SESSION 1896-97. 





I.— MIGRATION OF THE HIRUNDINES. 

 By Mr A. B. HERBERT. 



(Read Nov. 25, 1896.) 



On the 22nd of September last, at 7.30 A.M., I noticed that the 

 air seemed very full of the swallow tribe, and on looking up 

 to a great altitude, I observed incalculable numbers coming 

 quickly into the range of vision. The atmosphere was very 

 clear, and they looked mere specks coming down, I imagined, 

 from a height where they were invisible. It at once occurred 

 to me that this was strongly corroborative of the veteran Herr 

 Gatke's statement, from his observations at Heligoland, that 

 many birds in migrating fly at such an extreme height that 

 they are almost, or perhaps cpiite, invisible. Their descent to 

 within a short distance from the ground was very perpen- 

 dicular and rapid, and they all moved off in one direction 

 towards the river Wandle. I presume it was a vast nocturnal 

 migration, and that they descended to the river either to drink 

 or to obtain a breakfast of gnats or other insects found near 

 the stream. Many in their descent came so near to me that 

 there was no difficulty in identifying the species, and all I 

 noticed were house martins (Hirundo itrbica). I would not 

 for a moment attempt to give an estimate of numbers : when 

 Herr Gatke mentions tens of thousands we may perhaps think 

 it an exaggeration, but after what I witnessed I will merely 

 remark that there was quite a cloud of birds. How much I 



VOL. III. P 



