Garter Snakes: A Matter of Choice

It’s the largest gathering of snakes in the world, and it’s taking place right now in Manitoba, Canada, as thousands of Red-Sided Garter Snakes emerge from their winter hibernation to mate in a series of limestone pits. I’m Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History. We’re listening to sounds made by the snakes as they rub against each other.

Bob Mason is a professor of zoology at Oregon State University.

“The snakes enter these underground caves and that gets them below the frost line. And they can survive the winter and in the Spring, after eight months of hibernating underground, then they come out and they have this explosive breeding aggregation. The large aggregations are actually made up of almost entirely males. The males all leave hibernation at once, early in the Spring. The females now are very different. They only emerge only a few at a time, and by doing that, they’re spread, they spread the breeding season out over the course of about a month, but that makes a very unusual breeding dynamic in that now you get maybe a thousand males for every one female on the surface of the ground at any one time.”

That high number of males to females makes garter snakes part of the time honored tradition of having females of a species choose their mate from a number of competing males. It’s an efficient way for the most successful attributes of a species to be selected and passed on to future generations. There’s a mystery here though. Professor Mason hasn’t yet discovered precisely why female garter snakes prefer one male to another.

Please visit our web site at www.pulseplanet.com

Pulse of the Planet is presented by the American Museum of Natural History. Additional funding for this series has been provided by the National Science Foundation. I’m Jim Metzner.

Garter Snakes: A Matter of Choice

When it comes to Garter Snakes’ spring mating rites, males compete and females chose.
Air Date:06/01/1998
Scientist:
Transcript:

It's the largest gathering of snakes in the world, and it's taking place right now in Manitoba, Canada, as thousands of Red-Sided Garter Snakes emerge from their winter hibernation to mate in a series of limestone pits. I'm Jim Metzner, and this is the Pulse of the Planet, presented by the American Museum of Natural History. We're listening to sounds made by the snakes as they rub against each other.

Bob Mason is a professor of zoology at Oregon State University.

"The snakes enter these underground caves and that gets them below the frost line. And they can survive the winter and in the Spring, after eight months of hibernating underground, then they come out and they have this explosive breeding aggregation. The large aggregations are actually made up of almost entirely males. The males all leave hibernation at once, early in the Spring. The females now are very different. They only emerge only a few at a time, and by doing that, they're spread, they spread the breeding season out over the course of about a month, but that makes a very unusual breeding dynamic in that now you get maybe a thousand males for every one female on the surface of the ground at any one time."

That high number of males to females makes garter snakes part of the time honored tradition of having females of a species choose their mate from a number of competing males. It's an efficient way for the most successful attributes of a species to be selected and passed on to future generations. There's a mystery here though. Professor Mason hasn't yet discovered precisely why female garter snakes prefer one male to another.

Please visit our web site at www.pulseplanet.com

Pulse of the Planet is presented by the American Museum of Natural History. Additional funding for this series has been provided by the National Science Foundation. I'm Jim Metzner.