MIGRATIONS OF BIRDS AT TUSKAR ROCK. 219 



making a very careful discrimination between loss of feathers 

 due to moult, and loss of feathers from a circumscribed spot due 

 to the bird striking incidentally against the glass.* I have 

 collected dead specimens, of various species, in which the loss of 

 feathers bore evidence that the birds met their fate by being blown 

 forcibly against the lantern. 



So much, then, for the behaviour of nocturnal migrants 

 which descended from the lantern at dawn and tarried on the 

 Eock, and so much for the methods adopted in seeking to obtain 

 objective evidence in regard to the circumstances under which 

 such migrants appeared on the Eock. 



Diurnal Migrations of Chaffinches, Greenfinches, and 



Grey Linnets. 

 Concerning birds which may have arrived directly on the 

 Eock in daylight irrespective of the presence of the Lighthouse, 

 it is best to examine the question from the following points of 

 view : (a) the demeanour of the bird itself ; (b) the time of day 

 when the bird was seen ; (c) the condition of the weather not 

 only on the day of the bird's arrival, but also during the pre- 

 ceding and succeeding nights ; {d) the presence of the bird on 

 the Eock associated with the presence or absence of migrants of 

 its own species at the lantern during the immediate preceding or 

 succeeding hours of darkness ; (e) the evidence obtained from an 

 examination of the dead body. It will be seen that in some 

 cases there is very little difficulty in settling the question at 

 issue ; in other cases it is well not to be too positive. Of species 

 which obviously migrate by day as well as by night, I first refer 

 to the Chaffinch. This was a bird which I observed and obtained 

 far more frequently by day than by night ; I did not see one 

 tame or listless bird — all were bright, lively, and rather wild. 

 Chaffinches arrived at various hours in the day, and owing to 

 the fact that on alighting they invariably uttered their shrill 

 alarm-note, which I could usually hear when in my room, it was 

 not difficult to set down the hour of their arrival. I seldom saw 

 this bird at first dawn as one would have expected, had it been 

 at the lantern the night before. In support of the view that 



* Vide article on " The Dartford Warbler in Ireland," ' Irish Times,' 

 Dec. 26th, 1912, pp. 5 and 6. 



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