This time of year, Brian Nigbor usually has to spend some time cleaning up the mess of leaves and branches left by the squirrels that nest in a big maple tree in front of his North Side home. But not this year.
“You just don’t see them around much,” says Nigbor, 54. “It’s nothing like normal. Where did all the squirrels go? It’s so weird.”
The mild winter followed by this summer’s drought and unusual heat are probably to blame, according to Steve Sullivan, senior curator of urban ecology at the Peggy Notebaert Nature Museum in Lincoln Park.
Normally, a large number of squirrels die over the winter either from cold or starvation, but more survived last winter, says Sullivan, who is the lead investigator for Project Squirrel, a nationwide squirrel study. As a result, the young litters are facing competition with older and stronger squirrels.
“I suspect what has happened is that all of the spring babies died, and a good number of last year’s squirrels have died,” Sullivan says. “We had a weird winter that is going to influence our summer numbers, and then we had a summer drought that is going to influence the next three generations of squirrels.”
The unusual heat that’s been baking Chicago also might have hurt squirrels, which are especially sensitive to warm weather and are prone to overheating, says Joel Brown, a professor of biological sciences at the University of Illinois at Chicago.