The sight of a squirrel carrying a large nut is common, sparking curiosity about their diet and preferences. These energetic rodents rely heavily on calorie-dense foods to fuel their active lifestyle, particularly in preparation for colder months. Walnuts are often observed as a high-priority item for these foragers. The safety and desirability of walnuts depend on the nut’s composition and the squirrel’s overall nutritional intake.
Walnut Appeal and Preference
Squirrels are strongly attracted to walnuts because they offer a significant energy reward. Walnuts, especially black walnuts, are rich in fats and proteins, providing the dense calories necessary for survival and winter preparation. This high caloric density makes the effort required to open the hard shell worthwhile.
Squirrels are opportunistic feeders but display a preference hierarchy. Walnuts are considered a high-value item, often chosen over less fatty seeds or nuts that offer a lower energy return. Their large size and distinct scent also contribute to their appeal, allowing squirrels to locate them quickly. Preference is often dependent on local availability, meaning a squirrel favors the most abundant high-calorie food in its environment.
Nutritional Content and Dietary Concerns
Walnuts are nutritionally rich, containing high levels of fat, protein, and phosphorus. However, mineral balance is more important than the quantity of any single nutrient. A major concern arises from the disproportionate ratio of calcium to phosphorus found in walnuts.
The ideal calcium-to-phosphorus ratio for a healthy squirrel diet is approximately 2:1. Walnuts, conversely, have a highly unfavorable ratio, sometimes as poor as 1:8.4, meaning they contain significantly more phosphorus than calcium. Excessive phosphorus intake inhibits the body’s ability to absorb calcium, which can lead to a condition known as Metabolic Bone Disease (MBD).
When a squirrel consumes too many walnuts or other high-phosphorus, low-calcium foods, its body must draw calcium directly from its bones to maintain necessary blood calcium levels. This leaching process weakens the skeletal structure, causing pain, fractures, and potentially paralysis. Therefore, while walnuts are safe as an occasional treat, they should never be a primary or regular food source provided by human feeding.
Caching and Consumption Behavior
The physical characteristics of the walnut dictate how squirrels interact with them for both immediate consumption and storage. Squirrels must first contend with the tough, fibrous husk before reaching the hard shell. The thick, rigid shell of the black walnut requires significant effort and powerful incisors to open.
A squirrel uses its strong teeth to gnaw along the shell’s seam or create a small hole, sometimes spending up to 40 minutes on a single nut to access the meat. Once secured, squirrels engage in scatter hoarding, burying individual walnuts in numerous shallow holes across a wide area. This strategy reduces the risk of losing their entire food store to a single competitor.
To retrieve hidden stores months later, squirrels utilize spatial memory and scent detection. While memory guides them back to the general area, their keen sense of smell allows them to pinpoint the exact location of the buried nut, even through snow and soil. Studies suggest that gray squirrels are highly successful, recovering an estimated 85% of their caches.