Sparrow, gregarious, seed-eating bird of the subfamily Passerinae of the weaver-bird family. There are 8 genera: 5 confined to Africa, the other 3—the true sparrows, rock sparrows, and snow finches—are also found in the Palearctic. Of the true sparrows, one species, the house sparrow (Passer domesticus), has been successfully introduced to the Americas. Closely associated with human habitation, it is the only bird not known to occur in a “natural” habitat but always with human beings. In the United states some small finches are called sparrows (song sparrow, tree sparrow, field sparrow, etc.).