Tree squirrels are a familiar sight in parks and forests, spending most of their lives navigating the upper canopy. These agile, arboreal mammals rely on trees for food, safety, and shelter. A common observation is the large, messy-looking clump of leaves and twigs lodged high in the branches. The answer is yes, tree squirrels actively construct their own homes in the branches, which are used for resting, hiding from predators, and raising their young. This practice is a fundamental part of their survival strategy.
Defining the Squirrel’s Tree Nest
The structure that a squirrel builds in the tree canopy is known as a drey. This is the most visible type of shelter they create, often appearing as a bulky, spherical mass of vegetation nestled against the tree trunk or securely placed in a major branch fork. Dreys are usually built high above the ground, often situated between 20 and 45 feet up, taking advantage of the natural support offered by the tree’s structure. The overall size of a drey frequently resembles that of a football, with a diameter that can easily exceed one foot. Dreys are sometimes mistaken for bird nests, but their fully enclosed, shaggy appearance and dense composition set them apart from the open-cup structure characteristic of most large bird species.
The Engineering of a Squirrel Drey
The construction of a drey results in a functional and weather-resistant shelter. The outer layer is composed of sturdier materials, primarily densely woven, pliable twigs, small branches, and leafy matter. Squirrels gnaw these branches off the tree and weave them together to form a robust structural shell that protects the interior from wind and rain.
Inside this protective shell, the squirrel creates a hollow core, which it lines with a thick layer of soft, insulating material. This inner lining often consists of shredded bark, dried leaves, moss, grass, or animal fur to ensure warmth and comfort. The completed structure is a double-walled chamber, with the outer layer providing defense and the inner layer focusing on thermal regulation. The squirrel incorporates a small, concealed entrance hole, usually placed low and flush with the tree branch, which helps maintain the interior temperature and deter intruders.
When Squirrels Choose Natural Cavities
Dreys represent only one of two primary shelter options for tree squirrels. Squirrels frequently seek out natural tree cavities, referred to as dens, for more permanent residence. These dens are naturally occurring hollows inside tree trunks or large, decaying branches, sometimes originating from abandoned woodpecker holes or areas of natural wood decay.
The hard wood surrounding a cavity den provides superior protection from severe weather conditions, including heavy rain, high winds, and extreme cold. Squirrels prefer these insulated dens for overwintering because they offer better thermal stability than an exposed drey. Tree cavities are also the preferred location for raising young, as the enhanced physical protection and stable temperature significantly increase the survival rate of litters. Squirrels often maintain multiple dreys and dens within their territory, using the built dreys as convenient, temporary resting spots during warmer months and reserving the more secure dens for the rigors of winter and reproduction.