Rattlesnakes are venomous. If you’re bitten, you should seek medical assistance.  But they’re not particularly dangerous. Here’s what you should know:

Rattlesnakes rarely bite humans unless stepped on or roughly handled.

Only about fifty percent of defensive  bites inject venom.

Fatalities from rattlesnake bites are virtually unheard of in otherwise healthy individuals. In the rare instances where a bite causes death, the death is generally the result of  an underlying health issue exacerbated  by the bite, rather than from the bite itself.

In 2016 , rattlesnake venom contributed to the death of a single individual  in the United States who had an underlying medical condition. In the same time period, toddlers younger than four years old shot 51 individuals in the United States, about half of them fatally, while stairs injured over a million people and killed 12,000.  Now think about this:  there are people every day in this country who walk down stairs — with toddlers!  How reckless is that?

Rattlesnakes are pit vipers of the genera Crotalus and Sistrurus. They are easily recognized by their broad, flat heads, heat-sensing pits located below and forward from their eyes, and their blunt tails, ending in distinctive rattles. Viperines also possess a set of hollow fangs, visible when the snake is yawning or striking.

Like all living reptiles, they are ectothermic, which means that they are unable  to increase their metabolic rate in order in response to low temperatures as endothermic species (such as mammals and birds) can. Therefore, they must rely on external heat sources, such as sunlight or warm rocks to regulate their body temperatures.

Rattlesnakes are ovoviviparous, giving birth to live young, rather than laying eggs. The young are born between August and October. The female maintains a maternal bond with her offspring that lasts at least until the neonates’ first shed.

Neonates are not born with rattles. Their tails end in a black nub called a “button.” Each time a rattlesnake sheds (usually once or twice a year) a segment is added to the rattle. When a frightened rattlesnake vibrates his tail,  friction between these delicate segments creates the distinctive buzzing sound   While only rattlesnakes have rattles, this nervous tail-vibrating behavior occurs in other species as well.

Male and female rattlesnakes are of comparable size at birth. When a female rattlesnake enters reproductive maturity, her growth slows somewhat, leaving the average adult female smaller than the average adult male. Although one can’t accurately determine gender without a close examination, it’s possible to make an educated guess by looking at the tail. Males generally have long, slender tails, while females have shorter and stouter tails.

The pattern on a rattlesnake’s tail is as distinctive as a human fingerprint.
If you encounter rattlesnakes regularly where you live, try photographing them for later comparison. Before long, you may find yourself greeting old friends.

In the wild, rattlesnakes tend not to live more than about twenty years, but well-cared-for captive snakes have been known to live for nearly thirty. It’s not possible to accurately determine a rattlesnake’s age by counting the rattle segments, although you can make an educated guess if the rattle is fully intact. Unfortunately, the rattle is a rather delicate structure and prone to breakage, so older snakes often have incomplete rattles.

Senses

Rattlesnakes perceive the world in ways that differ somewhat from the way we humans perceive it.   Their eyes are set widely apart, on the sides of the head, rather than in front. This gives them good peripheral vision, but limits their depth perception. In order to determine how far away an object is, rattlesnakes will sometimes shift their heads from side to side, using parallax to get a better sense of the distance.

In addition to seeing with their eyes, rattlesnakes and other pit vipers are able to pick up thermal information via the specialized heat sensing pits located in front of and below the eyes, allowing them to image the world in a manner similar to that of a thermal imaging camera.

It’s a common misconception that snakes cannot hear, but  can only feel vibrations through the ground. It is true that they have no external ear structure, but their inner ears are similar to ours. Sound is transmitted to their inner ears via their muscles and bones. Far from being deaf, rattlesnakes can actually hear via both air and ground vibration. They hear more clearly through the air, but can distinguish a wider range of frequencies through the ground.

All snakes use their tongues to smell their environment. The tips of the forked tongue collect molecules from the air or from a surface and transfer them to a pair of tube-like structures called the Jacobson’s Organ in the roof of the snake’s mouth. Since each tip can sample the scent separately, the snake is able to compare the samples and determine on which side a scent is stronger, making it easier for the snake to follow a scent trail.

Rattlesnakes are social creatures who care for their young, maintain lifelong bonds with their siblings and form friendships within the den. They den communally, returning to the same hibernaculum each winter to brumate – a state similar to that of hibernation in mammals, differing in that brumating reptiles can survive reduced oxygen levels, but do require water occasionally. Time spent in hibernacula varies somewhat from one species to another and from one climate to another. The Northern Pacific rattlesnakes in my area emerge from brumation in early March but remain on the den until mid-May before dispersing for the summer. By the end of October, most have made their way back to their hibernacula, but as late as mid-November it is still possible to find a few individuals sunning on the surface of the den.

The dependence on traditional den sites is an important consideration for wildlife managers.  A rattlesnake removed from the vicinity of the den and released elsewhere will become disoriented and cease to eat, dying slowly from starvation, or freezing to death when he is unable to find his way to a den for the winter. For this reason a rattlesnake found in unusual circumstances, where his place of origin cannot be reliably determined should not be released but rather placed with a zoo or licensed wildlife rehab facility, where he can be properly cared for.

Rattlesnakes are ambush predators. Rather than actively chasing prey, they choose a suitable location near a well-used rodent trail and wait. When a rodent passes nearby, the rattlesnake strikes and injects venom and then follows the animal’s scent trail to the remains.  Some ground squirrels use this behavior to their advantage by rubbing the shed skins of rattlesnakes into their fur. In captive studies, rattlesnakes sought out squirrel-scented patches of material, but avoided similar patches that had been additionally rubbed with rattlesnake sheds, suggesting that the squirrels’ behavior may reduce their chances of falling prey to a rattlesnake.

Male rattlesnakes, like the males of other species, compete for the right to breed with females. Unlike many other species, however, they do not bite or  injure one another but instead compete in ritual wrestling matches, rising up into a vertical position, and pushing against each other, each trying to force the other to the ground.

After giving birth in late summer or early autumn the female bonds with and protects her offspring, at least until the babies shed for the first time, Some researchers report seeing adult males apparently guarding youngsters as well.