MIGRATIONS OF BIRDS AT TUSKAR ROCK. 215 



tion of the matter lends no new aid to the personal observer 

 working out the problems of night-lines in birds. But if we 

 take into consideration the wonderful speed, and, what is more 

 important, the wonderful endurance of flight in birds, then a 

 lack of knowledge among immature birds in regard to the 

 shortest route to their destination, manifestly matters but little. 

 To my mind the passage of Swallows across St. George's Channel 

 and thence north along part of the Irish coast (or, indeed, for 

 that matter, round the whole of the Irish coast), en route for the 

 African Continent, as compared with the shortest possible course, 

 is a matter of very small moment. 



Viewing the question of the migration-route of Swallows in a 

 technical rather than a general light, I think it worth while 

 laying emphasis on the fact that the initial period of emigration 

 as observed in 1901, at the Eddystone Lighthouse by Mr. Eagle 

 Clarke, viz. September 24th, corresponded very closely with the 

 date when I first saw Swallows in September, 1912, flying south 

 to south-east past Tuskar Rock, i. e. from the shore. Further- 

 more, the birds pursuing a southward course, as observed by 

 Mr. Witherby in September, 1911, appeared to do so at a later 

 date than those which he noticed flying northwards, if we 

 except one date, viz. September 11th ; and, as just mentioned, I 

 observed the same feature in September, 1912. Moreover, the 

 time in September when Mr. Witherby and I noticed Swallows 

 altering their course from north to south, though observed in 

 different years, is fairly synchronous. The south-bound birds 

 observed by Mr. Witherby in September and early October, 1911, 

 evidently did not pass the Tuskar Light-Station, for all the birds 

 seen by the light-keepers and myself at that time directed their 

 flight in the main to the north-west, sometimes, however, going 

 due north or west. And it seems that these birds headed in the 

 same direction past where Mr. Witherby was residing (Rosslare 

 strand), for they were seen by Mr. Delap pursuing this route all 

 along from Rosslare Harbour to Wexford. The ground on which 

 these two observers worked overlapped considerably, which at 

 first makes it difficult to reconcile their opposing observations, 

 but when we bear in mind the significant fact that on many 

 occasions when Mr. Delap saw birds flying north Mr. Witherby 

 made no observations, and vice versa when Mr. Witherby saw 



