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The nutcrackers (''Nucifraga'') are a genus of three species of passerine bird, in the family Corvidae, related to the jays and crows. One, the spotted nutcracker (''Nucifraga caryocatactes''), occurs in Europe and Asia. The next, the large-spotted nutcracker (''Nucifraga multipunctata'') occurs in the Himalayas and is sometimes considered a subspecies of the spotted. The last, the Clark's nutcracker (''Nucifraga columbiana''), occurs in western North America. The most important food resources for both these species are the seeds (pine nuts) of various pines (''Pinus'' sp.), principally the cold-climate (far northern or high altitude) species of white pine (''Pinus'' subgenus ''Strobus'') with large seeds: ''P. albicaulis, P. armandii, P. cembra, P. flexilis, P. koraiensis, P. parviflora, P. peuce, P. pumila, P. sibirica'' and ''P. wallichiana'', and also the pinyon and lacebark pines in subgenus ''Ducampopinus''. In some regions, where none of these pines occur, the seeds of spruce (''Picea'' sp.) and hazelnuts (''Corylus'' sp.) form an important part of the diet too. The bills of these birds are specialized tools for extracting seeds from pine cones. Surplus seed is always stored for later use, and it is this genus that is responsible for the re-establishment of their favoured pines over large areas either burnt in forest fires or cleared by man. The nutcracker can store as many as 30,000 pine nuts in a single season, remembering the location of as many as 70% of their stash, even when buried in snow.〔http://www.bbc.co.uk/programmes/b00jmqk1〕 Various insects are also taken, including bee and wasp larvae, and also birds' eggs and nestlings, and carrion if it is found. Nesting is always early in this genus, so as to make the best use of pine nuts stored the previous autumn. The nest is usually built high in a conifer. There are normally 2–4 eggs laid and incubated for 18 days. Both sexes feed the young which are usually fledged by about 23 days and stay with their parents for many months, following them to learn food storage techniques. None of the species are migratory, but they will leave their usual ranges if a cone crop failure causes a food shortage. == References == 〔 * Lanner, R. M. (1996). ''Made for each other: a symbiosis of birds and pines''. OUP ISBN 0-19-508903-0 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「Nutcracker (bird)」の詳細全文を読む スポンサード リンク
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