March Snarls of snakes in spring
As daytime temperatures get warm in late March, we like to pull up a chair outside and stare at the front steps. As fun as that is in itself, we also have another purpose: to watch for garter snakes (Thamnophis species) as they poke their noses out of small cracks in the concrete. The snakes emerge surprisingly early we usually see them the last week of March and are a wonderful harbinger of spring.
Males are the first to emerge from the hibernacula the technical term for the communal hibernation areas. Females emerge a little later, emitting sex-specific pheromones that attract hordes of males. Many males will converge on a female, sometimes forming a writhing mass of serpentine bodies as they all try to mate with the one female. After mating, the female leaves to look for a place to give birth, while the males may linger, looking for more females.
The story takes an odd twist in some red-sided garter snakes (Thamnophis sirtalis parietalis) in Manitoba, where female mimicry has been observed. Researchers have found that some males emit female pheromones, thus attracting dozens of males to surround them. The she-males may benefit from this behavior in several ways. The swarming males help to increase the body temperature of the she-males, who also benefit from the protection from predators provided by the extra bodies. Some studies have even shown that the mimics are able to achieve more copulations with the females then other males.
Gestation of garter snakes is two to three months. Unlike some snake species that lay eggs, garter snakes are viviparous: they give birth to live young. About 10-70 young are born in a litter and are independent from birth.
Garter snakes can live about five years, are carnivorous and will eat just about anything they can catch and swallow, including earthworms, insects, grubs, frogs, toads, baby mice, and birds eggs. If disturbed, a garter snake may strike, but its bite is harmless to people. More repulsive than the bite is the smelly musky discharge they typically emit as a defense.
- Minnesota Herpetology pages about reptiles and amphibians (jump straight to the snakes)
- More about garter snake courtship
- Manitobas Fantastic Snake Pits by Michael Aleksiuk. Article originally from National Geographic (1975). Republished at Encarta encyclopedia.
- Brochure from Narcisse Manitoba (244 KB PDF), billed as The worlds largest snake dens.