A finch with a uniquely crossed bill — the upper and lower mandibles overlap like a pair of scissors, allowing it to prise open pine and spruce cones and extract the seeds inside with precision; crossbills can breed in the depths of winter when cones are ripe, sometimes nesting in snow.
The crossed bill
The crossbill’s most distinctive feature is its bill, in which the upper and lower mandibles cross over each other — the direction of crossing varies between individuals. This is not a deformity but a precision tool: the bird inserts its bill under a cone scale, then as it closes and twists its bill, the crossed tips lever the scale apart, exposing the seed. The tongue then flicks the seed into the mouth. Crossbills can open dozens of cones per hour.
Cone nomads
Crossbills are entirely dependent on the crops of conifer cones — spruce, pine, larch, and fir. Cone crops vary dramatically between years and regions, so crossbills are nomadic, moving across vast distances to track cone availability. In irruption years, when northern cone crops fail, thousands pour into Britain and Western Europe, sometimes settling to breed in areas where they are normally absent.
Winter breeding
Crossbills are among very few birds that breed in mid-winter — sometimes as early as January and February in Britain. They time their breeding to coincide with peak cone availability rather than temperature or day length. A nest can be built on a snow-covered conifer branch, with the incubating female insulated by her thick plumage.
Colour dimorphism
Adult males are brick-red to orange-red; females and immatures are greenish-grey. Young males pass through orange intermediate plumages before acquiring full adult colour. The red pigment is derived from carotenoids in the seeds they eat.
Find more birds by letter
Crossbill starts with C and ends with L. Browse other birds along the same letter.
Birds that contain a letter from "Crossbill":