Why are female squirrels promiscuous?

TORONTO - Why do female squirrels entertain as many suitors as available?

Canadian researchers say rampant promiscuity among female squirrels in the mammal world is linked to how many males are knocking at their door.

“Their behaviour is overwhelmingly influenced by opportunity,” says Eryn McFarlane of the University of Guelph near here.

“We found the more males in the area interested in participating in the mating chase, the more squirrels she will mate with,” says McFarlane who worked with other researchers to find the truth about rampant promiscuity among female squirrels.

“There are no strong ties between mating behaviour and genetics in red squirrels. So even if the costs of mating with many males outweighs the benefits, there doesn’t seem to be much capacity for them to evolve lower levels of promiscuity.”

Although it makes sense for male squirrels to have as many mates as possible to ensure the most offspring, risky promiscuity doesn’t always make sense for females, says McFarlane.

But female squirrels are less than picky when it comes to mating, often entertaining as many suitors as possible, according to her.

But “having multiple partners means more energy expended on mating, increased exposure to predators as well as increased potential for the spread of sexually transmitted diseases,” she says.

“Promiscuity also encourages harassment from male squirrels trying to coerce them into having sex.”

Interestingly, a female red squirrel goes into heat for only a single day each year. On that day, she runs around to encourage interested males to give her a chase and mates with as many as are available, according to the researchers.

Their findings appear in the Royal Society Journal Biology Letters.