A drey is the common term for a tree squirrel’s nest, a specially constructed shelter found high in tree branches and built by various tree squirrel species like Eastern Gray, Red, and Flying Squirrels. Dreys serve as primary residences, offering protection and a place to rest throughout the year.
Anatomy of a Squirrel Drey
A squirrel drey is typically a spherical structure, often appearing as a messy ball of leaves and twigs. Its outer shell consists of interwoven twigs and branches, forming a robust framework. Squirrels gather a variety of natural materials for construction, including green twigs, dry leaves, moss, grass, and shredded bark.
The interior of a drey is meticulously lined with finer, softer materials such as moss, pine needles, feathers, and fur, providing insulation and comfort and making the drey significantly warmer than the outside air. Dreys typically have one or two entrance holes, often positioned near the trunk to keep out rain and provide an escape route. These nests are usually located high in trees, often 6 to 13 meters (20 to 42 feet) or more above the ground, nestled in a tree crotch or against the main trunk for stability.
Why Squirrels Build Dreys
Squirrels construct dreys for shelter from environmental challenges. These nests protect from harsh weather, including rain, snow, and strong winds. Dense construction insulates squirrels from extreme temperatures, allowing them to remain active even in winter.
Dreys also defend against predators, offering a safe, elevated refuge from ground hunters. Their high placement in trees, often near the trunk, makes them less accessible to threats. Dreys are essential for reproduction, providing a secure location for females to give birth and raise young. Females typically nest alone when pregnant and will move their young if the drey is disturbed.
Dreys Compared to Dens
Squirrels use two main types of shelters: dreys and dens. A drey is an external, constructed nest in tree branches. In contrast, a den is a cavity or hollow within a tree trunk or large branch, often originating from abandoned woodpecker holes or natural decay.
Dens generally offer more permanent and robust shelter than dreys, providing superior insulation and predator protection. Squirrels often prefer dens for overwintering or raising young, especially during colder months, due to their enhanced security and warmth. However, if suitable tree cavities are scarce, squirrels rely on dreys, sometimes congregating for warmth during severe cold. While dreys are built, dens are adapted from existing tree features, with squirrels sometimes gnawing to enlarge entrance holes.