6 STUDIES IN BIRD-MIGRATION 



place, and this, too, strange to say, is sometimes per- 

 formed by identical species on the same day and even at 

 the same hour. Another feature of importance is that 

 at the Kentish Knock and neighbouring lightships the 

 day movements equal, if they do not surpass in magni- 

 tude, those observed during the night, whereas at other 

 stations around our coasts the nocturnal movements 

 vastly exceed in extent those occurring during the day. 



As at the Eddystone in 1901, I found it extremely 

 difficult to detect small birds travelling singly or in twos 

 and threes during the daytime. The great majority — 

 nearly all of them, in fact — flew close to the water, and 

 the surface, almost always in motion, forms a most 

 unsatisfactory background against which to pick up 

 migrants, unless they are passing in large flocks. The 

 rougher the sea the more difficult is the task of observa- 

 tion, and the higher the wind the more closely do the 

 birds hug the surface of the sea ; thus, except during a 

 dead calm, many migrants escape notice, in spite of the 

 utmost watchfulness on the part of the observer. 



In connection with the movements witnessed at such 

 isolated stations, it must be remembered that these 

 observatories are mere specks in the open sea, and the 

 marvel is that one sees so much, especially during the 

 daytime. At night it is somewhat different, for then, 

 under certain atmospheric conditions, numbers of birds 

 are attracted to the lantern — many of them, no doubt, 

 being allured from afar. 



In the preparation of these results I have grouped 

 the observations under the particular set of movements 

 or problems to which they relate, reserving certain 

 information to be dealt with under the various species. 



The first migratory movements to come under notice 



