The White Winged Crossbill of the Pacific Northwest
White winged crossbills occur irregularly throughout the northern boreal forests of North America. In a broad band that ranges across Canada from Newfoundland to British Columbia into Alaska and the Northern Territories of Canada.
Although its very rare to see them on the outer islands, sometimes they come in huge flocks to feed on Alder Seeds during the winter months.
White winged crossbills breed in forests of black and white spruce, feeding on the seeds. Within their normal range, large movements of white winged crossbill populations occur when local seeds become scarce.
Members of a flock can tell when other crossbills are successfully feeding and they will join them. The number of seeds per cone varies from tree to tree, and those trees with high seed counts are favored. When the feed is abundant, the flock is usually quiet. Calling seems to indicate poor foraging, and the level of calling increases just before a flock takes flight to find another tree. Crossbills feed acrobatically, even upside down, on cones whose scales are open without detaching the cone.
When cones are closed, crossbills bite them off and hold the cone with a foot while they open the cone with their bills. White winged crossbills are superbly adapted to feeding on the seeds of conifers. They use their crossed mandibles to open the scales of cones so that their tongue can lift out the seed hidden between the scales. A crossbill can consume up to 3000 seeds in one day.
Although the white winged crossbill has three breeding periods coinciding with the cyclical abundance of favorite food sources. In early July, January and March. Their nests are usually bulky and hidden in thick spruce boughs.
White winged crossbills, like red crossbills, have thick conical blackish bills with distinctive crossed mandibles. The black tail is forked in both sexes, the wings are black with two broad, white wing bars and white tips on the feathers. The wing bars are visible at all times and can be used to tell them apart from red crossbills.
The body color of the adult female is a finely dark streaked olive, variably tinged with green or yellow. She has dusky eye stripes. The back is heavily mottled. The lower belly, thighs, and under tail coverts are pale buff to pale green.