Introduction

Editor's Note 01/06: On the basis of vocal and morphological differences, the Hispaniolan Crossbill (Loxia megaplaga) is now considered a separate species from the White-winged (L. leucoptera). Future revisions of this account will reflect this change.

In North America, White-winged Crossbills (L. l. leucoptera) occupy boreal coniferous forests from Alaska to Newfoundland and south into the Washington Cascades, the central Rocky Mountains, and the northeastern states. Other races of this species breed in the Palearctic from northern Scandinavia to Siberia (L. l. bifasciata), and in the mountains of Hispaniola (L. l. megaplaga). Like other crossbills, this species is specialized for foraging on seeds in conifer cones, and much of its behavior and ecology can be understood in terms of tracking this highly variable food resource. Often traveling in large flocks, these birds are highly efficient at finding and extracting conifer seeds, using their crossed bills to wedge open cone scales and then lifting seeds free with their tongues. Individuals can eat up to 3,000 conifer seeds per day, although their specialized bill makes them much less efficient than other finches at exploiting non-conifer seeds.

Shifts in the diet of this species reflect changes in the rates at which seed from different conifers can be consumed, and crossbill movements between areas are often timed to exploit developing cone crops. Breeding is opportunistic and can occur throughout the year, whenever food intake is sufficient for the female to form eggs and raise young. Although they can be locally abundant, nomadism has limited field studies of this and other crossbills.