Crossbills
| Crossbills | ||||||||||||
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Crossbill ♂♂ ( Loxia curvirostra ) |
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Loxia | ||||||||||||
| Linnaeus , 1758 |
The cross-bills ( Loxia ) constitute a genus within the family of finches represents (Fringillidae) which holarctic is widespread. Characteristic and eponymous for this genus are the laterally shifted, crossing tips of the upper and lower beak. The habitat of crossbills are coniferous forests.
features
The males of the crossbills have a red-orange or orange-gray plumage. The females, on the other hand, have plumage that is olive gray or gray.
The special beak shape of these birds led to their naming: the upper and lower bills cross sideways in their front area. This enables the crossbills to get to the seeds in the cones of conifers , which are their main food.
Distribution area
Of the five species, one is found in Northern Europe, one in Scotland, two in the Holarctic and one on the island of Hispaniola in the Caribbean. The crossbill is the most widespread species. It also breeds in North Africa, including in the mountains of Morocco and Algeria.
In particular, the two Holarctic species, namely the crossbill and the two-barred crossbill , occasionally show invasive behavior. Because both species relocate some of their breeding sites and residence areas in order to take advantage of a particularly rich supply of spruce seeds. For this reason, invasions can sometimes also be observed over large areas, during which crossbills are in regions where they do not otherwise appear regularly or only at greater intervals. In such invasions, birds from northern Russia or Scandinavia sometimes reach southern central Europe or even the Mediterranean coast. Such inflows, observed for example in 1909, 1930 and 1935, coincided with a large-scale fall of spruce seeds in Fennoscandinavia and northern Russia. Between 500,000 and 5,000,000 crossbills were found in Scotland during the 1990 invasion.
food
The diet consists mainly of spruce seeds. Conifer seeds are extracted from the large crossbills by wedge-like insertion of the laterally compressed bill between the cone scales, airing the cover scales by vigorously shifting the lower jaw to the side and picking out the seeds clamped underneath with the tongue. The crossed beak tips do not develop young birds until several weeks after they hatch. Even after they have left the family, the parent birds provide them with food for a few weeks. In the case of the Scottish crossbill, it is even considered possible that this period extends over eight weeks.
Reproduction
Crossbills are nomads who, regardless of the season and weather, breed wherever there is an abundance of cones in the tree tops. They build their nests high in spruce trees. The clutches usually consist of 3–4 eggs, which are incubated for 13–16 days. The nestling period is 14-25 days. Usually there are two broods a year.
species
- Crossbills ( Loxia )
- Pine crossbill ( L. pytyopsittacus )
- Scottish Crossbill or Scottish Crossbill ( L. scotica )
- Crossbill ( L. curvirostra ), the subspecies L. c. sinesciuris will u. a. from the AOU as a separate species L. sinesciuris out
- Crossbill ( L. leucoptera )
- Hispaniola crossbill or Haiti crossbill ( L. megaplaga ) (originally considered a subspecies of the crossbill)
literature
- Einhard Bezzel: birds. BLV Verlagsgesellschaft, Munich 1996, ISBN 3-405-14736-0 .
- C. Hilary Fry and Stuart Keith (Eds.): The Birds of Africa - Volume VII. Christopher Helm, London 2004, ISBN 0-7136-6531-9 .
- Collin Harrison, Peter Castell: Fledglings, Eggs and Nests of Birds in Europe, North Africa and the Middle East. 2nd, revised edition, German licensed edition. Aula-Verlag, Wiebelsheim 2004, ISBN 3-89104-685-5 .
