Squirrels are commonly observed animals in many environments, from forests to urban backyards. These agile rodents require secure places for shelter and raising their young. Understanding their nesting habits provides insight into their behavior and aids in human-wildlife coexistence.
Understanding Squirrel Nests
Squirrels construct two main types of nests: dreys and cavity nests. A drey is a spherical nest built in tree branches, typically appearing as a messy ball of leaves and twigs. The outer shell is woven from twigs, leaves, and moss. The inner chamber, about 6 to 8 inches in diameter, is lined with softer materials like shredded bark, grass, moss, feathers, and pine needles for insulation. Dreys can range from 10 to 30 inches in diameter.
Cavity nests, also known as dens, are found within natural tree hollows or abandoned spaces in tree trunks. These natural cavities can form through decay or may be old woodpecker holes that squirrels enlarge by gnawing the entrance. Cavity nests offer superior protection from rain, wind, and snow compared to dreys. Squirrels line these hollows with soft materials, similar to those used in dreys, to create a protected space.
Natural Nesting Habitats
In natural settings, squirrels primarily build their nests high within trees. Dreys are often constructed in the forks of large tree branches or close to the main trunk, providing stability and support. These nests are typically found at least 20 feet (6 meters) above the ground. The elevated position and dense foliage offer concealment and protection from ground predators.
Squirrels show preferences for certain tree species for nesting. Eastern gray squirrels, for instance, favor deciduous trees like oak, hickory, maple, elm, and beech, which also provide abundant food sources. Red squirrels may build dreys in conifers. Beyond dreys, squirrels also utilize natural tree cavities found in old, large trees where decay has created hollows. Some species, like fox squirrels, will nest in tree cavities if the entrance is small enough to deter predators.
Nesting in Human Environments
Squirrels often adapt to human-populated areas, seeking shelter in and around man-made structures. Common nesting locations include attics, chimneys, garages, and sheds. They may also access spaces within eaves, wall voids, and roof vents. These areas provide warmth, security, and protection from the elements.
Signs of squirrels nesting in human environments include rustling, scampering, or scratching sounds. Visible entry points, such as small holes chewed into soffits, fascia boards, or vents, are another indicator. Gnaw marks on wood, wires, or exterior materials, as well as the presence of droppings or a musty odor, can also signal a squirrel presence. Squirrels only need a gap of about 1.5 inches to gain entry into a structure.
Factors Influencing Nest Site Selection
Squirrels select nesting sites based on several factors that promote their survival and the successful rearing of their young. A primary consideration is protection from predators, which is why nests are often located high in trees or within enclosed spaces. The elevated height of dreys, often in the thinner branches near the top, helps deter predators like raccoons and opossums.
Shelter from harsh weather conditions, including cold, rain, and wind, is another significant factor. Cavity nests offer superior insulation and protection during cold weather, leading squirrels to prefer them in winter. When natural cavities are unavailable, dreys are built with thick, interwoven layers of leaves and twigs that create insulated air pockets.
Proximity to reliable food and water sources also influences nest placement. Squirrels choose locations that offer easy access to their varied diet, including nuts, seeds, and plant materials. Nests also serve as safe places for raising young. Squirrels may build multiple nests, using secondary sites as alternative resting spots.