We think we know them simply because we see them and hear them every day. If you live in Chicago, that means sparrows, pigeons, robins, starlings, and doves, not to mention finches, cardinals, crows, grackles, red-winged blackbirds, swallows, swifts, geese, gulls, kestrels, peregrine falcons (if you’re lucky), and many others, and that’s not taking into account migrating birds.