| Common Crossbill | ||||||||||||||
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Male Common Crossbill | ||||||||||||||
| Scientific classification | ||||||||||||||
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| Binomial name | ||||||||||||||
| Loxia curvirostra |
The Common Crossbill, Loxia curvirostra , is a small passerine bird in the finch family Fringillidae.
This bird breeds in the pine, forests of North America, where it is known as Red Crossbill, Europe and Asia. It nests in conifers, laying 3-5 eggs.
This crossbill is mainly resident, but will regularly erupts south if its food source fails. This species will form flocks outside the breeding season, often mixed with other crossbills.
The crossbills are characterised by the mandibles crossing at their tips, which gives the group its English name. They are specialist feeders on conifer cones, and the unusual bill shape is an adaptation to assist the extraction of the seeds from the cone.
Adult males tend to be red or orange in colour, and females green or yellow, but there is much variation.
This species is difficult to separate from Parrot Crossbill and Scottish Crossbill, both of which breed within its Eurasian range. The identification problem is less severe in North America, where only Red Crossbill and White-winged Crossbill occur.
Plumage distinctions from Parrot and Scottish Crossbills are negligible. The head and bill are smaller than in either of the other species. Care is needed to identify this species. The glip call is probably the best indicator.
Work on vocalisation in North America suggest that, in that continent alone, there are eight or nine populations of Red Crossbill which do not interbreed, although few ornithologists seem inclined to give these forms species status. These forms also vary in terms of bill size and structure, tending to specialize on the seed cones of different species of conifer.