Scottish Crossbill
Loxia scotica

Passeriformes Order – Fringillidae Family

The Scottish Crossbill was formerly a subspecies of the Red/Common Crossbill (L. curvirostra), but it differs by a more massive, deeper and blunter bill with less curved culmen’s base.
This species is found in N and NE Scotland where it lives almost only in conifer forest of which it is endemic. It is the only terrestrial vertebrate species unique to the United Kingdom, confirmed in August 2006.
It feeds mainly on seeds of Scot pine (Pinus sylvestris) but it also takes seeds, buds and shoots of other tree species and probably some insect larvae. It nests in a bulky, cup-shaped structure placed 6-8 metres high in old Scot pine.
The Scottish Crossbill is affected by habitat degradation caused by plantations of exotic conifer species and intense grazing by red deer which prevents the regeneration of the forests. But the population is currently stable and the species is not globally threatened.

Length: 16-17 cm
Wingspan: 29-31 cm
Weight: 36-49 g

The Scottish Crossbill is very similar to the Red/Common Crossbill in plumage, but its bill is more massive.
The adult male has bright brick-red upperparts. The scapulars are browner with orange-red wash. The upperwing is blackish-brown with reddish-brown edges to coverts and flight-feathers. The rump is bright pinkish-red, but the uppertail-coverts are brown with reddish-brown fringes. The tail is blackish-brown with reddish-brown edges to rectrices.
In worn plumage, the upperpart feathers have brown centres.
The underparts are red to orange-red with greyish tinge on flanks. The undertail-coverts are whitish with brown tips and pinkish wash.

On the head, forehead to crown and nape is bright brick-red. The lores are dusky. The eyestripe and the rear of ear-coverts are greyish-brown. Rest of face is like crown.
The bill is grey to greyish-horn with pale yellowish cutting edges and crossed mandibles. The eyes are dark brown. Legs and feet are brown to dark brown.

The adult female has olive-green upperparts. Mantle and back show dark feather bases. The scapulars are slightly darker. The rump is pale olive to yellowish-green like the uppertail-coverts, but the latter have dark olive centre. Wings and tail are similar to male but they show fine, dull olive-green edges.
The underparts are olive-yellow, but breast sides and flanks may show green or grey feather bases. Belly to undertail-coverts is whitish with dark central shaft streaks. The bare parts are like on male.

The juvenile has head and upperparts pale green to olive-green with darker streaks. Mantle and scapulars are slightly darker, usually olive-green in male and brown in female. The rump is yellowish to yellowish-green with dark streaks. The uppertail-coverts are dark brown with olive fringes. Wings and tail are similar to female, but with buff tips to coverts, buffish to yellowish-buff edges and tips to tertials. The underparts are dull buffish-yellow with dark streaks, except on lower flanks and belly.
The young male acquires the adult plumage in late second winter or second summer.   

The Scottish Crossbill is found in N and NE Scotland.

The Scottish Crossbill is confined to the Highlands, a historic region of Scotland. This region is the only area to have the taiga biome with concentrated populations of Scot pine forest. This tree species is endemic to the Caledonian Forest of Scotland, the name given to the former temperate rainforest of Scotland.
The Scottish Crossbill breeds in lowland forest and stands of Scot pines (Pinus sylvestris) as well open mature plantations and remains of ancient forest trees.  
But during winter, it occurs mainly in larches (Larix) and in plantations of Pinus contorta and Picea sitchensis, or in pine woodland with heather understorey.
The crossbills has become so specialised that they can only live in conifer forests.

There are slight variations between the sound uttered by the Scottish Crossbill and the Red/Common Crossbill.
The “chip” call of the Scottish Crossbill is relatively louder, especially when the bird is excited or alarmed or before to take flight. The flight calls are deeper and coarser “tyoop-tyoop-tyoop” whereas the Red/Common Crossbill gives a ringing “jip-jip-jip”. The sounds may also vary according to the density of woodlands.

The male’s song is given from perch and in flight. It is described as a series of short phrases “tiup rrreee priooo” and often includes several “chip” notes in repeated phrases, sometimes preceded by short rattling “schweerr schweerr”.
Both male and female give a soft song described as “tip-tip-tip-toohee-toohee-tip-tip-too-hee-quik-quik”. Some louder “toop” notes are sometimes included into this sequence.  

The Scottish Crossbill feeds on seeds of Scot pine, and when they are unavailable, it also takes seeds, blossoms, buds and shoots of larch, spruce, fir, Douglas fir and beech. Some invertebrates are probably part of the diet too.
The crossbills are highly specialised thanks to their crossed mandibles allowing them to extract the seed from the pine cones. In the same way, the strong, asymmetrical jaw muscles assist the twisting movement used to extract the seed.

The Scottish Crossbill feeds in two different ways.
The bird breaks the cone from the tree, that requires a considerable effort during which it appears to make use of every muscle. Then, the cone is carried to a branch where the bird holds it firmly with the feet while it extracts the seeds with the crossed bill.
But it may also feed by moving around the cone. It obtains the seed by inserting the bill tips between the scales of the cone, before turning the bill. It uses the upper mandible or the tongue to retrieve the seeds.
The Scottish Crossbill also gleans invertebrates from branches, bark and lichens. It frequently drinks water.

It forages in pairs or in flocks of up to 20 individuals, and sometimes close to the Red/Common Crossbill flocks.

The Scottish Crossbill is usually monogamous. They nest solitary or in loose colonies.
The courtship displays start in late winter or early spring. Groups of males sing loudly in chorus. They become very aggressive towards each other.
The pair forms during winter. The courtship displays show both mates in front of each other while perched, with the wings partly open and away from the body. They touch their bills and link together while moving their heads from side to side or back and forth.
Other displays take place in the air, when the male pursues the female through the tree tops. It approaches her in circular flight with rapid wingbeats. The female adopts a crouched posture while uttering chittering calls. Her tail is raised and her wings slightly drooped and shivering, prior to copulation.  
Courtship feeding by male to female occurs from pair formation to incubation. The male also performs mate-guarding. Both adults share the nesting duties. 

The Scottish Crossbill is resident with some local dispersion related to food availability.
It flies with several rapid wingbeats interspersed with short glides.

The breeding season takes place from late January/February to June, with the laying mainly in March/April. This species produces one or two broods, depending on food resources.
The nest of the Scottish Crossbill is built by the female, sometimes helped by the male. The cup-shaped, bulky structure is made of twigs of pine, heather, grass, vegetal fibres, bark, moss, lichens, leaves, hair and feathers. It is placed in old Scot pine, 6-8 metres above the ground and high in tree crown or at the end of a branch, rarely close to the trunk.

The female lays 2-5 pale blue eggs with purplish markings. She incubates alone during 13-15 days, and she is usually fed by her partner during this period. The chicks are fed by both parents. They fledge 17-25 days after hatching and they are fed by adults for up to 8 weeks. For the first ten days after leaving the nest, their bills are not crossed and they cannot feed on seeds from pine cones.

The Scottish Crossbill has restricted range in which it may be affected by degradation of the habitat through plantation of exotic conifer species, and intense grazing from high numbers of deer, preventing the regeneration of the forest.
The population is estimated to number 8,200/22,800 mature individuals and is suspected to be stable.
The Scottish Crossbill is not globally threatened and the species is currently evaluated as Least Concern.

Fr: Bec-croisé d’Ecosse
Ang: Scottish Crossbill
All: Schottlandkreuzschnabel
Esp: Piquituerto Escocés
Ita: Crociere di Scozia
Nd: Schotse Kruisbek
Sd: skotsk korsnäbb  

Text by Nicole Bouglouan


HANDBOOK OF THE BIRDS OF THE WORLD Vol 15 by Josep del Hoyo-Andrew Elliot-David Christie - Lynx Edicions – ISBN: 9788496553682

THE COMPLETE BOOK OF BRITISH BIRDS – Written by “Royal Society for the Protection of Birds” experts - Préface de Magnus Magnusson - Michael Cady- Rob Hume Editors - ISBN: 0749509112 


FINCHES AND SPARROWS by Peter Clement, Alan Harris and John Davis – Helm Identification Guides – ISBN: 0713652039

Avibase (Denis Lepage)

Birdlife International

Birds of the World

Bird ID Nord University

A first survey of the global population size and distribution of the Scottish Crossbill Loxia scotica

The Scottish Crossbill: Loxia scotica

Species Action Plan for the Scottish Crossbill Loxia scotica In Europe

Forestry and Land Scotland

Animal Corner

Loxia scotica Britain’s Only Endemic Bird?

Scotland's Wildlife: Scottish Crossbill

The state of Scotland’s rainforest

What Bird-The ultimate Bird Guide (Mitchell Waite) 

Wikipedia, the free encyclopaedia


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