376 
BIRD-LIFE. 
was felt for many years after. Fortunately, both for 
birds and ourselves, such cases are quite exceptional; 
birds of passage are rarely mistaken in selecting the time 
of their arrival. When they leave us slowly in the 
autumn, lingering on the road and singing, we may 
almost safely predict an open winter; if they return in 
spring quickly, and in large flocks, one may count on fine 
weather, whereas, on the contrary, if they arrive in small 
bands, or singly and slowly, stopping on the road, and 
not immediately commencing to build, cold or wet may 
be expected. Thus, in the years 1816 and 1817, the 
Brambling (Fringilla montifringilla) remained with us till 
May; our native birds were very loth to build, and some, 
indeed, did not do so at all: unfortunately both years 
justified their precaution. In mild winters some of our 
birds of passage, which are usually very regular in taking 
their departure, remain with us. 
Many other things would be much more inexplicable in 
our eyes than they really are did we ignore this presenti¬ 
ment, and attribute the cause of migration solely to the 
absence of necessary food; in which case we must neces¬ 
sarily assume that the journey is not prosecuted further 
than is requisite to find sufficient nutriment; and yet 
this is not the fact: migration proper is distinguished 
from the partial wanderings, before mentioned, by this 
very circumstance. I do not, for a moment, mean to 
assert that we have explained the cause of migration by 
the acceptation of the theory of presentiment, when we 
see the Pin-tail Duck in 11° North latitude moving 
still further to the southward, a bird which only breeds 
freely in 70°, and which could exist comfortably in the 
Mediterranean, and does, indeed, pass the winter there in 
large flocks. The correctness of this special theory 
