Thanks for that; very interesting paper. It would be interesting to know whether these birds take a similar migration route back to breeding grounds in the spring, or whether they move North to Europe and then across to Greenland. This would correlate with larger numbers of leucorhoa recorded in Britain in spring, and with the fact that, according to the paper, this subspecies has only been recorded on Atlantic islands (Azores, Madeira, etc.) in autumn.
So it appears that the opposite if true of my previous knowledge in that, to a certain extent, Greenland Wheatears are more regular in Britain in spring than in autumn...thanks for correcting me.