Siskins and Redpolls (Focus - February)

At this time of year I keep an eye on my garden bird feeder for two rather small and easy to miss finches: the siskin and lesser redpoll. Both are drawn to the sunflower hearts, and I assume they visit when their usual food, seeds, particularly those of alder and birch trees, are becoming depleted in the wider countryside. The skin is not hard to identify. It is smaller than a greenfinch but is a similar yellow-green colour streaked with black on the wings and crest. It also has a distinctive forked tail, and a narrow beak suited to prising out the tiny tree seeds it favours. The redpoll is the same size and largely brown but for the red marking on the top of its head and down the breast.

Now, like me, I expect most readers will have struggled with spotting the difference between the common repoll, lesser redpoll and arctic redpoll. Well, there is good news. Those nice people at the International Ornithological Committee have recently decided to lump all the above into one species – the redpoll. Advances in genetics have allowed biologists to assess the genetic similarity of the birds previously considered as different species. While the birds may have slight variations in plumage, distribution, and size, genetically they are almost identical. It has been decided that this variation is just within the species, rather than representing the kind of difference which prevents interbreeding.

This makes life considerably easier for most birdwatchers although it does mean that keen twitchers have lost two species from their potential year lists. At the same time, the hooded crow – found in the north and west of the British Isles – has now been deemed to be one species with the carrion crow we see around Tisbury.

There currently seems to be quite a few changes in what is and isn’t considered a separate species. The red grouse, found in the uplands of the UK and Ireland had until recently been considered a subspecies of the willow grouse/ptarmigan found widely in northern Europe and Russia. Now it has been found to be a separate species, endemic (i.e. found nowhere else) to the British Isles.

Before this, the only endemic bird species in the UK was the scottish crossbill, which was only identified as a separate species 30 or so years ago. Its size, structure and voice are intermediate between the red crossbill and parrot crossbill and its separation is still a point of discussion. Indeed, the best clue to separating it from the other species appears to be that you see it in Scotland. However, I should imagine the Scottish Government at Holyrood House will be keen to avoid the loss of the appellation “scottish” and having the bird lumped in with the red crossbills that we can see in some local woods.

​Andrew Graham