Common crossbill (Loxia curvirostra)

Crossbills
(illustration courtesy of Dan Powell)

Common crossbills are something of a New Forest speciality bird that it’s always a treat to see.

Usually gregarious creatures, male crossbills are predominantly a subtle brick-red colour, whilst females are a mixture of olive-greens, greys and browns. Both sexes are only a little larger than greenfinches, but they always give the impression of greater size and bulk, for they are strong, muscular birds that have evolved to carry conifer cones, sometimes almost as large as themselves.
 
Crossbills can, however, be very inconspicuous when feeding high in the treetops, revealing presence only by occasional loud, metallic ‘chip, chip, chip’ call notes and a steady stream of discarded bits of cone.

Grotesquely twisted upper and lower mandibles give crossbills their extremely descriptive name. Indeed, so noticeable are the ‘crossed bills’ that Buffon, an 18th century naturalist, described them as ‘an error and defect of nature’, and ‘a useless deformity.’ Nothing, though, could be further from the truth, for they are superbly adapted to extract seeds from deep inside the cones.

Spruce and pine seeds are particularly favoured, so crossbills are most often found in places where this food supply is readily available. Indeed, presence in the New Forest was presumably very limited before the 19th century creation of extensive coniferous plantations.

In the early 1860s, though, John Wise referred to crossbills as ‘not uncommon winter birds’, and mentioned a large 1861 flock that frequented the plantations round Burley. Breeding had by then also been proved. To quote Wise: ‘Mr. Farren mentions a nest built in a fir tree in a garden near Lyndhurst, June 1858, of which the birds were shot, but unfortunately not preserved….’!

But today, crossbills may be found in any block of suitable conifers, and also in self-sown heathland pines - Parkhill Inclosure is quite a reliable site, and so are Frame Heath, Slufters, Holmsley and Milkham Inclosures, and the pines either side of the road near Beaulieu Road station.

Crossbill numbers vary from year to year, and are largely determined by the size of the cone crop in the bird’s favoured northern European haunts - in good cone years, unless the crossbill population is really high, many birds remain in Norway, Sweden, Russia and the adjoining countries, but when the crop is poor, they move further afield, searching for food.

Here, some crossbills just pass through, whilst others stay to breed, often building nests before the winter is out, high in isolated or woodland edge conifers where they live in what has been described as ‘loose, neighbourhood groups’.

References:
The Shell Guide to the Birds of Britain and Ireland: James Ferguson-Lees, Ian Willis, and J.T.R. Sharrock.
The New Forest: Its History and Scenery: John R. Wise.
The Birds of the Western Palearctic: Stanley Cramp, et al.
Hampshire Bird Reports: Hampshire Ornithological Society