20 
THE MIGRATION OF BIRDS. 
By the Rev. A. RAWSON, M.A. 
READ with much interest Mr. Gordon’s article on the 
“ Departure of Birds ” in the October number of the 
Selborne Magazine, and his suggestion that notes 
should be taken as carefully of the departures as of the 
arrivals of our migrants. This is no doubt practicable, but I 
think there is a difficulty, not in compiling the record, but in 
drawing any conclusions from it. There is a great mystery 
about the migration of birds. Manj^ theories have been put 
forth as to its causes and its regularity, but I think there can 
be no doubt that “ food ” has much to do with it— at least, with 
the emigration, if not with the immigration, of our summer birds 
of passage. 
With regard to arrivals in spring, these consist entirely of 
old birds, which are hardier and more able to take care of them- 
selves than their progeny in autumn. It is doubtful Avhether 
these spring migrants are impelled to seek our shores through 
lack of food in the countries from which they come ; but the 
migratory fever seizes them, and off they set, whatever the 
cause may be. It is well known thac if the early arrivals 
find it cold here, and therefore insect life is kept back, they (the 
swallow tribe, certainly) disappear again for a time ; still they 
have arrived with regularity, been seen, and noted. With the 
autumnal departures things are different. Here we have both 
old and young birds, many of the latter quite incapable of a long 
flight ; and so long as a genial temperature keeps insects from 
hibernating, the food supply is kept up, and these few remain, 
though the main body may have gone. The consequence is 
that the departures extend over a considerable interval, and an 
observer must be constantly On the watch for a month or more 
for the “ last seen ” of any particular bird. 
I may instance this in the Swallow tribe. Here they begin 
to congregate on my house in the last week in August, and have 
practically gone by the middle of September; but in 1886, I 
saw one single Swallow on October 22nd, and in 1887, a remark- 
able year, many were flying about Furness Abbey on October 
7th. In 1885, at Bromley, in Kent, I saw Martins as late as 
November 16th. In the same year, at the same place, the Swift 
was seen September 8th — a late occurrence, and in the last week 
of September, 1878, my son shot the Alpine Swift on the north 
coast of Devon, several of the common species being in company 
with it. 
I have taken the Hirundines as being birds easy of observa- 
tion, but no doubt the same is true of other migrants ; they must 
have food, and owing to some peculiarity in the season, it was 
there for them, so they remained late. My opinion as to this is 
confirmed, because, in regard to my note of the very late swal- 
