- Common Crossbill
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Common Crossbill 
Male Common Crossbill 
Female Common Crossbill Conservation status Scientific classification Kingdom: Animalia Phylum: Chordata Class: Aves Order: Passeriformes Family: Fringillidae Genus: Loxia Species: L. curvirostra Binomial name Loxia curvirostra
Linnaeus, 1758The Common Crossbill (Loxia curvirostra) is a small passerine bird in the finch family Fringillidae. It breeds in the spruce forests of North America, where it is known as Red Crossbill, as well as Europe and Asia; some populations (possibly different species) breed in pine forests in certain areas of all three continents, and in North America, also in Douglas-fir. It nests in conifers, laying 3–5 eggs.
This crossbill is mainly resident, but will regularly irrupt 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, particularly the various spruce species, and the unusual bill shape is an adaptation to assist the extraction of the seeds from the cone. Some populations, which may be different species, also feed on Douglas-fir and various pine species.
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. However, the South Hills Crossbill, occurring in the South Hills and Albion Mountains in Idaho has recently been described as a new species (Loxia sinesciuris). It is virtually identical to the Red Crossbill differing slightly in body dimensions and calls and shows a very low degree of hybridization with the Red Crossbill.[1]
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 or chup 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 with different calls, which rarely if ever interbreed. These forms also vary in terms of bill size and structure, and specialise on the seed cones of different species of conifer. Few ornithologists seem inclined to give these forms species status at present.
Some large-billed, pine-feeding populations currently assigned to this species in the Mediterranean area may possibly be better referred to either Parrot Crossbill or alternatively to new species in their own right, but as yet, research into them is still at a very early stage. These include Balearic Crossbill L. curvirostra balearica and North African Crossbill L. curvirostra poliogyna, feeding primarily on Aleppo Pine (Pinus halepensis); Cyprus Crossbill L. curvirostra guillemardi, feeding primarily on European black pine (Pinus nigra); and an as-yet unidentified crossbill with a Parrot Crossbill-size bill feeding primarily on Bosnian Pine (Pinus heldreichii) in the Balkans. These populations also differ on plumage, with the Balearic, North African and Cyprus races having yellower males, and the Balkan type having deep purple-pink males; this however merely reflects the differing anthocyanin content of the cones they feed on, as these pigments are transferred to the feathers.
Diversity
Distinct Eurasian Common Crossbill populations:
- Balearic Crossbill, Loxia curvirostra balearica
- Associated with Aleppo Pine Pinus halepensis
- North African Crossbill, Loxia c. poliogyna
- Associated with Aleppo Pine Pinus halepensis
- Corsican Crossbill, Loxia c. corsicana
- Associated with European Black Pine, Pinus nigra
- Cyprus Crossbill, Loxia c. guillemardi
- Associated with European Black Pine, Pinus nigra
- Crimean Crossbill, Loxia c. mariae
- Associated with European Black Pine, Pinus nigra?
- Luzon Crossbill, Loxia c. luzoniensis
- Associated with Khasi Pine, Pinus kesiya
- Annam Crossbill, Loxia c. meridionalis
- Associated with Khasi Pine, Pinus kesiya
As with Parrot and Scottish Crossbills, all of the above are fairly sedentary forms associated with hard-coned Pinus species. The following are more associated with the softer cones of spruce and larch:
- Altai Crossbill, Loxia c. altaiensis
- Associated with spruces
- Tien Shan Crossbill, Loxia c. tianschanica
- Associated with Schrenk's Spruce Picea shrenkiana
- Himalayan Crossbill, Loxia c. himalayensis
- Associated with Himalayan Hemlock Tsuga dumosa
- Japanese Crossbill, Loxia c. japonica
North American Red Crossbill subspecies list based on biometrics:
Loxia c. percna specimen
- Newfoundland Crossbill, Loxia c. percna Possibly extinct
- Lesser Crossbill, Loxia c. minor
- Sitka Crossbill, Loxia c. sitkensis
- Loxia c. neogaea
- Rocky Mountain Crossbill, Loxia c. benti
- Sierra Crossbill, Loxia c. grinnelli
- Bendire Crossbill, Loxia c. bendirei
- Mexican Crossbill, Loxia c. stricklandi
- Central American Crossbill, Loxia c. mesamericana
- South Hills Crossbill (described as new species (Loxia sinesciuris) in 2009)[1]
Jeff Groth's classification of North American Red Crossbill forms based on call-types:
- Type 1, corresponds with Loxia c. neogaea
- Recorded on Tsuga species, Picea glauca, Pinus strobus
- Type 2, corresponds with Loxia c. benti/grinnelli/bendirei
- Recorded on Rocky Mountains Ponderosa Pine Pinus ponderosa scopulorum in the west and in various Pinus species in the east
- Type 3, corresponds with Loxia c. minor and Loxia c. sitkensis (sitkensis is probably a junior synonym)
- Recorded on Western Hemlock Tsuga heterophylla
- Type 4, corresponds with Loxia c. neogaea
- Recorded on Douglas Fir Pseudotsuga menziesii
- Type 5, corresponds with Loxia c. benti/grinnelli/bendirei
- Recorded on Lodgepole Pine Pinus contorta latifolia
- Type 6, corresponds with Loxia c. stricklandi
- Uses Pine species in Section Trifoliae
- Type 7, corresponds with Loxia c. benti/grinnelli/bendirei
- In terms of diet this type is possibly a generalist
- Type 8, corresponds with Loxia c. percna
- Uses Black Spruce Picea mariana
- Type 9, corresponds with South Hills Crossbill
- Isolated population of Lodgepole Pine Pinus contorta latifolia
Summers' list of European Common Crossbill forms (with Parrot & Scottish) based on Flight/Excitement calls:
- 1A, corresponds with "British" Crossbill
- 1B, corresponds with "Parakeet" Crossbill
- 2B, corresponds with "Wandering" Crossbill
- 2D, corresponds with Parrot Crossbill Loxia pytyopsittacus
- 3C, corresponds with Scottish Crossbill Loxia scotica
- 3D, corresponds with Balearic Crossbill
- 3E, corresponds with North African Crossbill
- 4E, corresponds with "Glip" Crossbill
- 5D, corresponds with Cyprus Crossbill
"The Sound Approach's" classification of European Common Crossbill types based on call-types:[2];
- "Wandering" Crossbill (Type A - flight call "Keep")
- "Bohemian" Crossbill (Type B - flight call "Weet")
- "Glip" Crossbill (Type C - flight call "Glip")
- "Phantom" Crossbill (Type D - flight call "Jip")
- "British" Crossbill (Type E - flight call "Chip")
- "Scarce" Crossbill (Type F - flight call "Trip")
- "Parakeet" Crossbill (Type X - flight call "Cheep")
References
- ^ a b Benkman, Craig W.; Smith, Julie W.; Keenan, Patrick C.; Parchman, Thomas L.; Santisteban, Leonard (2009). "A New Species of the Red Crossbill (Fringillidae: Loxia) From Idaho". The Condor 111 (1): 169–176. doi:10.1525/cond.2009.080042.
- ^ Introduction to vocalizations of crossbills in north-western Europe
- Bangs, Outram (12 October 1932). "Birds of Western China Obtained by the Kelly–Roosevelt Expedition". Field Museum of Natural History Publication, Zoological Series 18 (11): 343–379. http://www.biodiversitylibrary.org/page/2826634.
- "Loxia curvirostra". IUCN Red List of Threatened Species. Version 2006. International Union for Conservation of Nature. 2004. http://www.iucnredlist.org/apps/redlist/details/53487. Retrieved 12 May 2006.
Categories:- IUCN Red List least concern species
- Loxia
- Balearic Crossbill, Loxia curvirostra balearica
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