A squirrel’s nest, known as a drey, appears from the forest floor as a haphazard, messy ball of twigs and leaves, often mistaken for a bird’s nest. Closer inspection, however, reveals the structure to be a marvel of natural engineering, designed to provide shelter from harsh weather and predators. This arboreal home is not a simple pile of debris but a complex, multi-layered sphere with a carefully constructed interior that maximizes insulation and comfort.
Defining the Squirrel’s Home
Squirrels utilize two primary types of shelter: the constructed drey and the natural tree cavity, sometimes referred to as a den. Tree cavities are often preferred during the cold winter months because their wooden walls offer superior protection from wind and wet weather. The drey, however, is the home most commonly built by the squirrel itself, typically positioned high in a tree fork or close to the main trunk, which gives it a stable foundation. While both types of homes are lined with soft material, the drey is the focus here, representing the squirrel’s independent construction of a fully enclosed shelter, which can reach the approximate size of a football.
The Layered Architecture of the Drey
The squirrel drey is architecturally defined by three distinct structural layers, each serving a specific engineering purpose. The outermost shell consists of rough, interwoven twigs and small branches, creating a rigid, dome-like sphere. This external framework provides the structural integrity of the home, helping it resist wind and maintain its overall shape high up in the canopy.
Directly beneath this crude exterior lies a more densely packed middle layer, functioning as the drey’s insulation and moisture barrier. This layer is often constructed from pliable shoots, damp leaves, and tightly woven plant material. In some instances, flattened, dried leaves are layered like shingles, interlocking to shed rainwater and prevent moisture from penetrating the sheltered interior.
Finally, the innermost core is a compact, hollow sphere that forms the actual living chamber, often measuring between 9 to 20 centimeters in diameter. This central space is the most tightly woven part of the structure, where the squirrel can curl up. The density of the materials increases from the rough outer shell to this tight inner core, creating an effective pocket of still air that the squirrel’s body heat can efficiently warm.
Materials and Function of the Inner Chamber
The interior of the drey is lined with soft materials gathered solely for warmth, distinct from the structural elements of the outer layers. These lining materials can include soft grasses, shredded bark, pine needles, moss, and even scavenged items like animal fur or feathers. The squirrel tears and chews these materials into finer pieces, distributing them to create a plush, insulating bed.
The function of this soft lining is to stabilize the internal temperature, which is important for non-hibernating animals. When a squirrel is occupying its drey, the internal temperature can be maintained higher than the outside air, sometimes creating a differential of up to 30° Celsius in very cold weather. This temperature regulation is also important when the drey serves as a nursery, providing a stable, warm environment for the young.
What Else is Found Inside?
The drey’s interior is organized for the daily life of its resident. Pregnant females prepare the soft interior to give birth to and raise their kits. While squirrels are clean animals that drop most waste outside, the inner chamber may contain food items, though the bulk of the winter food supply is cached underground or in tree crevices elsewhere.
Access to the chamber is via one, or occasionally two, small openings, typically located near the bottom of the drey. These entrance holes are frequently oriented toward the tree trunk, which helps shield the interior from rain and wind. The small size of the opening also serves as a protective measure, helping the squirrel regulate the internal temperature while providing a narrow escape route from potential predators.