Some snakes reproduce by laying eggs while other species give birth to live young. How snakes reproduce depends on the species and also the location. In cooler regions of the world, snakes reproduce only in spring and summer, while in warm regions they may reproduce all year long.
Like other reptiles, male and female snakes do not have visible external genitalia but they do have different internal sex organs. The male's two testicles are found inside the body. The male snake possesses two copulatory organs, called hemipenes that may be visible as dual bulges at the base of the tail. Unlike humans and mammals, the heimipenes are not connected to the urinary tract and serve only for reproductive purposes.
While the male displays aggressive behavior during courtship by fighting with other males, it is the female who chooses her mate. During sex, one or both of the hemipenes may be inserted into the female"s cloaca or sex organ. After mating, the pair then separate permanently. The semen may actually be stored in the female's body for up to 6 years to fertilize subsequent batches of young.
Egg-laying snakes include all pythons, king snakes, rat snakes, corn snakes and milk snakes. All boas, vipers and garter snakes are born live.