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White-crowned Sparrows feed mainly on seeds of "weeds" and grasses in winter. Other plants material (buds, flowers, etc.) may also be taken at various seasons and, in summer, many insects and spiders are consumed.
In the southernmost coastal populations, pairs may remain together all year on permanent territories. Elsewhere, males arrive on the breeding grounds before females and defend territories by singing. In the north, the nest site is usually on the ground at the base of a shrub or grass clump, often in a shallow depression. Along the west coast, the nest is often placed a meter or so above the ground in a shrub.. The nest (built by the female) is an open cup made of grass, twigs, weeds, rootlets, and strips of bark and lined with fine grass, feathers, and animal hair. Clutch size is typically 4 or 5 eggs (sometimes 3, rarely 2 or 6). The eggs are creamy white to pale greenish and are heavily spotted with reddish brown. Incubation, which is by the female only, is for 11 to 14 days (usually 12). Both parents feed the nestlings, although the female may do more at first. Young leave the nest around 7 to 12 days after hatching, with those in the far northern part of the range tending to leave the nest earlier. The male may care for the fledglings while the female begins a second nesting attempt. In the far north, there is just one brood per year, but farther to the south there may be two, three, or even four broods per year.
Although some populations on the Pacific coast are permanent residents, elsewhere these sparrows are highly migratory. Most migration occurs at night and, on average, females winter farther south than males.
The geographic song dialects of White-crowned Sparrows have been studied extensively.
(Kaufman 1996; AOU 1998; Dunn and Alderfer 2011)