Sunday, December 11, 2011


Male White-winged Crossbill in ornamental Douglas Fir -- © Dave Spier

Crossbills -- © Dave Spier

           White-winged Crossbills, an irruptive species in winter, are frequently reported on NNY Birds.  Their traditional diet of Canadian spruce seeds sometimes runs low and once exhausted, the birds head south in higher numbers.  The birds' small, thin bills, which are crossed at the tips, allow them to specialize on the small, soft cones of Spruces (White, Black, and Red), larch, Eastern Hemlock, Northern White Cedar and Red Cedar.  The White Pine, unlike other eastern pines, has soft cones that can be utilized by crossbills.  They also use Douglas Fir and Blue Spruce, introduced species in the east.

          White-winged Crossbills (Loxia leucoptera) are medium-sized finches with a year-round range from Alaska eastward through the boreal forest zone to the Canadian Maritimes.  There’s a fair number of breeding reports from around the Adirondacks with a concentration of confirmed sightings in northern Herkimer County and adjacent Hamilton County.

           In the winter, they migrate erratically into the northern states with sporadic reports from the central states.  Adult males are dull red with black wings and two prominent white wingbars.  Females are yellowish gray with similar wings.  Juveniles are heavily streaked and somewhat resemble Pine Siskins, another winter visitor.   In Europe the white-winged is called the Two-barred Crossbill.

            Another species, the Red Crossbill (Loxia curvirostra) is similar, but has a heavier bill and lacks the white wing bars.  [In rare cases, a variant of the first-year male can display weak wingbars.]  There are nine recognized "types" (similar to subspecies) of Red Crossbills and some of these may be evolving into separate species.  The specially adapted beaks are pointed and crossed at the tips, but the size and exact structure varies among the different types depending on the species of cone they are best adapted to.  The heavier bill allows Red Crossbills to pry out seeds from heavy pine cones in addition to spruce and fir.  An individual crossbill can extract and eat 3000 conifer seeds in one day, which probably explains why they keep moving in search of new food sources.

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