The Ferruginous Pygmy-Owl is one of the most widespread birds of the lowlands of the Neotropics; the distribution of the species extends from the southern United States south to central Argentina. This species occurs in a wide variety of habitats. It does not occur in closed-canopy forest, although it is found at forest edge, but otherwise is found in almost any wooded habitat including arid scrub, dry forest, evergreen forests, coffee plantations, and towns. Most Ferruginous Pygmy-Owls are generally rufous ("ferruginous") in color, especially east of the Andes, but the plumage also may be a duller brown or gray-brown. This species shares the common pygmy-owl plumage pattern, with two large black marks ("false eyes") on the back of the neck, and white underparts with coarse streaks. It can be difficult to distinguish from other species of Glaucidium strictly by sight; the adult of the Ferruginous has short white streaks on the crown, however, but most of other species have spotted crowns. The song, a long series of short whistles, is a familiar sound; pygmy-owls often respond aggressively to imitations of this song, approaching the source in a rapid, direct flight. Ferruginous Pygmy-Owls sometimes are active by day, although they primarily are crepuscular. They prey on large insects and small vertebrates, including small birds that may be almost as large as the owl.