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The eastern bluebird (''Sialia sialis'') is a small bird found in open woodlands, farmlands, and orchards. It is the state bird of Missouri〔 and New York. This species measures long, spans across the wings, and weighs .〔〔 Eastern bluebirds are found east of the Rockies, southern Canada to the Gulf states, and southeastern Arizona to Nicaragua. The increase in trees throughout the Great Plains during the past century due to fire suppression and tree planting facilitated the western range expansion of the eastern bluebird〔Gowaty PA, Plissner GH. 1998. Eastern Bluebird (''Sialia sialis''), no. 381. In: A. Poole (ed.). The Birds of North America Online. Cornell Lab of Ornithology, Ithaca, New York.〕 as well as range expansions of many other species of birds.〔Livezey KB. 2009a. Range expansion of Barred Owls, part I: chronology and distribution. American Midland Naturalist 161:49–56.〕〔Livezey KB. 2009b. Range expansion of Barred Owls, part 2: facilitating ecological changes. American Midland Naturalist 161:323–349.〕〔Livezey KB. 2010. Killing barred owls to help spotted owls II: implications for many other range-expanding species. Northwestern Naturalist 91:251–270.〕 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'.〔 ==Food== 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. 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Eastern bluebird」の詳細全文を読む スポンサード リンク
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