Hunters can collect only male rattlesnakes 42 inches or longer, and once they catch one and fill out the proper forms, their season is over. Females are protected. Figuring out a rattlesnake's sex alone is a deterrent for the casual hunter. Once the snake is caught, its head is secured in a plastic tube and the hunter must count its subcaudal scales, the enlarged plates just before the tail. If it has 21 or more, it's a male.