182 THE ZOOLOGIST. 



THE DIURNAL MIGRATIONS OF CERTAIN BIRDS 

 OBSERVED AT THE TUSKAR ROCK. 



By Professor C. J. Patten, M.A., M.D., Sc.D. 



Intboduction. 

 Weirdly attractive and novel is the spectacle which presents 

 itself to the student of ornithology as, in his silent night patrol, 

 he watches from the dizzy heights of the lighthouse balcony 

 the behaviour of bewildered migrants as they reel and topple 

 under the mesmeric influence of the luminous beams. Equally 

 attractive, and altogether more instructive in helping one to 

 understand many features of migration which night largely 

 occludes from view, is the study of diurnal movements of birds 

 witnessed before and for some time after the first blush of dawn 

 has dispersed the gloom of night from the rugged surf-lashed 

 island-rock and its girdle of watery waste. Nay, more than this : 

 in the study of diurnal migration one discovers the key to what 

 probably would be, in a great measure, the natural mode of 

 migration in the hours of darkness, if we imagine a complete 

 absence of the numerous lanterns of lighthouses and lightships, 

 whose brilliant beams betray the presence of wave-swept rocks, 

 headlands, and shoals, beams which nightly stave off the immi- 

 nent dangers to which our ships and lives are exposed, yet 

 beams which entrap and lead to the destruction of numbers 

 of feathered voyagers. A study of nocturnal migration, as 

 the birds, allured by the treacherous dazzle of these resplen- 

 dent beams, approach the lantern to sacrifice their lives 

 by striking the glass, is a study of bird-migration in a highly 

 distorted form ; nor, indeed, is it credible that the multitudes of 

 migrants, which, like glittering hosts, career wildly about in 

 the rays, ever and anon striking the lantern, represent natural 

 assemblies, even allowing that birds are more wont to ex- 

 hibit gregarious propensities when flying in the dark. From 

 what I have beheld when standing on the balcony, I would 



