Black-chinned sparrow

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The black-chinned sparrow (Spizella atrogularis) is a small, slim gray bird in the sparrow family. It lives in the southwestern United States and much of Mexico north of the Isthmus of Tehuantepec. Most birds in the United States migrate south after breeding, while many in Mexico stay year-round.

Appearance
The bird is about 13–15 cm long and weighs 9–14 g. It has a gray head and body, a reddish-brown back with black streaks, brown wings and tail, a pink beak, and brownish legs. During the breeding season the male shows black on the chin and throat and the front of the face. Females, youngsters, and nonbreeding males have little or no black on these areas. The bird spends a lot of time foraging on the ground and often travels in small groups.

Habitat and range
It favors dry, brushy habitats like chaparral, sagebrush, and pine-juniper woodlands, usually in remote, rugged areas. It can be found from near sea level up to about 2,400 meters in the United States, and from 300 to 2,500 meters in Mexico. In migration, it may pass through montane forests but is not common in mixed pine-oak forests. Most northern birds move south for winter.

Diet and behavior
The sparrow is mainly a ground forager. In winter it eats seeds; in summer it eats more insects. It may also eat some seeds from bushes and catch insects in flight. It sings from visible perches to defend its territory, sometimes with nearby males.

Breeding
Nesting happens mainly from late April to June, sometimes into July. The female builds a shallow cup nest from grasses and plant fibers, usually within a dense shrub, a short distance from the ground. She lays 2–5 pale blue eggs, which she largely incubates for about 13 days. Both parents feed the young after they hatch, which fledge about 11–13 days later. Most pairs raise one brood per year, though a few may try a second in southern California. Nest predation is common, with garter snakes and other predators a threat.

Conservation and threats
The black-chinned sparrow is currently listed as Least Concern by the IUCN because it has a large range and a relatively large population. However, its numbers are believed to be decreasing, and estimates vary widely. Habitat loss, fragmentation, and climate change could negatively impact it. Climate warming may push its breeding range northward, while the winter range could remain more stable or even expand in some areas. The species is a useful indicator of environmental change because it is sensitive to habitat changes.