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A C O R N S

Acorns

Up to 50 species of wildlife depend on acorns for a substantial part of their diet. Acorn woodpeckers, deer and the western gray squirrel are near the top of that list.In some years, acorns are not even available. So these species need to be somewhat elastic in their diet.

For humans you would just get a stomach ache if you ate straight acorns without leaching them. For several Native American tribes, acorns provided up to 50 percent of their diet. The Native Americans put acorns in a basket and put the basket in a running stream for a week or so to leach the tannins. One contemporary solution is putting acorn meal into a cloth bag and hanging the bag in a toilet tank to produce the same effect without wasting water.

The protein content is only 7.5 percent, while the fat content is 24.4 percent. It would almost be like eating butter. Acorns are also high in carbohydrates. For deer it's a tremendous energy source. In a good acorn year, deer will grow very fat and more twin fawns will be born the next spring. Given a choice, deer will eat about 90 percent acorns, if they're readily available. And they'll put on tremendous amounts of fat.

Oak trees in a good year are highly productive. Oak trees can produce up to 3,000 pounds of acorns per acre of canopy. By contrast typical annual grassland in California produces about 2,000 pounds per acre. But the acorn crops from blue oaks and valley oaks seem to be strongly correlated with temperatures in the spring, when they're flowering. And in fact, when it's drier, they tend to do better. Some oak trees take one year to produce their acorns; others take two. The lack of a consistent "masting" or seed-producing cycle in oaks may be a way that oak trees have developed to trick the animals that eat the seeds, keeping them from becoming so dependent on the crop that they are primed to eat it all. The trees produce so many acorns some years that the animals that feed on them can't possibly eat them all. To get past that gauntlet of predators and make it to grow up to be a big oak tree is very difficult, especially for valley oaks and blue oaks.

Some acorn woodpeckers will actually hatch a second nest of eggs in years when the crop is sufficient. Scrub jays eat acorns, and also "plant" them by stashing the nuts in places they hope to find again. Some of the hidden acorns end up in places where they can grow. Acorns for jays are just junk food. They store them up and use them as fast food.

Deamer 11/20/96