlesnake can lead to lasting injuries though. Around 10 to 44% of rattlesnake bites will lead to long-lasting health effects, so it really is something best avoided and should always be treated as a medical emergency.
Luckily, rattlesnakes don’t want to expend their valuable venom on an inedible human. They only tend to bite if they are stepped on or are otherwise threatened, and they will usually rattle before they bite.
So, it’s probably best to keep an ear out for that infamous rattle if you are spending time in the American wilderness!
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