Acorns are one of the most important wildlife foods in areas where
oaks occur.
Wildlife which eat acorns as an important part of their diets
include jays, pigeons, some ducks and several species of
woodpeckers. Small mammals that feed on acorns include mice,
squirrels and several other rodents. Larger mammals including pigs,
bears and deer, also consume large amounts of acorns. Acorns are
attractive to animals because they are large and thus efficiently
consumed or cached. Acorns are also rich in nutrients. Percentages
vary from species to species, but all acorns contain large amounts
of protein, carbohydrates and fats, as well as the minerals
calcium, phosphorus and potassium, and the vitamin niacin. Total
food energy in an acorn also varies by species, but all compare
well with other wild foods and with other nuts. Animals that cache
acorns, such as jays and squirrels, may wait to consume some of
these acorns until sufficient groundwater has percolated through
them to leach out the tannins. Other animals buffer their acorn
diet with other foods. Many insects, birds, and mammals metabolize
tannins with fewer ill effects than humans. Species of acorn that
contain large amounts of tannins are very bitter, astringent, and
potentially irritating if eaten raw. This is particularly true of
the acorns of red oaks. The acorns of white oaks, being much lower
in tannins, are nutty in flavor, which is enhanced if the acorns
are given a light roast before grinding. Acorns of the white oak
group typically start rooting as soon as they are in contact with
the soil (in the fall), then send up the leaf shoot in the
spring.