The term “brown squirrel” often refers to the two most widespread tree squirrels in North America: the Eastern Gray Squirrel (Sciurus carolinensis) and the Fox Squirrel (Sciurus niger). Despite its name, the Eastern Gray Squirrel frequently has brown streaks, giving it a brown-gray appearance. The Fox Squirrel is often a distinct reddish-yellow or rufous color, which is a clear shade of brown. This article focuses on the geographic distribution and nesting habits of these two species.
Identifying the Most Common Brown Squirrels and Their Primary Geographic Ranges
The Eastern Gray Squirrel is native to the eastern half of the United States, extending from southern Canada down to Florida and west to Texas and the Mississippi River valley. This highly adaptable species has also been introduced to localized areas in the Western United States, including parts of Washington and California, and is established in parts of Europe.
The Fox Squirrel is the largest native tree squirrel in North America, covering much of the eastern and central United States. Its range extends further west than the gray squirrel’s, reaching into the Dakotas, Colorado, and Texas, and north into parts of Canada. This species has the most variable coloration of any North American squirrel, ranging from reddish-brown to dark gray or black. Introduced populations also exist in urban and suburban areas across the Western United States.
The ranges of these two species overlap throughout the Eastern and Midwestern United States. The Eastern Gray Squirrel dominates in areas with dense, continuous canopy cover, such as large, mature forests. The Fox Squirrel is more successful in open woodlands, forest edges, and areas where trees are scattered. These differing habitat preferences help minimize direct competition where both species are present.
Preferred Habitats and Local Environment Requirements
Squirrels require a consistent food supply and mature trees for safety and shelter. The preferred environment for both species is a deciduous or mixed forest, rich in nut-producing trees like oaks, hickories, and walnuts. The availability of nuts dictates where a squirrel population can thrive and sustain itself through colder months.
The Eastern Gray Squirrel typically seeks mature, continuous hardwood forests with a closed canopy, allowing easy travel between trees. Their agility provides defense against predators. These squirrels also successfully colonize urban and suburban environments, utilizing parks and tree-lined residential areas.
The Fox Squirrel is slightly larger and less agile in dense canopies, so it is often found in open forest stands or woodlots with less understory. This species tolerates fragmented habitats and spends more time foraging on the ground. They are often found in riparian corridors and small patches of trees near agricultural or prairie regions, flourishing in areas the gray squirrel might avoid.
Shelter and Nesting Locations
Squirrels use two distinct types of structures for shelter and raising their young: the drey and the tree cavity. The drey is a bulky, spherical nest built externally in tree branches. Dreys are constructed from interwoven twigs and leaves, forming a rough outer shell lined with softer materials like moss, grass, or shredded bark.
These leaf nests are typically built in the fork of a branch or near the trunk, often 20 to 40 feet above the ground. They are used seasonally, particularly during warmer months, and can be constructed quickly. In colder weather, dreys are less insulated and are sometimes shared by multiple squirrels for warmth.
The preferred and more permanent shelter is a tree cavity. These dens are located inside hollow trunks, large branches, or old woodpecker holes, providing superior insulation and protection from severe weather and predators. Cavity dens are important for surviving winter and for rearing the two annual litters of young. If natural cavities are scarce, squirrels may use human structures, such as attics or eaves, seeking similar warm spaces.