<P> The bright - blue breeding plumage of the male, easily observed on a wire or open perch, makes this species a favorite of birders . The male's call includes sometimes soft warbles of' jeew' or' chir - wi' or the melodious song' chiti WEEW wewidoo' . </P> <P> About two - thirds of the diet of an adult consists of insects and other invertebrates . The remainder of the bird's diet is made up of wild fruits or berries . Favored insect foods include grasshoppers, crickets, katydids, and beetles . Other food items include earthworms, spiders, millipedes, centipedes, sow bugs, and snails . </P> <P> Fruits are especially important when insects are scarce in the winter . Some preferred winter food sources include dogwood, hawthorn, wild grape, and sumac, and hackberry seeds . Supplemental fruits eaten include black raspberries, bayberries, fruit of honeysuckle, Virginia creeper, eastern juniper, and pokeberries . Bluebirds feed by perching on a high point, such as a branch or fence post, and swooping down to catch insects on or near the ground . The availability of a winter food source will often determine whether or not a bird will migrate . If bluebirds do remain in a region for the winter, they group and seek cover in heavy thickets, orchards, or other areas in which adequate food and cover resources are available . </P> <P> Eastern bluebirds are very social birds . At times, they gather in flocks of a hundred or more . However, they are territorial during the breeding season and may continue to defend a feeding area throughout the winter . Mating occurs in the spring and summer . A mature female typically raises two broods each season . Nests are constructed in trees within abandoned woodpecker holes or other cavities that provide adequate protection (usually several feet above ground). Construction of the nest is done primarily by the female and takes around 10 days to complete . These nests are small, cup - like structures lined with grass, feathers, stems, and hairs . Each female lays three to seven light - blue or, rarely, white eggs . The female incubates the eggs, which hatch after 13 to 16 days . The young cannot care for themselves upon hatching . The female broods the chicks for up to seven days after hatching . Fledglings then leave the nest 15 to 20 days after hatching . </P>

Where do eastern bluebirds go in the winter
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