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hyperphagia

Black Bears Raiding Brood

11-1-17 bear binging 049A7147Previously this fall I posted about Black Bears foraging ferociously in the fall in order to store fat (sometimes doubling their weight) before hibernating. That post showed an ant-infested tree that had been ripped apart. As winter approaches, signs of bears’ frenetic gorging (hyperphagia) increase dramatically. Protein-rich sources such as Bald-faced Hornet nests (suspended from branches) and Yellow Jacket nests (in cavities in the ground) are highly sought after.

If you look closely, you’ll see that the claws of the bear that attempted to raid the hornet nest (suspended ten feet above the ground) were able to reach just the bottom portion of the nest, tearing the outer multi-layered, paper envelope but not reaching the brood-containing cells within. The Yellow Jacket cells containing brood (eggs, larvae and pupae), on the other hand, were all removed from the ground nest and consumed. All that remains is a portion of the outer envelope and a few adults.

 

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Black Bears Foraging

9-4-17 bear tree2 049A4107

This is the time of year when Black Bears are looking for every available source of food in order to bulk up before entering hibernation. During this period of gorging (hyperphagia) Black Bears consume large quantities of fruits, berries, nuts, grasses, roots and insects.

In particular, they favor the brood (larvae and pupae) of ants, due to their relatively high content of fat and protein. Black Bears find brood by detecting the pheromones and other chemicals such as formic acid that ants use for communication and defense. Research has confirmed that Black Bears will dig up as many as 200 ant colonies a day, flipping rocks, moss and leaf litter over and tearing apart logs, stumps and snags (such as the one pictured), using their canine teeth and claws to gain access to the ants. Once they have torn apart the stump or snag, they use their long, sticky tongues to gather brood. Anthills are avoided except for when Black Bears are extremely hungry, due to the fact that bears prefer not to get a lot of soil or sand mixed in with the brood they’re eating. (Thanks to Virginia Barlow for photo op.)


Black Bears Gorging

10-28-16-corn-203Black bears are omnivores as well as opportunists.  They will eat almost anything that they can find, but the majority of their diet consists of grasses, roots, berries, nuts and insects (particularly the larvae).  As the days cool, and the time for hibernation nears, black bears enter a stage called “hyperphagia,” which literally means “excessive eating.”  They forage practically non-stop — up to 20 hours a day, building up fat reserves for hibernation, increasing their body weight up to 100% in some extreme cases.  Their daily food intake goes from 8,000 to 15-20,000 calories. Occasionally their eyes are bigger than their stomachs, and all that they’ve eaten comes back up.  Pictured is the aftermath of a Black Bear’s orgy in a cornfield.

If you  share a bear’s territory, be forewarned that they have excellent memories, especially for food sources.  Be sure not to leave food scraps or pet food outside and either delay feeding birds until bears are hibernating (late December would be safe most years) or take your feeders in at night.

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