296 



Linnean Society. 

 May 5. 



[May 5, 



The Lord Bishop of Norwich, President^ in the Chair. 



Read a letter " On the Migration of the Swallows," addressed to 

 the Secretary. By Thomas Forster, Esq., M.D., F.L.S. &c., dated 

 Bruges, May 2nd, 1846. 



The object of this note is to show, not only that the four British 

 species of Swallows migrate, but also that their migration is pro- 

 gressive through Europe to Asia and Africa. The first table is stated 

 to have been compiled from the recorded observations of naturalists 

 and others, copied on the spot during an extensive tour through 

 Europe in the years 1833, 1834, 1835 and 1836. Dr. Forster states 

 that he is satisfied that numerous flights of the several species an- 

 nually arrive at the end of February and beginning of March in Sicily, 

 Italy and the Islands of the Mediterranean, from Africa. Of these 

 a portion proceed after a few days' rest towards the north, leaving 

 colonies in difl^erent places as they advance, until they reach their 

 most northern destination in Europe. In autumn they retire in the 

 same manner, and their numbers appear. prodigiously increased in 

 particular places where they halt and rest for days before the phalanx 

 again takes wing. This, Dr. Forster states, is also the case with 

 Quails, with the Mountain-Finch, and with many of the Warblers. 

 Particular places seem to be favourite resorts as resting-places to 

 particular species, as Pisa for example to the Swift, the Campagna 

 and Southern Italy to the Martin. When an early spring has oc- 

 curred in the S. of Europe, these birds have made their appearance 

 earlier, as if they had been capable of inferring an earlier season 

 northwards. 



Table I. 



Mean time of Arrival. 



In their recession in autumn they observe nearly the same relative 

 times, with the exception that the Swifts migrate much earlier in 

 Flanders than they do in Kent and Sussex. They are often gone on 

 the 1st of August, and always about the 5th, whereas they remain 

 in England until about the 15th. 



