Adult sparrows are preyed upon by house cats and small raptors, while young may be taken by a range of mammals and reptiles.

The American sparrows are seed-eating New World birds with conical bills, brown or gray plumage, and distinctive head patterns.

Birds in the genus Aimophila tend to be medium-sized at 5 to 8 inches (13 to 20 cm) in length, live in arid scrubland, have long bills and tails in proportion to their body size as well as short, rounded wings, and build cup-shaped nests.

[2] Both sexes are similar in appearance, but the juvenile rufous-crowned sparrow has a brown crown and numerous streaks on its breast and flanks during the spring and autumn.

[12] The song is a short, fast, bubbling series of chip notes that can accelerate near the end, and the calls include a nasal chur and a thin tsi.

[11] The rufous-crowned sparrow is a non-migratory species, though the mountain subspecies are known to descend to lower elevations during severe winters.

[11] This sparrow is found in open oak woodlands and dry uplands with grassy vegetation and bushes.

[5] The rufous-crowned sparrow will at times forage in pairs during the breeding season, and in family-sized flocks in late summer and early autumn.

[11] Predators of adult sparrows include house cats and small raptors like Cooper's and sharp-shinned hawks, American kestrels, and white-tailed kites.

The head, neck and tail are lowered, wings held out, and feathers fluffed as the bird runs rapidly and voices a continuous alarm call.

[17] The rufous-crowned sparrow forages slowly on or near the ground by walking or hopping under shrubs or dense grasses.

Males attract a mate by singing from regular positions at the edge of their territories throughout the breeding season.

[11] While it is not known when precisely the breeding season starts, the earliest that a sparrow has been observed carrying nesting material was on March 2 in southern California.

[11] The female bird builds a bulky, thick-walled open-cup nest typically on the ground, though occasionally in a low bush up to 18 in (46 cm) above it, from dried grasses and rootlets, sometimes with strips of bark, small twigs, and weed stems.

[5][11] Nests are well hidden, as they are built near bushes or tall grasses or overhanging rock with concealing vegetation.

When a young rufous-crowned sparrow leaves the nest after eight or nine days, it is still incapable of flight, though it can run through the underbrush; during this time it is still fed by the parents.

Juveniles tend to leave their parent's territory and move into adjacent habitat in autumn or early winter.

Reproductive success varies strongly with annual rainfall and is highest in wet El Niño years, since cool rainy weather reduces the activity of snakes, the main predator of the sparrow's nests.

[24] The rufous-crowned sparrow is treated as a species of least concern, or not threatened with extinction, by BirdLife International due to its large geographical range of about 463,323 sq mi (1,200,000 km2), estimated population of 2.4 million individuals, and lack of a 30% population decline over the last ten years.

[11] Populations of the species in southern California are also becoming more restricted in range because of urbanization and agricultural development in the region.