At this time of year, a black bear could eat 10,000 to 20,000 calories per day as it bulks up in preparation for its winter hibernation (during which time it won’t eat, drink, urinate, or defecate). The typical person eats about 2,000 calories per day. So, if you were to eat as much as a bear, you would need to eat breakfast, lunch, and dinner five to 10 times, each. Every day.


Black oak acorns. (Photo by Steve Ryan)

What kind of tree can feed a bear this much?

The black oak. And, at this time of year, it provides most calories bears in Yosemite are getting.  A bear eating only acorns would have to eat over 1,600 acorns every day!

Aside from feeding bears, black oaks also feed deer, acorn woodpeckers, squirrels, jays, and probably some others I’m forgetting. Before 1851, acorns were the staple of the diet of the people living in Yosemite Valley (and, I imagine, throughout much of California).

Why do people, bears, deer, birds, and squirrels rely so much on acorns? They are incredibly nutritious, being rich in fat, protein, and carbohydrates, and containing a wide variety of vitamins and minerals.

So, aside from entertaining us with its yellow leaves in fall and sheltering us with its shade in the summer, the black oak truly is the tree of life.