A Bunch of Acorns
Acorns are one of the most important foods for many species of squirrels, including the eastern gray squirrel. They gather and hide acorns in a behavior known as scatter hoarding. The squirrels are able to remember the locations of a remarkable number of acorns, and also use their keen sense of smell to locate the nuts. When a squirrel finds an acorn, she will always put it in her mouth to get some of her saliva on it. This makes it easier for her to locate it by its smell. It is said that a squirrel can locate an acorn that is buried through its sense of smell, even under a thick layer of snow. Squirrels also use their sense of smell to detect which acorns have been infested with insects.
Other animals also eat acorns, including birds such as blue jays, woodpeckers, pigeons and some ducks; deer, bears, pigs; and other rodents such as mice.
Some human societies, including some Native Americans and Koreans, have a tradition of using acorns in food. However, this is not particularly widespread, as many species of acorns contain highly acidic tannins which make them bitter and unpalatable. The tannins can be removed with processing, but can still make the acorn a lot of trouble for use as a food source. Animals such as squirrels that eat acorns have evolved the ability to metabolize tannins better than humans.