Grey squirrels, familiar inhabitants of many wooded areas, parks, and suburban gardens, are a widespread and adaptable species. These active rodents are commonly observed foraging during daylight hours across North America and in regions where they have been introduced.
Key Mating Periods
Grey squirrels typically engage in mating activities during two distinct periods each year. The first breeding season commences in late winter, generally spanning from December to February. Following this initial period, a second mating season occurs in mid-summer, usually between May and June. These two periods represent the primary times when female squirrels are receptive to mating.
During these key times, female squirrels are receptive for a short window, often just one day within their cycle. This brief receptivity triggers a behavior known as a “mating chase,” where multiple male squirrels actively pursue a single female through trees and across the ground. These chases are a characteristic part of their reproductive cycle, demonstrating the competition among males for mating opportunities.
Influences on Breeding Timing
Several environmental and biological factors can influence the precise timing and success of grey squirrel breeding. The availability of food, particularly mast crops such as acorns and hickory nuts, plays a role in their reproductive output. Years with abundant food resources often correlate with a higher number of females successfully producing two litters.
Weather conditions, including temperature and snow cover, can also shift when breeding begins or its intensity. Prolonged harsh winter conditions might affect overall squirrel health and, consequently, their breeding readiness. While not directly dictating the mating periods, these factors contribute to the overall reproductive success and timing within a given year.
From Mating to Offspring
Following successful mating, the female grey squirrel undergoes a gestation period that lasts between 40 and 45 days. She prepares a nest, often a drey made of leaves and twigs high in a tree or within a tree cavity, where she will give birth. The young, referred to as pups or kits, are born blind, hairless, and completely dependent on their mother.
Litter sizes range from two to six young, though a female can give birth to as many as eight or nine. The first litters of the year are born in March or April, corresponding to the late winter mating period, while second litters arrive in July or August. The young are weaned around 10 to 12 weeks of age and begin to explore outside the nest shortly thereafter. Adult female squirrels are capable of producing one or two litters annually.