March marks a biologically significant transition in the annual rhythm of tree squirrels in Ontario. Although air temperatures may still be cool and snow cover persists in parts of the region, daylight increases and physiological processes that drive breeding and nesting behaviour are already underway.
This article—compliant with Micro Layer principles—explains what changes in squirrel behaviour typically occur in March in Toronto’s urban ecosystem, without offering treatment guidance or actionable removal advice.
Squirrels Are Active Throughout the Year
Unlike true hibernators, tree squirrels do not enter deep dormancy during winter. They remain active year-round, although daily movement and visible foraging can be reduced during the coldest periods. As daylight increases through late winter, activity patterns shift toward behaviours related to reproduction and territory maintenance rather than purely survival-driven routines.
Eastern gray squirrels are one of the most common species in the Toronto region and exhibit behavioural plasticity that allows them to respond quickly to seasonal cues. They do not hibernate, even in cold conditions; instead they adjust activity while relying on stored caches and shelter.
March as a Transitional Month
March falls at the cusp of the first breeding cycle for many squirrels:
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In Ontario, the first breeding season generally begins in late winter to early spring, with mating behaviour typically occurring during the period that overlaps December through February. Because gestation for eastern gray squirrels lasts roughly 40–44 days, offspring from late winter breeding are usually born in late winter or early spring—often around March.
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This means that March corresponds with peak activity related to young squirrels (kits) being born and early nesting behaviour for spring litters, even if late winter weather still persists.
These seasonal rhythms are shaped by daylight length, physiological readiness to breed, and temperature cues rather than calendar date alone.
Nesting Behaviour Begins to Intensify
During this early spring window, female squirrels may:
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strengthen or renovate existing nests (dreys)
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choose sheltered tree cavities or alternative elevated shelter sites
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prepare spaces in anticipation of or during early maternal care
Because resident squirrels are already physiologically engaged in reproductive activities, structures that offer stable micro-climates—such as roof cavities or insulated spaces—may begin to attract increased seasonal attention.
This is consistent with wildlife rehabilitation observations that squirrels found in attic spaces early in the season are often assumed to be mothers with dependent young.
Increased Overall Movement
Male squirrels and juveniles emerging from winter-conditioned sites often display:
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broader exploratory behaviour
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more frequent territorial chasing
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increased locomotion across tree canopies
These behaviours do not necessarily indicate novel entry into built structures; rather, they reflect the natural ramp-up of activity following winter’s lower-mobility period.
Not a Singular “Start” Date
It is important to understand that March is not a singular threshold where squirrels suddenly appear, but a period in which seasonal biological processes are synchronizing across the population:
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Gestation from late-winter mating leads to births
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Daylight length cues increased appetite and movement
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Territory dynamics shift with hormonal influences
This explains why patterns of squirrel activity in March can appear more noticeable—even if the animals have been present in the local ecosystem throughout winter.
Spring and Urban Ecology
March represents a bridge between winter energy conservation and spring reproductive investment in squirrels. Changes in behaviour are ecological and rhythmic. Urban contexts such as Toronto amplify these rhythms because:
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tree canopy, parks, and yards provide reliable food sources
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built elements offer supplemental shelter opportunities
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temperature moderation in built environments can shape micro-habitat selection
Perspective
March is not a month of sudden squirrel “arrival”—it is a phase in a continuous annual cycle of activity. Spring movement and behaviour reflect biological imperatives, not arbitrary appearance. This seasonal context helps explain observed patterns of urban squirrel behaviour without implying intentional or random entry.