Early explorers in America told of huge flocks of passenger pigeons that stripped oak trees of nuts in a matter of minutes. By the end of the 1800s the cutting of forests to make way for farmers had so reduced the mast supply that turkey and pigeon populations plummeted. Market hunting decimated the flocks of birds even more. By 1912 the passenger pigeon was extinct and turkeys were nearly so. Bread served at the first Thanksgiving was likely made from acorn flour.
Acorns are of value beyond being food sources.
An insect called the Acorn Weevil lays eggs inside ripe acorns where the wormy offspring consume their nutty meals in safety. Uneaten worms eventually exit as beetles from a hollow acorn. When the young beetles exit, the empty acorn shell is a waiting apartment for spiders, millipedes, or the eggs of the Acorn Moth. Eventually the acorn is decomposed by fungi and reverts to soil. The bark fissures of a mature oak tree often hide tiny insects, spiders, insect larvae, and the stored seed-meals of nuthatches and woodpeckers.