There are about 30 different species of rattlesnake in the world. The easiest way to identify a rattlesnake is by his tail. A rattlesnake has a distinctive tail made of hollow, interlocking segments of keratin that, when they rub together, create the signature rattling sound. If you're trying to determine the age of a rattlesnake, the tail is your best clue.
When the snake is about 2 weeks old, his first rattle section will form, and every time he sheds a new section is added to the tail. Baby and juvenile snakes have a lot of growing to do, and they shed more often than adults. Once a snake is a few years old, he may shed two or three times a year, depending on his diet, overall environment and growth rate. In some cases, a rattlesnake may lose rings on his rattle.
Counting the Rattles
Unless you know when the snake hatched, you can't determine the exact age of a rattlesnake, but you can count the rattles to figure a rough estimate as to how old the snake is. On average, you can estimate the snake added two or three rattles for each year of his life.