Bears, often perceived as large, powerful predators, exhibit a surprisingly diverse diet that extends beyond berries, fish, and larger game. Many bear species are opportunistic omnivores, meaning they consume both plant and animal matter, and a significant, though often overlooked, component of their diet includes various insects. These small creatures provide essential nutrients, especially when other food sources are scarce, highlighting the adaptability of bears in their natural habitats.
Bears and Their Insectivorous Tendencies
Many bear species across the globe readily consume insects. Brown bears, including grizzlies, frequently forage for insects, with some populations in Yellowstone National Park deriving a substantial portion of their annual food energy, sometimes up to 50%, from army cutworm moths. American black bears also incorporate insects like ants, beetles, and various larvae into their diet, contributing significantly to their protein intake in certain regions.
Sloth bears are highly specialized insectivores, with termites and ants forming the predominant part of their diet throughout the year, sometimes making up as much as 95% during non-fruiting seasons. These bears possess unique physical adaptations, such as long, curved claws and specialized muzzles, to efficiently extract their insect prey. Sun bears, the smallest bear species, are also notable insect eaters, consuming termites, beetles, and bee larvae, which serve as a significant protein source in their tropical forest environments. Even spectacled bears, primarily herbivorous, supplement their plant-based diet with insects. The extent of insect consumption varies widely among species and geographic locations, often depending on the seasonal availability of other preferred foods.
Common Insect Prey
Bears target a variety of insects, with ants being a particularly common and important food source for many species. Black bears, brown bears, and sloth bears often seek out ant colonies to consume the protein- and fat-rich larvae and pupae, referred to as “brood.” They use their sticky tongues to efficiently collect these tiny morsels from nests.
Termites are another staple, especially for sloth bears, who use their powerful claws to break open the hard, cement-like mounds to access the insects within. Sun bears also forage for termites, tearing into logs and mounds. Beetle larvae, commonly known as grubs, are found by bears digging through rotting wood or soil and are consumed by black bears, brown bears, and sun bears.
Brown bears, particularly grizzlies in areas like Yellowstone, consume large quantities of army cutworm moths, sometimes eating tens of thousands in a single day. Bears also target bees and wasps for their protein-packed larvae and adult insects. Bears employ various foraging techniques to access these insects, including digging, ripping apart logs and stumps, and turning over rocks.
The Nutritional Value of Insects for Bears
Insects serve as a valuable nutritional component in a bear’s diet, offering concentrated sources of vital macronutrients. They are notably rich in protein, with some insects containing up to 80-90% protein, significantly higher than many other food sources. Insects also provide essential fats, vitamins, and minerals that contribute to a bear’s overall health.
Insects become important supplementary sources during specific seasons. In spring, after emerging from hibernation, or during periods when other primary foods like berries or fish are scarce, insects offer a reliable energy boost. The fat and protein derived from insects are crucial for various biological processes, including supporting growth in young bears, aiding in reproduction, and building the substantial fat reserves necessary for hibernation. Brown bears preparing for winter consume many calories daily, and insects contribute to this feeding period.