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Rattlesnakes Natural History

Rattlesnakes are "pit vipers" - so called because of deep cavities between the eyes and the nostrils. The pits help detect the presence of nearby warm-blooded prey so that the snake can strike unerringly, even in total darkness.

Only the rattlesnakes can produce the characteristic buzzing noise so often heard in the movies. In the warm deserts rattlesnakes are most active from March through October. They begin their year by being active during daylight hours. As the days become increasingly hot around early May, rattlesnakes become more active at night and spend the day in a spot of shade or a cool den. In addition to these periods of activity, rattlesnakes can be seen "basking" (lying out in the sun) during any month of the year.

Rattlesnakes do not dig their own dens; they utilize preexisting structures. Dens can be abandoned burrows of other animals, brush or wood piles, rock crevices, or about anything else the snake can fit its body under and where it can feel safe. Rattlesnakes may have several den sites in the range of their hunting grounds and sometimes they will sleep in the open. All snakes are carnivorous (they eat animals). Rattlesnakes are effective predators. They eat rabbits, rodents, lizards, frogs and birds. They use their eyes, facial pits and chemically receptive tongue to find their prey and their fangs and venom to kill it. Snakes cannot chew or bite off pieces of their prey; they must swallow it whole. Snakes do not eat every day and sometimes there are many months between meals.

All rattlesnakes are viviparous (their babies are born alive, not hatched from eggs). At birth rattlesnakes are fully equipped with fangs and venom; they are miniature copies of their parents and require no parental care. Baby rattlesnakes are not born with a rattle on their tail but have one little knob called a prebutton. When the newborn sheds, the prebutton will be replaced with a button and then a segment of the rattle will be added with each shed. The single button on a newborn's tail does not produce a sound when rattled. A rattlesnake must have several segments on its tail to produce the "buzz". Rattlesnakes shed several times a year and rattle segments sometimes break off. This fact destroys the myth that rattlesnakes' age can be determined by the number of segments on their rattle.

Newborn rattlesnakes are very small. They have no home territory and are low on the food chain (a lot of animals eat them). This makes for a very nervous little snake! In searching for something to eat and a place to live, newborn rattlesnakes turn up in the strangest places - swimming pools, potted plants, even in houses.

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