I.

Introduction

Rattlesnake, also called rattler, any of 30 species of venomous snakes characterized by a horny rattle at the tip of the tail, which is shaken vigorously to warn off intruders. Rattlesnakes are members of a larger family of poisonous snakes called pit vipers. Pit vipers have heat-sensitive pits on the sides of their heads that help them detect warm-blooded prey.

Rattlesnakes are found from southern Canada to northern Argentina and Uruguay. In the United States, they occur in all states except Alaska, Hawaii, Maine, and Delaware. Mexico, in the middle of the rattlesnake’s range, is home to 27 of the 30 rattlesnake species. The United States has 15 species of rattlers; a single species lives in Central America; and 3 species occur in South America.

As cold-blooded animals whose body temperature depends on their surrounding environment, rattlesnakes prefer mainly hot, dry locations, such as grassy plains, sand hills, deserts, and brushy or rocky hillsides. They are found from sea level to about 4,420 m (14,500 ft). Rattlesnakes are especially common in areas with abundant rodents, their favorite form of prey.