33 
on the migration of birds. 
works of every naturalist I have ever had access to, who had 
written on the subject, been pointed out as the haw, the fruit 
of the white thorn.* 
This is an error that has long wanted a correction, for in 
open weather they take them in very scanty quantities, and 
feed on the ground on worms and such insects as they can 
find. Although repeated examinations of the contents of the 
stomach have afforded the best proof of this, yet there is 
scarcely any need of calling in its aid in the present instance, 
as we may he convinced of the fact, by seeing them in flocks 
feeding on the ground in open fields and meadows. I do not 
deny their taking the haw and other vegetable food from the 
hedges, but they do it in so sparing a way, that I have re- 
marked, that red wings and fieldfares die through hunger 
during the long continuance of frosty weather, while the 
haws on the hedges were by no means deficient. The occa- 
sional departure of these and some other winter birds during 
a long continued frost, must be very obvious. The greater 
number disappear soon after its commencement, if it sets in 
very severely : some few are always left behind and are soon 
starved, if not fortunately relieved by a thaw. Those that 
are driven to this necessitous migration, probably pursue a 
track that quickly leads them out of the reach of frost. Of 
these flights I shall produce instances, which render it proba- 
ble that they are able even to out-strip its course. 
The approach of intense frost is often to a certainty made 
known to us by the appearance of a numerous tribe of water- 
* Cf The principal food of these birds while with us, is the fruit of the white 
“ thorn, or haws, which hang on our hedges in winter in prodigious plenty.” 
Phil. Trans. Vol. XLIV. p. 435. 
MDCCCXXIV. 
F 
