Squirrels are common in many environments, often building nests in trees. They construct nests primarily for shelter and to raise their young. Understanding their nesting behaviors provides insight into their adaptability and life cycles.
Key Nesting Periods
Squirrels exhibit two primary periods of intense nest building each year, tied to their reproductive cycles.
The first nesting season occurs from late winter to early spring (December to February). Females build secure nests for initial litters, protecting offspring from cold and predators.
A second significant nesting phase takes place from late summer to early fall (June to August) for a second litter. These nests are essential for young squirrels, offering a protected space where they can develop for approximately 10 to 12 weeks. A substantial boom in construction also occurs in the fall as squirrels prepare for the colder winter months.
Different Types of Squirrel Nests
Squirrels utilize two main types of nests: dreys and tree cavities.
A drey, the more commonly observed nest, is a spherical structure built from interwoven twigs, leaves, and other plant materials. These nests are typically found high in the forks of trees, often 20 to 45 feet above the ground, providing protection from ground predators. The exterior consists of branches and rough materials, while the interior is lined with softer elements such as moss, grass, and shredded bark for insulation and comfort.
Tree cavities, also known as dens, are another type of squirrel dwelling, often preferred for their enhanced security. These are natural hollows within tree trunks or large branches, which squirrels line with soft materials. Cavity nests offer superior protection from weather extremes and predators. Young squirrels born in dens may have a greater chance of survival compared to those born in dreys.
Factors Influencing Nest Construction
Beyond breeding seasons, environmental and behavioral factors influence when and how squirrels build nests.
Extreme weather conditions, such as cold snaps, can prompt squirrels to reinforce existing nests with additional insulating materials or to construct new, more robust shelters.
Squirrels may also build multiple nests within their territory (two to eight). These serve as backup options if a primary nest is disturbed or to escape parasites.
Availability of suitable nesting sites and food resources also plays a role. Squirrels build shelters close to reliable food sources for easy access, especially when raising young. The presence of predators can also lead to multiple nests, allowing mothers to relocate their young quickly if a threat arises.
Encountering a Squirrel Nest
Observing a squirrel nest is fascinating, but maintain respectful distance and avoid disturbance.
If a nest is found, especially one with young, leave it undisturbed. Squirrel mothers are attentive and generally return to care for their offspring.
If a baby squirrel appears distressed (injured or alone for an extended period), it may require assistance. Contact a local wildlife rehabilitation facility rather than intervening directly. Professionals have the expertise to assess the situation and provide appropriate care.