NOTES ON MIGRANTS AND MOULT 35 



perform the same spring moult as our bird, some moulting 

 completely, others not. 



Of Garden Warblers I have seventeen (29th April to 

 17th May); all are in quite fresh plumage, body, wings, and 

 tail ; this is quite explainable by examination of specimens 

 from winter quarters : thus I find that November, December, 

 and January specimens are all in very worn plumage all 

 over, but two of them (in December and on loth January) 

 had begun to moult the primaries and secondaries. February 

 birds are in full moult, body, wings, and tail, while March 

 birds are in full new plumage. Nine birds in the autumn 

 (i8th August to 2nd October) are in fresh plumage and no 

 active moult. One Barred Warbler (17th September) also 

 exhibits no moult ; this is a species which also has of course 

 a spring moult at least of the body feathers. Ten spring 

 Blackcaps (April and Ma}) show no moult and are not very 

 worn anywhere; two winter-quarter birds (December and 

 February) are rather more worn ; although this species 

 probably moults in spring, I have nothing definite to say 

 about it ; of autumn migrants, seven in early October or 

 September exhibit no moult except one (9th September) 

 which is still moulting on the chin. 



I have examined a great many Song Thrushes (both 

 races), Redwings, Blackbirds, several Ring Ouzels, and a few 

 Mistle Thrushes on spring and autumn passage, and I have 

 not seen any in moult except one Mistle Thrush which had 

 (24th February) part of the rump in quill and one Ring 

 Ouzel (i8th October) with half of its tail a quarter grown — 

 both were obviously accidental moults. Accidental loss of 

 a tail or part thereof may, as I have on several occasions 

 witnessed, delay a bird at some spot on its migration for 

 days, e.o.^ this Ring Ouzel remained in the same place some 

 days after its companions had passed on. Accidental moult 

 (which is naturally usually unilateral) must be a fairly 

 common phenomenon and one which anyone studying moult 

 must be on guard against ; to watch birds hit a lighthouse 

 and see the cloud of feathers lost without killing the bird 

 gives one an idea of at least one cause of loss of feathers to 

 which migrants are subject. 



