Amphispiza bilineata
black-throated sparrow

Amphispiza bilineata breeds in the southwest and central regions of North America, extending into the north-central mainland of Mexico. The summer range is much larger than the winter range in the United States. In the winters, it migrates to southern U.S. deserts (Clark,1999; Karl, 2000). (Clark, 1999; Karl, 2000)

The black-throated sparrow prefers a sparse, isolated desert environment. Hot, dry weather in the desert uplands, creosote bush and scrub environments are the most frequent habitats. These sparrows prefer terrain that is either steeply sloped or very flat. Besides desert uplands, they also favor alluvial fans and hill slopes, usually with much exposed rock and gravel pavement (INRIN; Karl, 2000).

Plants that are closely associated with this species include creosote bush and cholla cactus, catclaw, small mesquite, artemisia, rabbit-brush, purshia, dwarf juniper, yucca, agave, and sagebrush (Robbins, 1966).

Amphispiza bilineata have dark, conical bills and a black coat, throat and mask. A white supercilium and malar streak are also present. Their crown, back and wings are grey and their bellies are white. The round tail is long and black with a few white patches on outer feathers (INRIN).

Juvenile black-throated sparrows are much browner and have a faint adult face pattern. The young have facial stripes but are also finely streaked on throat, instead of a completely black throat (Robbins, 1966).

The black-throated sparrow breeds in most desert states of the United States and Mexico. In California, song and pair formation begin in February. Depending on the timing of the rains, nesting behavior begins in March and continues through mid-August. The nest is built from April to June and is normally well concealed in shrubs and bushes. In Idaho, all of the nests were within 25 cm of the ground. The nest is cup-shaped and loosely built of grasses and stems. It is lined with plant fibers, rabbit fur, cow hair, wool, and feathers. From April to August there are two broods, with usually 3 to 4 eggs laid in each. The eggs are either white or pale blue and average 17.3 to 13.8 mm in diameter. Incubation period and age when young fledge are unreported (DeLacy, 2001; INRIN; Kaufman, 1996).

Both parents play an active role in feeding the young. The male also protects the nest by using his song to warn off other conspecifics (Kaufman, 1996).

Black-throated sparrows are partly migratory. They are found in the southern portion of their breeding range throughout winter. These birds are oftentimes seen interspersed with white-crowned sparrows and Brewer's sparrows in the wintertime. During some seasons this species does not have access to a water source. It derives water from food it has eaten, ususally insects and seeds. This adaptation, along with its great tolerance for heat, makes it the best-suited sparrow for the desert climate. Except for the summer season when mate-pairing takes place, they are normally flocking birds.

Amphispiza bilineata builds cup-shaped nests in shrubs or cacti, usually close to the ground. In Idaho, all located nests have been 25 to 45 cm above ground in big sagebrush plants (Clark, 1999; DeLacy, 2001; INRIN; Karl, 2000).

Black-throated sparrows are omnivorous, eating seeds during winter months and insects during breeding season. They eat many flying insects, but also consume grasses and herbs. Gravel is sometimes ingested to aid in digestion. This bird can usually be observed running around on the ground in search of insects. The diet of insects allows these birds to obtain moisture from their food and not rely on free water throughout breeding season. If spring water is present they will take advantage of it. The young are fed insects, particularly grasshopper abdomens (Karl,1999; Clark, 2000; DeLacy, 2001).

Common foods eaten include: angiosperms (flowering plants), Poaceae (grasses), seeds from deciduous shrubs, arthropods, grasshoppers and crickets, and cockroaches. (Clark, 1999; DeLacy, 2001; Karl, 2000)

An anti-predation adaption the black-throated sparrow has developed is to "freeze" when a predator is near their nest. This most likely occurs because predators are more likely to search an area from where a bird has just been flushed (DeLacy, 2001; INRIN).

In Arizona and Texas, there have been reports of A. bilineata serving as a host to cowbirds (Terres, 1980).

There is no documented economic importance these birds have for humans. They add to the biodiversity of the desert and bring a beautiful chorus to the world.

This sparrow is a non-game bird protected by the Migratory Bird Treaty Act. In desert areas where development is increasing, its populations have declined. Unlike some desert birds, the black-throated sparrow does not adapt well to life in the suburbs. In proper habitat, however, its population is steady (INRIN; Kaufman, 1996).

In Arizona and Texas, there have been reports of A. bilineata serving as a host to cowbirds (Terres, 1980).