Common Crossbill - Loxia curvirostra

Common Crossbill

Loxia curvirostra

Order : Passeriformes

Family : Fringillidae ;

Biometrics :

Size : 17 cm
Wingspan : 27 à 29 cm
Weight : 40 g

Longevity : 4 years

IUCN conservation status :

Extinct

Threatened

Least
concern

Extinc
in the Wild

Near
threatened

Not
evaluated

EX EW CR EN VU NT LC NE

Geographic range :

Synonyms : Klyost-yelovik (ru), Mindre korsnäbb (sv), Piquituerto común (es), Crociere (it), Fichtenkreuzschnabel (al), Kruisbek (nl), Common Crossbill (en)

Physical description :
Red Crossbill is a large, plump finch, with very distinctive bill.
Red Crossbill adult male has brick-red plumage. Wings are dark greyish brown. Cleft tail is blackish-brown. There is individual variation; some males appear yellowish or orange-red. Others may be mottled greenish-yellow and red. Mantle and back may show some darker feathers. Rump is often brighter in colour.
Head is dull red, with brighter colours on forehead and crown. Large bill has crossed mandible tips. It is thick and curved. Eyes are dark brown. Legs and feet are black.
Adult female is dull greenish-yellow, with yellowier rump. Upperparts are slightly streaked. Some females are duller with greyish colours.
Juvenile is greyish-brown, heavily streaked with dark overall. Streaked underparts are whitish. It has thin buffy wing bars, formed by pale fringes on fresh feathers.
Immature resembles adult female, but some young males may show reddish or mixed red and yellow plumage.

There are four other species. These birds are the only birds having crossed bills in the world.
The Red Crossbill, Loxia curvirostra, from Eurasia, including Great Britain, feeds mainly in Spruces. Eleven subspecies are recorded in the Old World. They differ by size and colours, with different sizes of bills, according to the kind of conifers in their range.
The Scottish Crossbill, Loxia scotica, from Scottish, has larger bill, in order to feed on pine cones of exotic plantations in the north of their habitat. Now considered as distinct species, it is endemic of Great Britain. Variation in size and bill-shape are recorded in 8 subspecies of the New World.
The Parrot Crossbill, Loxia pytyopsittacus, from northern Europe and western Russia, and small population in Scotland. It feeds on cones of Scot pines (pinus sylvestris).
Two-barred Crossbill, Loxia leucoptera, breeds in coniferous forests in Alaska, Canada, and northern United States and across Asia to northeast Europe. It has white wing bars, which give it the other name White-winged Crossbill. It feeds on Larch seeds.

Voice :
Sound from CD 'Tous les Oiseaux d'Europe' by Jean C. Roché by courtesy of Sittelle and CEBA. Red Crossbill utters a loud, persistent and explosive 'chip-chip' call. We can hear several other calls, a harsh 'chewk' when alarmed or excited, and a ringing flight call 'jip-jip-jip'. Song is a trill followed by Greenfinch like calls, but more varied.

Habitat : Red Crossbill lives in coniferous forests, spruces or pines.
GEOGRAPHIC RANGE: Red Crossbill is found in North America, southern Alaska to Newfoundland, and southwards to northern United States, North Carolina and Central America. Also across Northern Eurasia, northern Africa, south-eastern Asia and Philippines.
Resident in its breeding range, it may move southwards according to food resources.

Behaviour : Red Crossbill feeds mainly on conifer seeds. It extracts the seeds with its crossed bill. It has strong asymmetrical jaw muscles, assisting the twisting movement necessary to extract the seed. Cone is broken from the tree with considerable effort. Then, the bird carries it on convenient branch, holding it firmly by the feet in order to extract each seed in repeated movements. They start at the bottom of a cone, and spiral upwards, prying open each scale and getting the seed with the tongue.
Increasing of conifer plantations makes these birds widespread in their habitat. They are detected by extracted seeds lying on the forest floor. They often feed in flocks.
Red Crossbills perform movements according to food resources, and they may irrupt out of their range is food is scarce. For the same reason, they may breed in areas far south of their normal range. They breed when food is abundant, at any month of the year, and several broods are produced if an abundant food source is found.
Birds in juvenile plumage may be seen all the year, except January and February, and family groups travel with juveniles still fed by parents.
Red Crossbills have different flight calls, and each type of sound is uttered by birds with different bill shape. They also prefer to feed on seeds of different conifers with different size cones. Flocks maintain contact with distinctive flight call. These calls allow the isolation of each group.
Red Crossbill pairs are monogamous, and form within flocks.

Flight : Red Crossbill performs a swift bounding flight with rapid wing beats. Flocks move through the tree tops.

Reproduction-nesting : Red Crossbill's nest is located high in conifers, on a horizontal branch, among a cluster of twigs and overhanging vegetation, in order to hide and protect it. Female builds the nest. It is a bulky cup of loose twigs, made with grass and bark strips. It is lined with finer material, grass, lichen, feathers and hair. Winter nests are more compact than summer nests. Materials and constructions are different, according to the weather of the season.
Female lays 3 to 4 pale blue-green eggs, spotted with brown and lavender. Incubation lasts about 12 to 16 days, by female. She is fed by the male by regurgitation. Altricial chicks are fed by the male during five days, and then, both parents bring food to the young. They leave the nest at about 18 to 22 days after hatching. They are still fed by parents for a month more.
Their bills are not crossed at hatching, but cross as they grow. They need 45 days to have their bills crossed enough to extract seeds themselves.
This species produces one or two broods per season, but it depends of its range.

Food habits : Red Crossbill feeds mainly on seeds of conifers, but they also consume buds of trees, weed seeds, berries and insects (aphids).

Protection / threats : At this time, Red Crossbills are common and widespread in their ranges, but they depend of mature forests for food. Populations seem to be stable in most areas, but some declines are observed where deforestation is too rapid.

Other links :
Iucn
Birdlife

Specification sheet created by Nicole Bouglouan

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