Can you identify this bird?

Q. This photo was taken by me on Lindisfarne two weeks ago, as the tide was coming in. As well as the Ringed Plovers (wonderful, maybe 100) and Dunlin, there is a bird in the middle and I would be very interested to know what it is.
Helen Beach

A. Despite looking very different to the Dunlin alongside it, this is another Dunlin. Dunlin are notoriously variable, both in terms of size and plumage, which can make ID difficult, even for the experienced! This one is particularly dark in the underbody, but examining the other two Dunlin on the rocks will reveal quite large colour differences, the rightmost bird being quite dark around the neck. Familiarity with Dunlin and all their variations can be useful, as the bird is often used by wader watchers as a “yardstick” species for picking out real rarities.