Winged baubles keep trees lit up
Festive decorations should have come down on Twelfth Night, but thankfully there are still plenty of trees bedecked with dazzling baubles. Take a winter walk by a sluggish river, or around a dank marsh where alders grow in profusion, and you are likely to see birds in striking shades of red and green.
Ravenous redpolls and siskins dangling from gnarled branches bring joy on the dreariest of January days.
Both these small finches have tweezerlike bills proficient at unpicking the alders’ cone-like catkins for their nutritious seeds – and such is their concentration while eating, you can get within a few feet of a feasting flock to savour their colourful markings.
Male siskins are drops of sunshine on wings, with bright yellow throats, breasts and tail markings contrasting with emerald body tones and black crowns. Females come in subtler shades of green with heavy streaking along the flanks. Redpolls are altogether more variable – and therein lies one of the most complex identification challenges for birdwatchers.
In my fledgling days as a birder, they came in three distinctive varieties – the generally brown lesser redpoll, the more grizzled mealy redpoll and the heftier, hoar-frosted Arctic redpoll, sometimes described as a “flying snowball”.
Lesser redpolls were once confined to Scotland, Wales and northern England, but commercial forestry saw them spread across the country in the 1960s.
By contrast, the mealy is a scarce annual winter visitor from Europe, while the elusive Arctic redpoll hails from Canada, Greenland and northern Eurasia and only a handful arrive here each autumn.
This winter has provided great opportunities to study the plumage differences between British lesser redpolls and good numbers of Scandinavian mealies with their greyer-toned feathers and distinctive white wing-bars.
Having been enchanted watching a troupe of redpolls performing acrobatics above my head, I thought I had the identification challenges cracked, until I was reminded of the latest genetic studies.
These show the three types of redpolls are most likely a single species, with a supergene dictating their differing size, bill shapes and plumage tones.