MIGRATIONS OF BIRDS AT TUSKAR ROCK. 183 



liken the so-called " rushes " of migrants — as heedless of 

 each other's safety and their own the birds dash through the 

 rays of light in wild disorder — to the unwilling assemblage of a 

 panic-stricken crowd trying to escape from the dangers of a 

 threatened disaster. There is good reason for believing that 

 the so-called "rushes" of birds are the outcome of many con- 

 joined assemblies, mustered chiefly in the vicinity of the lantern, 

 the rays of which under certain conditions of the atmosphere 

 are rendered particularly dense and brilliant, and so detain the 

 birds. And although the migrants pass on in time from lantern 

 to lantern, having lost many of their companions en route, so 

 retarded becomes their flight under the blinding luminosity that, 

 in certain localities, especially where lanterns are numerous, 

 they are led to combine, even though unwilling, into prodigious 

 and at the same time highly artificial assemblies. Birds 

 migrating in company by day — except when held up by a very 

 dense fog — present no such features : even the aerial move- 

 ments of Limicoline birds (in which systems of flocking on the 

 wing are highly developed, and manifold aerial patterns are 

 displayed) show that the strictest discipline all the while is 

 maintained. 



The Systematic Study of Diurnal Migration. 

 In studying many problems of bird-migration, careful and 

 systematically conducted observations of diurnal movements 

 — movements not distorted, and in which the birds frater- 

 nise naturally — are of supreme importance, and it behoves 

 me at the outset to indicate briefly how I came to give special 

 attention to this part of my research. In the first place, I 

 noticed that on several occasions, when examining nooks and 

 crevices in the Eock for specimens, land-birds were making a 

 passage overhead. This feature was especially noticeable 

 during the early hours of the morning. But at first such 

 observations on my part were rather casual, and usually were 

 only made on occasions when I descended from the balcony at 

 dawn, after having been at the lantern all night. Naturally I 

 examined the Eock before turning into rest, in order to collect 

 any dead, wounded, or exhausted specimens, which might have 

 dropped from the lantern. But there was no occasion to attend 



