MIGRATIONS OF BIRDS AT TUSKAR ROCK. 217 



by performing lengthened and disordered movements in the 

 dazzle of the rays during the night. In short, then, the three 

 species under consideration perform their migrations in the 

 vicinity of the Tuskar Light Station almost entirely by day, and 

 the Eock, not the lighthouse balcony, is the observatory whence 

 we behold their movements. 



Nocturnal Migrants observed on the Rock at Dawn. 

 In the opening pages of this paper I stated that, while my 

 primary intention was to study the migratory movements of the 

 three above-mentioned species, I also proposed, in regard to 

 several other species, to touch upon some aspects of diurnal 

 migration into which I had gained an insight during my hours 

 of watch on the Eock. Here, however, I have practically no 

 occasion to deal with Direction or other characters of flight, as 

 before detailed, because the birds which I now wish to consider 

 seldom flew across the Eock. On the contrary, they almost 

 always flew straight in and alighted, and remained for a variable 

 time, until they left either of their own accord, or because they 

 were scared by human presence or aught else. But as the 

 majority of these species also figured prominently at the lantern, 

 it seems most incumbent to consider very carefully the circum- 

 stances under which they appeared on the Eock, when endea- 

 vouring to discriminate between genuine diurnal migrants and 

 such nocturnal migrants as may have descended at dawn from 

 the lantern, round which they had been flying during the 

 previous hours of darkness. 



Birds descended from the lantern to the Eock by : (a) being 

 killed outright, (6) becoming stunned by striking the lantern 

 head on, or stupefied from being hurdled against the lantern 

 by the wind. Such birds might sustain further injuries as 

 they drop unconscious to the Eock, as fracture of a limb, 

 usually a wing ; (c) breaking or dislocating their shoulder by 

 coming in contact with some projecting object, as the pillar 

 of the balcony-rails, the hand-rings of the window-panes, &c. ; 

 {d) becoming exhausted or even fatigued from flying round 

 and round the lantern all night in a wildly excited fashion 

 as the brilliancy of the beams of light produced a derange- 

 ment of vision, at all events, temporarily or physiologically. 

 Zool. 4th ser. vol. XVII., June, 1913. s 



