Description: A small owl lacking ear tufts. Male and female are similar in plumage. The eyebrows and lores are white and are bolder than the other white markings. Chest is white with rufous-brown streaks; iris of the eyes are lemon yellow; bill is yellow to greenish or grayish-yellow. The Ferruginous Pygmy-Owl is very similar to the Northern Pygmy-Owl with the distinctions of habitat, call, color, white crown streaking and usually tail band color. As the name implies (ferruginous is defined as reddish-brown or rust in color), a major distinctive field mark of this owl is the rufous or reddish-brown tail bars (the Northern Pygmy-Owl having white barring) and over all color (Note: there is a grayish phase in Mexico that is gray with white tail bars and a rarer red phase with no tail bars). The Ferruginous Pygmy also has white streaking on the forehead and head, where the Northern Pygmy's markings are more rounded spots. The backside of both Pygmy-Owls have similar white markings, but the over all color is more reddish-brown for the Ferrug (Texas birds are more gray-brown). The, so called, "false eyes" of the Pygmy-Owls are a distinctive pair of black patches bordered with white on the nape. The only actual overlap of range, between the two Pygmy-Owls, is in a very small area of Southern Arizona so the possibility of mistaking their identification is slight. In addition to this, the Ferrug is a lowland bird and the Northern Pygmy is a mountain bird (some overlap "might" occur only in winter when the Northern Pygmy may move down slope). The different calls of the Pygmy Owls may be the single best method of field separation. The male Ferruginous Pygmy's advertising call is described as a whistled "popping" sound and has a shorter interval between the notes than there is in the Northern Pygmy's. The female Ferrug, if present, may also respond to the male with a rapid "chitter".
Young: Although the white streaking on the forehead and head is not developed on the juvenile Ferruginous, the rust tail bars are, making identification possible. The young also have a high-pitched rattle begging call.