Squirrels are common and active animals found in many backyards and natural spaces. Like all mammals, squirrels undergo a reproductive cycle that includes a period of gestation. This process involves the development of their young inside the mother’s body before birth.
Gestation Period
The gestation period for squirrels, the time from conception to birth, varies slightly among different species. For common species like the Eastern Gray Squirrel, the gestation period typically ranges from 40 to 45 days. Red squirrels have a slightly shorter gestation, usually between 36 and 42 days. The duration of gestation is a biological adaptation, with smaller animals often having shorter periods than larger ones, though exceptions exist. For instance, the approximately six-week gestation period for Eastern Gray Squirrels is a relatively quick developmental phase.
Breeding Seasons and Litter Size
Squirrels generally have two breeding seasons each year.
The first breeding period typically occurs in late winter or early spring, often from December to February in warmer climates, extending to March or May in colder regions. A second breeding season then takes place in mid-summer, usually from June to August.
Female squirrels are polyestrous, meaning they have multiple ovulation cycles annually, though they are receptive for only one day during each cycle.
While some female squirrels, especially younger ones, may only produce one litter per year, older and more experienced females can have two litters if food resources are abundant.
A typical litter size for squirrels ranges from two to four pups, but it can vary, with some litters having as many as seven or eight young.
Development of Pups
Squirrel pups are born in a helpless state. They are born hairless, blind, and deaf, weighing only about half an ounce.
Around three weeks of age, their ears open, and a thin layer of fur begins to appear. The pups’ eyes typically open around four to five weeks after birth.
This sensory development is a significant milestone, enabling them to begin exploring their immediate surroundings within the nest.
Around six to seven weeks old, the young squirrels start venturing outside the nest, often accompanied by their mother, to practice climbing and foraging skills. They are usually weaned and become independent between 10 to 12 weeks of age.