Acting tough may work for Clint Eastwood, but for male garter snakes acting girly is the path to success, says Oregon State University zoologist Robert Mason. Every spring tens of thousands of garter snakes emerge from under rocks and deep within caves across the northern United States and Canada, cold and sluggish from a winter's sleep. Males slither out first, feverishly attempting to warm up so they can be first in line to surround the emerging females. The suitors end up in a wriggling mass of 10 to 100 snakes.
But sometimes the girl is a guy: The snake at the center of the ball may be a male emitting fraudulent female pheromones. Mason believes these she-male snakes use the ruse to warm up quickly so they can escape birds and other predators. "They keep it up for a day or so and drop it when they're warm enough," he says. "There are very few cases in the animal kingdom where female mimicry is used to increase overall fitness rather than just to dupe other males. But in this case it accomplishes both tasks nicely."