For many decades, snake reproduction has fascinated people throughout the world. Part of this is due to their unusual anatomy (for tetrapods anyway). Males have doubled sex organs called hemipenes that are tucked and inverted inside the tail.
This gives males of most species a noticeably longer tail length than females and males also show a more gradual taper to their body from head to tail tip. When ready to copulate, males evert their hemipenes and typically use only one hemipenis at a time. Why they have evolved two organs is still a mystery, and perplexes many evolutionary biologists.
Copperhead Springtime Courtship and Mating.
Male is on the left; watch his attentive chin rubbing, tongue-flicking, and nudging.
Tactile stimulation, pheromone communication, or a combination?
In spring or early summer, female snakes produce attraction pheromones, indicating their readiness to mate. They broadcast these compounds as they crawl, leaving a scent trail that males can follow. In some species, physical interactions (called “combat dances”) between competing males can occur.
Most of our Western Mass snakes mate in the spring, but a few species wait until summer. Some females give birth or lay eggs the same year they mate, others are able to store sperm for half a year or more. There are many aspects to courtship once males and females get together, and most of these behaviors have yet to be adequately studied in the field.