PASSERINE BIRDS FOUND MIGRATING IN MOULT 245 



NOTES ON SOME PASSERINE BIRDS FOUND 

 MIGRATING IN MOULT. 



By Leonora Jeffrey Rintoul, F.Z.S., H.M.B.O.U., and 

 Evelyn V. Baxter, F.Z.S., H.M.B.O.U. 



The subject of moult is one on which perhaps less has been 

 written than on any other phase of bird life, and while the 

 broad facts are generally known, the minuter details have, 

 so far as we know from published information, occupied 

 but little of the attention of ornithologists. It is occa- 

 sionally stated that birds complete their moult before 

 migrating ; that this statement is not uniformly correct 

 is known to every ornithologist who has observed the 

 arrival of Waders on our shores, in late summer 

 and early autumn. The earlier arrivals of Turnstones, 

 Knots, Sanderlings, Bar-tailed Godwits, and Grey Plover 

 to mention only the more outstanding ones are often still in 

 breeding dress ; the plumage is frequently very faded and 

 shows signs of the wear and tear to which it has been 

 subjected, but the birds are still in the dress in which they 

 spent their brief summer in the Arctic solitudes of the far-off 

 tundras. While this is apparent to every field naturalist, it 

 is, we think, not generally realised that many Passerine 

 species migrate at times in a state of partial moult, this 

 being usually confined to the body feathers. We have for 

 some time been interested in the subject, and, as we have 

 had considerable opportunity of examining birds killed at 

 lighthouse lanterns while in the act of migrating, and as 

 Mr Eagle Clarke has kindly placed at our disposal the 

 large and representative collection of skins at the Royal 

 Scottish Museum, including all his Fair Isle specimens, we 

 think it may be worth while to put on record what we have 

 found. All the material examined has come either from 

 the lanterns or from stations where birds occur only on 

 migration, specially on passage. Some of the undeveloped 

 feathers may, of course, have been replacing others lost 

 through accident, but the majority of the specimens, of which 

 details are given below, were without doubt birds undergoing 



