The answer to whether rats build nests in trees is yes, but this behavior depends almost entirely on the specific rat species involved. The two most common types of commensal rats, the Roof Rat and the Norway Rat, exhibit dramatically different nesting preferences that determine if a tree is a suitable home. Understanding this distinction helps identify which type of rodent might be present in a given area.
The Arboreal Dweller: Roof Rat Nesting
The species that frequently nests in elevated positions, including trees, is the Roof Rat (Rattus rattus), also known as the black rat or ship rat. This species is naturally arboreal, meaning it is an agile climber with a preference for high places, which offers safety from predators and direct access to food sources, such as fruit trees. They use their climbing ability to travel easily along vines, utility lines, and upper branches.
A Roof Rat’s nest is typically a messy, spherical structure built in dense vegetation or the upper parts of structures. They gather materials like leaves, small twigs, shredded paper, and other fibrous debris to construct these nests. Preferred outdoor nesting sites include dense, non-deciduous trees, thick vines, and the crowns of palm trees, where old, hanging fronds provide cover.
The selection of a tree is often linked to available food, with citrus and nut trees being attractive sites for nesting. Since Roof Rats are omnivores, nesting directly in a food source minimizes travel and exposure. They also use hollow tree cavities for shelter, demonstrating a strong preference for elevated, protected spaces for raising their litters.
The Ground Dweller: Norway Rat Nesting
In contrast to their arboreal relatives, the Norway Rat (Rattus norvegicus), also called the brown rat or sewer rat, is predominantly a ground dweller. This species prefers subterranean environments and constructs elaborate burrow systems. Norway Rats dig their nests in burrows below ground or at ground level, often along foundations, under concrete slabs, or in dense ground cover.
Their extensive burrows can reach lengths of up to 6.5 feet, often featuring multiple entrances and a hidden escape route. Nests within these burrows are lined with shredded materials such as paper, cloth, or insulation. While Norway Rats are capable of climbing, they rarely establish their primary nests in trees.
Norway Rats prefer to live in close association with human activity, nesting near sources of warmth, food, and water, such as sewers, basements, and under storage piles. Their ground-level habits mean that if a nest is found in a tree, it is highly improbable that the inhabitant is a Norway Rat. The presence of Norway Rats is indicated by burrow openings, which are two to four inches wide, found in the soil.
Distinguishing Tree Nests and Signs of Infestation
When a nest is spotted high in a tree, it must be distinguished from a squirrel’s nest, which is also constructed of leaves and twigs. Rat nests tend to be smaller, messier, and often concealed deep within the thickest part of the foliage, especially in trees bearing fruit or nuts. Squirrel nests, by comparison, are larger, more structured, and often built in a more exposed fork of a branch.
Other signs confirm a rat presence in the area, regardless of the nest’s location. Since rats are nocturnal, scratching or scurrying noises in an attic or walls after dusk indicate activity. Outside, look for smooth, dark, greasy smudge marks, or “runways,” left along walls or rafters where the rat’s oily fur rubs against surfaces during repeated travel.
The presence of droppings is another key indicator, as rats tend to leave their cylindrical, dark droppings scattered along their established travel paths. Gnaw marks on wood, wires, or even hollowed-out fruit hanging on a tree are physical evidence of feeding and movement. These signs confirm a rat infestation.