Female squirrels never turn down sex

There's a reason female squirrels are so promiscuous, and it can't be blamed on their mothers.

There's a reason female squirrels are so promiscuous, and it can't be blamed on their mothers.

As it turns out, the randy rodents mostly sleep with whoever shows up, according to researchers at the University of Guelph in Ontario.

Whether a female squirrel picks one mate or 14 — the highest one-day tally recorded in the study — has little to do with genetics, said Eryn McFarlane, a graduate student and the project's lead researcher.

"It's due to their environment, to what they encounter," she said. Namely, how many male squirrels are around at the time, she added.

What's more, when it comes to libido, "there's no guarantee at all that daughters will resemble their mothers," McFarlane said in an interview Sunday.

The study, published in the journal Biology Letters, is the first to suggest that genetics have little impact on squirrels' mating habits.

Most research on animal promiscuity tends to focus on the risks and benefits of sleeping around, McFarlane said.

"Classical research kind of suggests that while males should try to mate with as many females as they can find, females should be a little bit more chaste, more picky because they put so much more investment in their offspring," she said.

Having multiple partners can also force squirrels to expend a lot of energy, and make them more vulnerable to predators and sexually transmitted diseases, she said.

"But based on our findings, it doesn't really matter," she added.

Even if the dangers of promiscuity outweighed the advantages, the squirrels probably wouldn't be able to change their behaviour since it isn't passed along to the next generation, she said.

Can't adapt to environment

That shows some species simply can't adapt to their environment, McFarlane said.

The Guelph research team analyzed data collected from 108 mating chases involving 85 female squirrels.

The data come from the Kluane Red Squirrel Project, a long-term field experiment in Yukon that looked at the ecology and evolution of red squirrels.

Since launching in 1987, the project has monitored the behaviour and reproduction of some 7,000 squirrels.

Female red squirrels typically go into heat for a single day each year. As the date draws near, they leave their scent nearby as a signal to males.

When the day comes, they run around to encourage males to give chase and generally mate with all those who show up.

McFarlane said it's unclear why some females attract more suitors than others, and that may be what she looks into next.

"Maybe they advertise more?" she said.