White-winged Crossbill
Loxia leucoptera

Migratory Status: Short-distance migrant

PIF Population Estimate: 20 000 000

Percent of western hemisphere population breeding in boreal forest: 85%

BAM Effective Detection Radius (m) : 85.3

PIF Maximum Detection Distance (m) : 125

Canadian BBS Population trend: -0.5 n.s. (-7.7 to 6.6)

Life History

The White-winged Crossbill is a true boreal species, with most of the North American population concentrated in the northern forests of Canada and Alaska. It typically occurs in large nomadic flocks, wandering the forests in search of heavy cone crops. The White-winged Crossbill is a medium-sized finch with distinctively crossed mandibles. Males and females are similarly patterned, having dark wings with two conspicuous white wing-bars. Males are pink to red overall, while females are brownish to yellow-olive. Immature birds have noticeably streaked underparts.

The White-winged Crossbill is generally restricted to conifer forests. They feed on seeds of spruce (Picea spp.) and tamarack (Larix larcina). White-winged Crossbills require large quantities of seeds; some individuals may consume up to 3000 per day. They are adept at choosing highly productive seed-bearing trees, while tending to avoid trees of poorer cone quality. Feeding is accomplished by holding a cone with their foot, then spreading apart the cone scales with their specialized crossed beaks to access the seeds. They will feed on cones attached to branches, or those that have fallen to the forest floor. When cone crops are poor, White-winged Crossbills will visit backyard feeding stations. However, their specialized bills are not very efficient in extracting non-conifer seeds.

Males are territorial and defend an area around the female and nest tree at the time of egg-laying. Defence rarely includes physical contact; rather the male flies toward intruders and escorts them away for 10 to 15 m before returning to its mate. Feed trees are not defended, as cone seeds are usually abundant when the birds are nesting. However, when flock sizes are large or cone crops poor, frequent scuffles occur.

Both sexes sing, but only the male does so regularly. A male White-winged Crossbill will sing while engaging in a slow-flapping, circular aerial display, or sing exuberantly from a tree top. The song is relatively long, consisting of trills, chirps and warbles, “trrr-tweet-tweet-tweet-trrr-tchet-tchet-tweet-tweet-tweet-trrrrr-tweet-tweet”. Males sing most often just before breeding. Calls are a series of dry rattling notes. When birds are actively feeding they call very little, but as they are about to leave a tree, the call intensity can build into a loud crescendo.

Reference(s)

Benkman, C. W. 1992. White-winged Crossbill (Loxia leucoptera), The Birds of North America Online, . A. Poole, Ed. Ithaca: Cornell Laboratory of Ornithology; Retrieved from The Birds of North America Online database: http://bna.birds.cornell.edu/bna/species/027