Where are your Purps from?

I recently heard of a colour-ring sighting of a Purple Sandpiper at Godrevy Island, Cornwall, in late October 2011. This got me thinking, as the origin of the county's wintering birds has interested me since moving down here recently. The only previous recovery in the county was an Icelandic-ringed bird seen at Penzance in November 2004 and May 2005. So it was a bit surprising to find this bird had been ringed on the island of Nidingen off the southwest coast of Sweden in May 2011.

There are two distinct populations of Purple Sandpipers that winter in the UK, of birds breeding in the east (northwest Europe) and west (Canada). These populations have, predictably, rather different wintering areas, as can be seen below. The map shows the country of ringing of birds found in the UK and the predominance of Icelandic-ringed birds (I) in the north and west and Norwegian-ringed birds (N) in the east is obvious. Zoom in to see more detail and click on the map for a key to the other codes.


View Purple Sandpipers in a larger map

The two populations can be identified on biometrics though, with bill length and wing length being of most use. So where are our Cornish birds from? Well with one from Iceland and one from Norway, perhaps only biometrics will tell.