The frequent observation of small branches or twigs clipped and dropped beneath trees is common in areas inhabited by squirrels. This behavior is not random but a deliberate activity necessary for the animal’s survival. Squirrels chew and strip branches to satisfy fundamental biological needs, including maintaining dental health, constructing shelter, and acquiring specific nutrients or moisture.
Maintaining Rodent Teeth
The most fundamental reason squirrels chew on hard materials like branches is the continuous growth of their incisor teeth. As rodents, squirrels possess upper and lower incisors that never stop growing throughout their lives. If these teeth are not constantly worn down, they will overgrow, potentially curving back into the animal’s mouth or skull.
Unchecked incisor growth can severely impact a squirrel’s ability to forage and eat, which would ultimately lead to starvation and other health complications. The act of gnawing on wood or nuts provides the necessary abrasion to keep these teeth at a functional, manageable length. Squirrel incisors feature a hard enamel layer on the front and softer dentin on the back, which naturally sharpens them into a chisel-like shape as they chew.
A squirrel’s incisors can grow several inches per year if unregulated. Chewing on tough materials such as tree bark and branches is a continuous practice, ensuring the animal can process the hard seeds and nuts that form the core of its diet. This mechanical process is primarily for filing the teeth.
Collecting Nesting Materials
Beyond dental maintenance, squirrels frequently chew off branches and small twigs as a specific step in constructing their nests, known as dreys. A drey is typically a spherical structure, often built high in the forks of tree branches, and it must be sturdy and well-insulated to protect the squirrel from weather and predators. The outer shell of the drey is primarily constructed from these freshly clipped, pliable twigs and branches.
Squirrels will often target small, leafy branches, which are easier to clip and transport to the nesting site. They use these clipped materials to weave a stable, dome-shaped framework, which is then reinforced with damp leaves and moss. The chewing of living branches may make the materials more manageable for weaving, as the slight moisture content allows for a tighter, more cohesive structure than brittle deadwood.
The selection of evergreen or deciduous materials depends on local availability and the time of year, with the overall goal being maximum camouflage and insulation. Squirrels may build multiple dreys throughout the year, including a flatter, lighter summer home and a more robust, insulated winter home, which necessitates the continuous gathering of these structural components. The numerous small branches found on the ground are often the rejected or excess building material from a squirrel’s ongoing construction project.
Seeking Water and Nutrients
A less obvious, yet highly important, reason for squirrels to chew on branches is to access essential nutritional resources. This behavior is most common during late winter and early spring when the animals’ typical food caches of nuts and seeds begin to deplete. At this time, squirrels strip away the outer bark to reach the cambium and phloem layers underneath.
The cambium layer is a thin, nutrient-rich tissue that transports water and sugars within the tree, and it offers a valuable source of minerals and carbohydrates when other food is scarce. This inner bark is often slightly sweet from the sap and can provide much-needed energy to the animals. The stripping of bark is a feeding behavior, distinguished from gnawing for dental wear, and often targets younger trees or branches with smoother, thinner bark.
Furthermore, some chewing is motivated by the need for hydration, as the inner layers of wood and fresh twigs contain moisture. Red squirrels, for example, are known to clip branches, particularly from maple trees, to access the sweet, sugary sap that flows during certain seasons. This consumption of cambium and sap is a seasonal survival strategy, providing both water and concentrated nutrients, including calcium.