How to Tell If a Coast Garter Snake Is a Boy or a Girl

Measure the size of the snake with the tape measure. Avoid touching or irritating the snake. Coast garter snakes reach up to about 2 feet in length, but female snakes are typically larger than male snakes. A large female snake is able to have more young than a small snake, so females tend to become very large. A coast garter snake that is closer to 2 feet long is more likely to be female. In addition, female garter snakes tend to be thicker than males. However, not all females are large and very young snakes are similar in size, regardless of gender.

Examine the tail area. The tail of a male garter snake is larger, longer and thicker than a female's. Male snakes have a subtle bulge at the base of the tail, whereas female snakes have tails that taper more sharply. This is the most reliable cue for visually determining gender, but requires practice to see the difference between a male and female tail.

Observe the snake's behavior. While behavior is not always a good indicator of gender, female garter snakes tend to be slower and more sluggish, and males tend to be quicker and more active.