Common Crossbill Totally Explained

Everything about Red Crossbill totally explained

The 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's known as Red Crossbill, as well as Europe and Asia; some populations (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 erupt 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 but also some populations (different species?) in Douglas-fir and various pine species, 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's 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 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.

Common Crossbill 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:

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 (no scientific name) 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. sitkensis and Loxia c. minor

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

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:

"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")Further Information

Get more info on 'Red Crossbill'.

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