n It must be said that the twite is nothing much to look at. It is like a little linnet stripey brown with a straw coloured bill. Even the flush of pink on its rump is only visible at close quarters. Linnets and redpolls, its closest relations, look jazzy by comparison. But the twite is one of the most interesting of Scotland's birds for one reason our population, which breeds on high upland grasslands and winters on low coastal saltmarshes, extends into the northern corner of England the the south-west edge of Norway. If you wanted to find twites anywhere else, you'd have to go to Kurdistan or 10,000ft up in the Himalayas. That's the sort of country highland Scotland really is.

What is the story behind this? The answer is global warming. The scattered populations of twite are left over from the ice age, one left at the edge and one at the top of the western palaearctic

as the world's temperature rose. So far, so natural, but it is clear that the range and numbers of twite are declining steadily. Is it because of greenhouse gases that twite are no longer so common on the whalebacks of Orkney and Shetland? We'd need a longer historical record than we have to be sure, but we'd better keep good records from now onwards.

For the time being, the twite is not a rare bird. Their paths have crossed mine on a row of fence posts on Canna and bathing in the burn that runs by the edge of the saltmarsh at the back of the bay here. Still, I'd like to see them in Kurdistan and the Hindu Kush as well.