Passerella iliaca
fox sparrow

Fox sparrows, Passerella iliaca, are found in much of northern and western North America. In the summer during their breeding season, they are found across northern Canada and Alaska, and also south through parts of western North America. During the winter they migrate towards the Pacific coast, from southern British Columbia and south to northern Baja California. They also extend across the southern area of the United States, from northern Mexico to Illinois and Connecticut. (Byers, Curson, and Olsson, 1995)

Fox sparrows commonly breed in coniferous or mixed forests, which have dense undergrowth and shrub. They also breed in woodland thickets, scrub, chaparral, and riparian woodland. During the winter months, fox sparrows are commonly found in forests, forest edges, woodlots, and other woodland habitats that have dense undergrowth. (Alsop III et al., 2001; Byers, Curson, and Olsson, 1995)

Fox sparrows are one of the largest of sparrows, measuring from 15 to 19 cm in length, and weighing from 26.9 to 49.0 grams. Their wingspan is typically from 26.67 to 29.85 cm and their basal metabolic rate is 66.9 cm^ oxygen per hour, on average. Fox sparrows are divided into 18 different races, all of which are large, but each looks slightly different. All fox sparrows also have a long tail and a bi-colored dark and pale yellow bill. They also have dark brown streaks on their breasts that meet at one common point. The 18 races are divided into three larger groups, including the northern and eastern birds, the southern Rocky Mountain and Sierra birds, and the northern Pacific coast birds. The eastern and northern races have a grayish head that is streaked with rust, and a red or rust rump and tail. They also have a blotchy white breast. The southern Rocky Mountain and Sierra group has a solid gray head, and also has a rust colored rump and tail. Finally, the northern Pacific coast group is very uniform and dark brown in color. Within each of the races, the individuals show no significant differences in coloration between males and females. The males are slightly larger than the females. Juvenile fox sparrows are very similar to the adults in appearance, however the upper-parts are slightly duller and the streaks on the breast are smaller and narrower. (Byers, Curson, and Olsson, 1995; Canterbury, 2002; Trerres, 1980)

The oldest fox sparrow recovered at the Patuxent Wildlife Research Center was in 9 years and 8 months old. (USGS Patuxent Wildlife Research Center, 2003)

Fox sparrows tend to be solitary or in pairs during breeding season, and they travel in small flocks during migration. The male is a very active singer during the breeding season. They are diurnal. During the migration period, they generally migrate at night and sing during the day. During the breeding season, males are very territorial and actively defend their territories. One way they defend it is by darting at the invader, forcing them to leave. They are strong and direct fliers. They alternate short flights of rapidly beating their wings, with brief periods with their wings pulled to their sides. (Alsop III et al., 2001; Bent, 1968; Rising, 1996; Stanford Alumni, 1999)

Home Range

We do not have information on home range for this species at this time. (Baicich and Harrison, 1997)

Fox sparrows have a voice that is thought to be one of the finest among sparrows. The song is generally presented while the sparrow sits on the top of a bush or on a low branch in a tree. The male usually sings in a concealed area in the territory around its nest. Fox sparrows sing very often during breeding season, but keep themselves hidden at the same time. A distinctive song is one that is used when the bird is alarmed. It is commonly heard when fox sparrows are in some way disturbed near their nest. Singing is occasional, but not common, in the winter. (Alsop III et al., 2001; Bent, 1968; Byers, Curson, and Olsson, 1995; Trerres, 1980)

Fox sparrows are omnivorous. They forage on the ground by double scratching and quickly kicking backwards with both feet simultaneously. They dig holes in the leaf litter and ground, which allows them to reach buried seeds or insects. They look for weed seeds, blueberries, other wild fruit and especially Polygonum (knotweed). They also look for spiders (Araneae), insects, millipedes (Diplopoda), and small snails (class Gastropoda). Nestlings are fed primarily insects. (Alsop III et al., 2001; Byers, Curson, and Olsson, 1995; Trerres, 1980)

Because their nests are placed on the ground, fox sparrows face predation by hawks (family Accipitridae), mammalian carnivores (order Carnivora), and possibly snakes (suborder Serpentes). In order to protect their young when there is a predator, adults give a broken wing display. During the display the adult limps around with one wing up, acting as if it was broken, and calls sharply. Once the predator is distracted, the adult flies back to the nest and young. (Bent, 1968; Trerres, 1980)

Fox sparrows act as predators of insects, spiders, millipedes and small snails and are important prey for their predators. It is also interesting to note that fox sparrows are occasionally parasitized by brown-headed cowbirds (Molothrus ater). (Alsop III et al., 2001; Trerres, 1980)

There are no known adverse affects of Paserella iliaca on humans.

While fox sparrows do not play a large economically important role, they are important in the bird watching community. (Bent, 1968)

Fox sparrows are protected under the US Migratory Bird Treaty Act. They are particularly vulnerable to habitat destruction as a result of logging operations. (Alsop III et al., 2001; U.S. Fish and Wildlife Service, Date Unknown)

Fox sparrows are also referred to as ferruginous finches, foxy finches, fox-colored sparrows, and fox tails. They get their common name from the red or rusty color of their feathers. (Trerres, 1980)