Rattlesnakes are venomous pitvipers of the family Viperidae and subfamily Crotalinae, and are native only to the Americas. There are 29 different species of rattlesnakes, and 74 subspecies. Though there are many species of rattlesnakes with their own distinctive features, habitats and behaviors, most rattlesnakes reproduce in a similar way, with slight variations based on geography and environment.
Finding a Mate
Rattlesnakes generally mate either in the spring or early summer, depending on their geographic location. Southern species tend to mate when coming out of hibernation in the spring, while northern species often mate in autumn and the females will store the sperm until the following year.
When seeking a mate, males will follow the scent trails provided by females. When a male finds a willing female, he will move his body alongside hers and position his cloaca even with the female's. The male rattlesnakes inserts his hemipenis into the female's cloaca to deposit sperm. Mating may last several hours. Some male rattlesnakes fight over females, using an elaborate "combat dance."
Most species of snakes are what is called oviparous, meaning they reproduce by laying eggs. Rattlesnakes, however, are ovoviviparous, meaning they give birth to live young. Rattlesnakes gestate in eggs within their mothers' bodies until they are ready to hatch, at which point they emerge from in their juvenile form, encased in a clear membrane. Rattlesnakes in southern regions tend to give birth annually, normally in late summer or early fall. More northern snakes will generally give birth once every two years in late spring.
Newborn rattlesnakes do not receive much parental care, with most females abandoning their young after about a week. The babies are well-equipped for survival on their own; young rattlesnakes have a venom as potent as their adult counterparts. Young rattlesnakes will first shed their skins between the ages of 1 and 2 weeks. At this time, they will add the beginnings of a rattle -- a button-like segment that forms the base of the rest of the rattle, which is added to with each successive shedding. Unlike mammals and birds, rattlesnakes do not stop growing when they reach adulthood. Instead, they continue steady growth, accompanied by periodic shedding, for their entire lives.
Rattlesnakes become sexually mature at 4 to 6 years old for males and 7 to 13 years old for females, though this varies by species. When they reach adulthood, rattlesnakes may live for a considerably long time. There is some variation among species and geographic distribution, but most rattlesnakes have a lifespan of about 25 years in the wild, according to the San Diego Zoo. Some captive rattlesnakes have lived as long as 37 years.
- University of Michigan Museum of Zoology: Crotalus Horridus
- Encyclopedia of Deserts; Michael A. Mares
- Encyclopedia of the World's Zoos, Volume 3; Catharine E. Bell
- San Diego Zoo: Rattlesnake
- Rattlesnakes: Their Habits, Life Histories, and Influence on Mankind, Volume 1; Laurence Monroe Klauber