Song thrush - do rainfall levels affect plumage pigmentation?
Notes from a 1923-24 Bulletin of the British Ornithologists' Club
Colonel Richard Meinertzhagen exhibited some song thrushes from the island of Mull and made the following remarks:
Three song thrushes recently obtained in Mull show characters of being an intermediate race.
Mull being located between the mainland of Scotland and the Outer Hebrides, it is not surprising that such a form occurs.
Great interest also lies in the fact that the rainfall of Mull is also slightly less than that in the Outer Hebrides but greater than that which falls on the eastern mainland of Scotland.
This looks as though rainfall affects the density of pigment among song thrushes, but, against this, thrushes from Ireland, where the rainfall is greater than in Scotland, do not show this tendency to the same extent.
I may add that, in both the Outer Hebrides and in Mull, the thrush is perforce a heather- and ground-frequenting bird, while, in Great Britain and Ireland, the species seldom occurs far from bushes or undergrowth.
A study of song thrushes with notes on their habits from the south-west corner of Ireland would be most interesting and might throw light on the subject as it is in that locality that falls the greatest amount of rain in these islands outside mountain areas.
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