A squirrel in the attic is a timing problem as much as an animal problem. The U.S. Forest Service says female fox squirrels come into heat twice a year, in mid-December or early January and again in June. Because a squirrel may have young in the attic, ask whoever does the work how they will make sure none are inside before the hole it uses is closed.
When do squirrels breed in Michigan?
It depends on the species. The Forest Service describes each one across its whole range, not Michigan alone:
- Fox squirrels. Females come into heat in mid-December or early January and again in June. The earliest litters appear in late January, and most births fall in mid-March and July. Two litters a year is normal, though a yearling female may have only one. A litter averages three young.
- Red squirrels. Breeding peaks from March to August, but can start as early as January and run as late as October. There is usually one litter a year, occasionally two, of four or five young.
The National Park Service says eastern gray squirrel females have one or two litters a year, depending on how much food is available. Fox squirrel young are weaned at 8 to 10 weeks and may not be self-supporting until 12, according to the Forest Service.
Which squirrel is in the attic?
The hours you hear it are a clue. The National Park Service describes flying squirrels as nocturnal, so noise only after dark may be one of them. The Forest Service describes red squirrels as active by day, year-round, and lists man-made structures among the places they nest; the Park Service says gray squirrels are less shy than most animals about being out in daylight. Raccoons, which the Forest Service calls typically nocturnal, make night noise too.
Flying squirrels carry a rare health risk of their own. The CDC links rare U.S. cases of typhus, called sylvatic typhus, to exposure to flying squirrels and their nests, and advises avoiding contact with both. Rabies is not the usual worry: the CDC says squirrels hardly ever have it. For Michigan’s rules on flying squirrels, see the DNR’s squirrel species page.
What goes wrong if the hole is sealed too soon?
Young still in the attic can be shut in. Before any opening is closed, ask the operator two things: how they will get the squirrel out, and how they will make sure no young are left inside.
On a call about squirrels, the useful details are when the noise started and where you think the squirrel gets in.
If young squirrels are found and the mother is gone, they are not a household project. The U.S. Fish and Wildlife Service says a wild animal that needs help should go to a licensed wildlife rehabilitator, and that most states require a permit or license to rehabilitate wildlife.
How do you keep squirrels from coming back?
The National Park Service’s rodent-proofing manual, written for its own staff, says gray squirrels may gnaw their way into attics, nest in the insulation and chew electrical wires. Its fixes come down to closing the ways in:
- Where squirrels have chewed through siding into open space, cover the hole with thin galvanized sheet metal. The manual notes that squirrels can easily gnaw through aluminum.
- Remove limbs that overhang the roof or come within six feet of it, and trim trees and shrubs 18 to 24 inches back from the walls.
- Cap the fireplace chimney, and screen vent pipes with quarter-inch mesh or hardware cloth.
When is a squirrel in the attic worth a call?
When the noise has lasted more than a few days, when young are possible (for fox squirrels, most births fall in mid-March and July), or when the opening is high on the roofline and out of safe reach. When you call, describe when you hear the squirrel and where you think it gets in, and the conversation starts in the right place.
General information for Michigan homeowners, not legal advice. For Michigan’s rules on squirrels, see the DNR’s squirrels page.