Weatherwatch: The unpredictable waxwing

Of all the birds that visit us each winter, waxwings are surely the most sought after. Partly this is the result of their appearance: that delicate, soft, buffish-brown plumage, with the little crest of wispy feathers on top of the crown; their plump outlines as they flock together on a winter's day; and most of all, the blobs of red on their wingtips, so like old-fashioned sealing-wax, that give the birds their name. But the waxwing's aura also derives from its unpredictability: in some years there may be tens of thousands, in other years hardly any. The waxwing is an irruptive species, rather than a truly migratory one: a wanderer, rather than a regular visitor. When waxwings do come in plentiful numbers, from their breeding grounds in Scandinavia and western Siberia, it is often taken to be an indication of a hard winter to come. Just as with ducks, geese and swans that winter here, both ancient folklore and modern media promote the same, erroneous belief that the birds have fled southwards in order to avoid hard weather. So, the argument goes, snow and ice are on the way. It's a nice theory, spoilt by one little fact. Waxwing irruptions are not related to the weather at all, but to a combination of breeding success and food shortages. If a good nesting season is followed by a shortage of berries, the waxwings will come in their thousands; if breeding success has been poor, and berries are plentiful, they will not.