Two North American rattlesnake species are commonly called diamondbacks: the eastern diamondback (Crotalus adamenteus) and the western diamondback (Crotalus atrox). Both are large species -- the eastern is the largest rattlesnake in the world -- and both have venomous bites. Adult diamondbacks have essentially no natural predators. Neonate rattlesnakes are not as well protected because of their small size and their variety of predators; in some areas only 17 percent of the young survive their first year.
Rattlesnakes reproduce through a method termed ovoviviparity. Most snakes are different -- most are oviparous, depositing calcified eggs about halfway through their development, in secluded locations. Such snakes usually abandon the eggs after this, leaving them defenseless against a variety of egg-eating predators. Rattlers and other ovoviviparous species, by contrast, retain their eggs until they are ready to hatch. The eggs do not calcify. The membranous capsules rupture during or soon after parturition. By keeping her eggs with her, the rattlesnake regulates the temperature of the developing embryos and eliminates risk of predation, flooding and other catastrophic events.
Timing of Birth
Diamondback rattlesnakes give birth in late summer or early fall. As most of their prey species -- especially rodents, lizards and frogs -- have already produced young by this time, it means that prey are more abundant for the newborn diamondbacks. Species birthed or hatched in the spring don't benefit from this plentiful food. They are large enough to eat mice for their first meal, diamondback rattlesnakes will also eat lizards, frogs and large insects.
A gestating diamondback will generally give birth to up to 20 young in a sheltered location, usually underground. The young are in little danger from subterranean predators while their mother is around, and they remain well hidden from birds and large predators even after they disperse from mom. By starting life in a cave or burrow, the young are also close to potential rodent prey.
Though rattlesnakes don’t exhibit extended parental care; newborn diamondback rattlesnakes are protected by their mothers for a brief time. Young western diamondbacks disperse hours or days after parturition, while eastern diamondbacks remain with their mother until their first shed -- up to two weeks later. This protection provides a significant benefit as the odors associated with their birth can attract predators.
Diamondback rattlesnakes are equipped with potentially lethal venom from the moment they exit their mothers' bodies. Though the young have smaller fangs and produce less venom than adults, they still have enough venom to repel enemies and kill prey.
Though rattlesnakes take months or years to develop effective, multisegmented rattles, every rattler baby is equipped with a hard, terminal scale at the end of his tail. The young exhibit tail-rattling ability immediately -- if this single scale, termed a button, contacts the substrate, it produces a buzzing sound.
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