Squirrel diets are highly adaptable, shifting significantly with the seasons. Summer provides a flush of resources, enabling a much broader and more energy-rich diet than the lean winter months. This period of abundance allows these opportunistic foragers to consume a wide variety of items, fueling their active lifestyle and preparing for the future.
Summer Staples: Nuts, Seeds, and Fungi
Summer is the period when many high-calorie tree resources first become available, even before they fully mature. Squirrels actively seek out immature or “green” nuts, such as walnuts, pecans, and hickory nuts, which are soft enough to chew through the tough outer husk and developing shell. While these lack the full nutritional concentration of dried nuts, they offer immediate energy and are easier to process than hardened winter stores. Acorns are also consumed in their green stage, providing a carbohydrate-rich food source for immediate metabolic needs.
Tree seeds also form a significant portion of the summer intake before the main autumn seed drop. They consume the winged seeds of maple trees, known as samaras, which are readily available as the trees release them. Conifer seeds, extracted from pine cones, are a consistent source of fat and protein that squirrels access throughout the warmer months. This high-energy plant matter supports the intense activity levels required for daily foraging, territory defense, and early caching.
Fungi, including various species of mushrooms and hypogeous truffles, become more prevalent in the humid summer environment and are readily incorporated into the diet. Squirrels sometimes dry mushrooms by placing them on tree branches to reduce moisture content before storing them in caches. These fungi provide essential nitrogen, phosphorus, and minerals, supplementing the primary nut and seed intake.
Protein Sources and Opportunistic Foraging
Squirrels are omnivores, and summer is a key time to supplement their largely plant-based diet with concentrated protein and calcium. They actively forage for insects, including beetle larvae, caterpillars, and various ground-dwelling arthropods. This animal matter is important for nursing females who require extra nutrients for milk production and for rapidly growing juveniles. Consuming insects helps balance the high-fat, low-calcium content of their primary seed diet.
Non-plant food sources can extend to vertebrate prey, though this is primarily opportunistic rather than routine hunting. Tree squirrels may raid bird nests for eggs and nestlings, and some ground squirrel species have been documented hunting small rodents like voles during population booms. Near human habitation, squirrels display scavenging behavior, consuming discarded food scraps or carrion to access fat and minerals often limited in a purely herbivorous diet.
The consumption of non-plant items is often driven by a need for minerals, especially calcium, which is necessary for bone health and proper tooth development. To meet this need, squirrels have been observed chewing on discarded bones, antlers, or snail shells.
Water-Rich Foods and Hydration
The need for hydration increases significantly during high summer temperatures, driving squirrels to seek out moisture-rich foods. Wild fruits and berries, such as blackberries, raspberries, and wild grapes, are sought out for their sugar content and their high water volume. The consumption of these juicy items helps to offset water loss from activity and heat.
Cultivated garden produce, including tomatoes, watermelons, and melons, are often targeted by squirrels for their liquid content during dry spells. In urban and suburban settings, this pursuit of hydration can lead to damage in vegetable gardens. When external water sources are limited, squirrels rely on the moisture from these foods to maintain internal balance.
Direct water consumption remains necessary, especially in arid or hot conditions, despite moisture gained from diet. Squirrels utilize natural sources like puddles, streams, and morning dew on leaves. In residential areas, they visit artificial sources, including bird baths or pet water dishes.