Squirrels breed twice a year: a late-winter season running roughly February through April, and a midsummer season running roughly July through September. Litters usually hold two to four young. Kits are born blind and hairless, open their eyes around four weeks, and leave the nest at ten to twelve weeks. If you keep a nest box in your yard, the practical takeaway is timing: leave it closed during both breeding windows and do your maintenance in late autumn instead.
Two breeding seasons a year
Eastern grey squirrels, the species most common in backyards across the US, typically breed twice annually. The first window falls in late winter, roughly February to April, and the second arrives in midsummer, roughly July to September. Timing shifts somewhat with latitude and food availability from one year to the next, but the two-season pattern holds across most of their range.
Not every female breeds in both windows, and not every population does — food supply, density, and regional climate all play a role. But if you're watching activity around a nest box or tree cavity, February to April and July to September are the two stretches to have on your radar.
How many babies do squirrels have?
A typical litter runs two to four kits, occasionally more. Females den up alone to give birth and raise the litter without a male present — a single mother handles the entire rearing period. Kits are born blind, hairless, and completely dependent on her for warmth, milk, and protection. There's no visible sign from outside a nest box that a litter has arrived, which is exactly why late-season disturbance is the thing to avoid — more on that below.
From newborn to independent: a development timeline
Development follows a fairly predictable arc. Here's roughly what happens, week by week:
- Birth: Kits are blind, hairless, and fully dependent on the mother for heat and milk.
- Around 3 weeks: Fur starts coming in.
- Around 4 weeks: Eyes open.
- 6 to 8 weeks: Kits begin exploring near the nest entrance and start sampling solid food.
- 10 to 12 weeks: Weaning is largely complete and young squirrels begin leaving the nest for good.
By three months, most kits are foraging independently, though some stay loosely associated with the mother's territory into their first winter.
Red and fox squirrels: a similar pattern, with regional variation
Red squirrels and fox squirrels generally follow the same two-season structure, though the exact months shift with climate and latitude — populations further north or at higher elevation tend to compress activity into a narrower window. Litter size and the blind-hairless-to-weaned progression track closely with what's described above for grey squirrels. If you're setting up a habitat and want to attract a specific species to your yard, our guide on how to attract squirrels to your backyard covers placement and feeding choices that matter by region.
Why nest box timing matters more than most people think
This is the part worth building a habit around: don't open, clean, or move a squirrel nest box during either breeding window. A female with a young litter that gets disturbed may relocate the kits before they're ready, abandon the nest entirely, or in worse cases lose kits to exposure or a fall. Even a quiet check that seems harmless — lifting the lid to look, tapping the side, moving the box a few feet — can be enough to trigger that response.
The safe window for cleaning out a nest box, checking hardware, or doing general upkeep is late autumn, after the second breeding season has wound down and before the first one starts up again. If you're due for a check this year, that's your slot. Our squirrel house guide walks through what a proper autumn clean-out involves and how to set the habitat up for the seasons ahead.
Found a fallen kit? Here's what to do
Young squirrels sometimes end up on the ground — a nest disturbance, a storm, a branch that gave way. If you find one:
- Check if the mother is nearby first. If the kit is uninjured and the area is safe, place it in a shallow, warm container near the base of the tree and step back. Mothers will often retrieve a kit within a few hours, especially at dusk or dawn.
- Keep pets and people away from the area while you give her that chance.
- If she doesn't return, or the kit is injured, cold, or clearly too young to have fur, contact a licensed wildlife rehabilitator right away. They're equipped to assess and care for the animal correctly — this isn't something to take on yourself. A search for “wildlife rehabilitator” plus your state or county will usually turn up a local contact, or your state wildlife agency can point you to one.
Don't attempt to feed, warm with direct heat, or raise a wild kit at home — even with good intentions, it's easy to cause harm, and young squirrels raised without their mother often don't develop the skills they need later. A rehabilitator is the right call every time.
Setting your yard up for the year ahead
If squirrels are already denning in your yard, or you're hoping to give them a reason to, the habitat itself matters less than what surrounds it. Pairing a nest box with a steady, appropriate food source makes a real difference — see what to feed squirrels year-round for a season-by-season breakdown. And if you're deciding between a standalone feeder and a nesting habitat, our comparison of a squirrel house vs. squirrel feeder lays out what each one actually does.
For yards that want both in one place, the cedar Squirrel House Hideout Feeder combines a nesting chamber with a built-in feeding station — one habitat, minimal footprint, and the same autumn-only maintenance rule applies.
Whatever setup you choose, the biggest thing you can do for a resident squirrel family this year is also the easiest to remember: know the two breeding windows, and let the box alone until autumn.
