A squirrel nest, known as a drey, is a specialized shelter constructed by tree squirrels to survive the elements and raise their young. Squirrels adapt their building methods based on the environment, available materials, and the season. Identifying these distinct structures involves understanding the two main forms of shelter squirrels utilize. This knowledge helps in recognizing squirrel activity high up in the tree canopy.
The Two Primary Nest Types
Squirrels primarily rely on two distinct types of shelter: the external drey and the internal cavity nest. The drey is the most commonly observed structure, consisting of a large, visible ball of leaves and twigs built high in tree branches. This nest is constructed entirely by the squirrel from gathered materials.
In contrast, the cavity nest, sometimes called a den, utilizes an existing void, often a natural tree hollow formed by decay or an abandoned woodpecker hole. Squirrels favor these internal spaces during periods of extreme cold because the surrounding wood provides superior insulation. The cavity nest is appropriated and lined with soft materials like shredded bark and moss for comfort.
Identifying the External Nest (The Drey)
The external squirrel drey is a large, bulky structure that often appears somewhat messy, unlike the neater, cup-shaped nests of most birds. Dreys are spherical or oval, typically reaching the size of a basketball, or about 12 to 24 inches in diameter. They are built using a framework of interwoven twigs and small branches.
This framework is stuffed and covered with a thick layer of dry leaves, moss, and bark to create insulation and water resistance. The completed structure is enclosed, resembling a dense, leaf-covered ball, with a small entrance hole usually tucked toward the tree trunk for easier access and defense.
For stability and protection, squirrels generally place their dreys in the sturdy fork of a large branch or close to the main trunk, often 20 feet or higher above the ground. An active drey is usually dense and well-maintained with fresh material, while an older, abandoned one may look dilapidated and thin.
Why Nests are Constructed and Used
Squirrel nests serve multiple purposes, acting as a refuge from severe weather and a secure location for reproduction. The structure offers protection from predators that cannot easily access the elevated, enclosed space. Female squirrels use these nests as nurseries, raising their young, who typically remain in the safety of the nest for 10 to 12 weeks.
Nest construction varies based on the season, reflecting its primary function. Summer dreys are sometimes looser and less insulated, providing a temporary resting spot or a cooler retreat from heat. Winter nests are heavily fortified and lined with finer materials like shredded bark and fur to maximize thermal regulation, as squirrels remain active year-round. Squirrels frequently maintain several nests within their territory, using these secondary shelters as temporary rest stops or reserve housing if their main home is disturbed.