Yes, squirrels can indeed open walnuts. Their ability to access the nutritious kernels within such hard shells is due to remarkable biological adaptations and persistent behavior. They possess specialized tools and techniques to overcome the challenge of a walnut’s formidable exterior.
The Squirrel’s Tool Kit
Squirrels are equipped with specific biological features that make them expert nutcrackers. Their most prominent tools are their four chisel-shaped incisors, two on the upper jaw and two on the lower. These incisors grow continuously, at approximately 14 centimeters per year. This continuous growth is crucial as constant gnawing wears them down, ensuring they always have sharp, effective cutting edges.
Behind these incisors, squirrels have a gap called a diastema, followed by premolars and molars; however, the incisors perform the initial breaking. Their lower jaw is uniquely designed with two separate bones, connected by a ligament, allowing flexible side-to-side movement of the incisors for various gnawing tasks. Squirrels also possess powerful jaw muscles, like the masseter, which generate significant force to crack open hard shells. Their skull structure provides leverage and helps absorb the shock of biting down on tough surfaces.
Mastering the Walnut
Squirrels employ a precise, learned technique to open walnuts, utilizing more than just anatomical advantages. They begin by holding the walnut securely with their dexterous front paws, essential for manipulating the nut and finding its weakest points. Often, they target the natural seams of the walnut shell where the two halves meet. They may also rotate the nut, testing different spots to find a purchase point.
Once a weak spot is identified, the squirrel uses its sharp incisors to gnaw a groove or small hole into the shell. This gnawing can be a prolonged process, sometimes taking over 40 minutes for especially tough black walnuts. For particularly hard nuts like black walnuts, squirrels might also drop them from trees onto hard surfaces or even bury them in soil to allow decomposition to weaken the shell before retrieval.
In contrast, English walnuts are generally easier to crack. The squirrel then uses its incisors to pry or split the shell open, leveraging the initial groove. The dexterity of their paws allows them to carefully extract the kernel without damaging it.
Why Walnuts are Worth the Effort
Walnuts represent a high-value food source for squirrels, making the effort of opening them worthwhile. These nuts are rich in healthy fats, proteins, and essential vitamins and minerals, providing dense energy crucial for their active lifestyle. The fats contribute to their overall health and fur condition.
Squirrels often consume walnuts immediately, but they also engage in caching behavior, burying nuts for future consumption. This is important for preparing for colder months when other food sources become scarce. Eastern gray squirrels, for example, are known as “scatter hoarders,” burying individual nuts in various locations, relying on their keen sense of smell and spatial memory to retrieve them later.