Squirrels seem so innocent.
Busy hiding their nuts for winter. Crossing hydro lines with the greatest of ease. Wowing us with their fluffy, fluffy tails.
But researchers at the University of Alberta have now documented male red squirrels actually killing the babies of other squirrels.
The research, published in Ecology, is the first documentation of this murderous behaviour and is linked to an abundance of food.
“It’s called sexually selected infanticide,” lead author Jessica Haines said in a statement. “It’s when a male kills another male’s offspring to increase the chances that he’ll be able to father pups of his own when the female breeds again.”
The biologist first witnessed this while doing fieldwork in the spring of 2014.
She found dead pups and later, used genetics to learn the culprit was not their father, but the father of the offspring in the mother’s second litter.
Male #squirrels kill offspring of rivals in years when food is plentiful, according to study by #UAlberta biologist @JessAHaines: https://t.co/J1iAxeZTmA pic.twitter.com/lrnI5H7d5d
— UAlbertaScience (@ualbertaScience) March 15, 2018
And, this only only happened when white spruce cones, a staple in the red squirrel’s diet, are plentiful.
These are called “mast years.” That’s also when female squirrels will produce more than one litter.
The male squirrels seem to have figured out this reproductive bonus and will kill babies in order to give them a second chance at fatherhood.
It’s something that does happen in species that live in groups, like harems.
But the researchers were surprised to see it in squirrels, which live alone and don’t “monopolize a single female.”
“It’s fascinating that they change their mating behaviour to commit infanticide in mast years, particularly because it means they predict the cone availability in the upcoming fall,” Haines added.
In perhaps the most fascinating squirrel thread on Twitter, Haines offered the origin story of her research.
It’s worth a read.
I am a biologist and the inspiration for my research comes from many places. But this particular paper is unique for me, because it all started with these two squirrels. pic.twitter.com/GWwsTLKsqP
— Jessica Haines (@JessAHaines) March 15, 2018
Photos University of Alberta
