White-winged Crossbill (Loxia leucoptera)

[order] PASSERIFORMES | [family] Fringillidae | [latin] Loxia leucoptera | [UK] White-winged Crossbill | [FR] Bec-croise bifascie | [DE] Binden-Kreuzschnabel | [ES] Piquituerto Franjeado | [NL] Witbandkruisbek

Subspecies

Physical charateristics

White-winged Crossbills are finches with highly specialized, crossed bills and long, pointed wings. Male White-winged Crossbills are rosy-red with black wings and two white wing-bars. Females are dark greenish-yellow with black wings and white wing-bars. Juveniles are streaked brown, also with wing-bars.
White-winged Crossbills can be found in large flocks year round and call when they are foraging in an unproductive area. When many seeds are available they remain quiet. If only a few birds call, the flock continues to forage, but if a number of birds call, the flock will move on to find a more productive spot. Their bills are adapted for removing seeds from cones, and they start at the bottom of a cone and spiral upward, prying open each scale and removing the seeds with their tongues. The bills can cross in either direction, and the direction of the cross dictates the direction that the bird spirals up the cone. They can eat up to 3,000 seeds a day.

Listen to the sound of White-winged Crossbill

[audio:http://www.aviflevoland.nl/sounddb/W/White-winged Crossbill.mp3]

Copyright remark: Most sounds derived from xeno-canto

Range

Eurasia, North America : North

Habitat

White-winged Crossbills are a far northern species, typically found in boreal forests with mature Engleman spruce and larch. They may also use western and mountain hemlock

Reproduction

The breeding cycle of White-winged Crossbills is more closely tied to food availability than it is to season. They can breed at any time of year, often in mid-winter if there is an abundant source of seeds. They may be able to breed as young as five months old, and can have multiple clutches in a year. This results in a high reproductive potential. They are monogamous, and pairs form within flocks. The female builds the nest, which is typically on a horizontal branch high up in a spruce tree. The nest is an open cup of twigs, weeds, grass, and bark strips, lined with rootlets, lichen, moss, and hair. The female incubates 2 to 4 eggs for about 12 to 14 days. The male brings food to the incubating female and to the young for the first few days after they hatch. After about five days of continuous brooding, the female joins the male in bringing food to the young. The young leave the nest after about 18 to 22 days. Once the young fledge, the male may continue to care for them while the female begins a second clutch. The young birds’ mandibles begin to cross about two weeks after they fledge, and they learn to extract seeds soon after that.

Feeding habits

Primarily feeds on spruce seeds if they area available. They will also feed on seeds of other conifers, tree buds, berries, other seeds, and insects.

Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Migration

Resident and dispersive; also eruptive. In most years makes only limited movements in response to local food shortages. In occasional years, like Crossbill, makes eruptive movements, associated with shortage of preferred food (seed of larch Larix) and high population density. Birds move west or south-west, regularly reaching Finland and Sweden and occasionally various parts of eastern, central, and western Europe. In exceptional 1889 invasion, reported south to Switzerland, northern Italy, and Hungary, west to Britain and Netherlands. In more typical 1956 invasion, many observations in Finland, with small numbers continuing south-west to Sweden, Norway, Denmark, Germany, and Belgium. Invasions usually reach Scandinavia and Britain in July, continuing chiefly to September or October; recorded in central Europe later, mostly from September. Return movement February or March to early June. In Sweden, occurs every year in strongly varying numbers, and increasingly since 1976; recent major invasions (600-800 birds recorded) in 1979 and in 3 consecutive years (probably for first time since records began in 1786) 1985, 1986, and 1987; largest ever in 1990 (more than 2300 birds), but only c. 170 in 1991. Sometimes breeds in spring following invasion (e.g. 1957, 1987), as also in other countries.

Distribution map