The Beast from the East brought an unexpected gift; a brambling turned up in the mist net in my back-garden, writes.
Having been ringed and measured, the visitor was soon on the wing again, the numbered aluminium ring on its right leg asking any finder to inform the British Museum, London.
At first glance, bramblings resemble chaffinches, but the males have scruffy grey-black heads, rather than smooth grey ones, and the bills are yellow in winter. The flanks of both sexes have dark spots, but the really conspicuous field mark is a white stripe on the rump, noticeable when the bird flies. It’s worth scanning flocks, roaming the countryside in winter, for individuals displaying this tell-tale feature.
Despite its name, the brambling doesn’t frequent blackberry bushes. William Lockwood, of Reading University, suggested that “brambling” comes from “brandling”, meaning a young trout or salmon. The spots on the bird’s plumage resemble those found on the fish. “For rose-moles all in stipple upon trout that swim,” wrote Gerald Manley Hopkins.
These seed-and-berry eaters spend the summer in mixed birch and conifer forests from Norway through Siberia to Kamchatka at the eastern extremity of Asia. Such sub-Arctic regions become so cold and dark in winter that the entire brambling population must migrate south each autumn. Some flocks travel as far as Spain and Greece.
Enormous numbers are recorded occasionally. Alfred Schifferli calculated that a hundred million bramblings visited Switzerland during the winter of 1950-51. Other ornithologists however, disputed the claim, estimating that there were between 4m and 10m. Schifferli reported that up to 300,000 bramblings fed together in a 4ha area of forest; five to eight birds per square metre. Twenty million bramblings and starlings roosted regularly together at a site in Southwest France during the 1980s.
William Thompson wrote that “thousands remained for a week at Elm Park (Co Armagh) in March 1844”. We have “brambling winters” from time to time but the numbers visiting Ireland vary and few flocks venture to the West of the country.
Known in Aberdeen as Scottish chaffinches, bramblings gorge themselves on mast. Ireland has some beech stands, but the tree isn’t native, which may be why our island isn’t a popular destination with these migrants. Breeding was recorded for the first time in Scotland in 1920 and a pair, or two, nests there occasionally. Bramblings have been seen in Ireland during the breeding season. Robert Ruttledge reported a misguided one spent a week on Skellig Michael in July. However, no nest has ever come to light here.
Although territorial, males seem more concerned to keep rival suitors away from their females than to protect their patches. Bramblings and chaffinches are closely related, their lifestyles are similar and they flock together in winter, when pair-bonds are formed. Mixed marriages are only to be expected and pairings with chaffinches occur occasionally. A male brambling fed the nestlings of a chaffinch pair in Scotland, all three adults defending the nest against intruders.
Some wading birds have evolved separate northern and southern species; golden plovers breed as far south as Ireland, while their grey plover cousins nest beyond the Arctic Circle. Black and bar-tailed godwits, redshanks and greenshanks, curlews and whimbrels, are other examples of this trend. The sequence of ice ages over the last 2m years probably separated populations from each other. Each segment would have followed its own evolutionary path, eventually becoming reproductively isolated and autonomous.
The brambling-chaffinch split may have a similar history, bramblings having adapted to the more austere habitats to the North and East, while chaffinches became attuned to the milder European environment.