[ 3i5 3 
This circumftance, however, is by no means pe- 
culiar to the fieldfare and redwing; mod of the hard- 
billed finging birds do the fame in winter, but fepa- 
rate in fummer, as it is indeed neceflary all birds 
fhould during the time of breeding. 
I fhall now confider another argument in favour of 
migration, which I do not know hath been ever 
infifted upon by thofe writers who have contended 
for it, and which at firft appearance feems to carry 
great weight with it. 
There are certain birds, which are fuppofed to vifit 
this ifland only at diftant intervals of years ; the Bo- 
hemian chatterer and crofs -bill * (for example) once 
perhaps in twenty. 
The fadt is not difputed, that fuch birds are not 
commonly obferved in particular fpots from year to 
fear ; but this may arife from two caufes, either a 
partial migration within the verge of our ifland, or 
perhaps more frequently from want of a ready know- 
ledge of birds on the wing, when they happen to* 
be feen indeed, but cannot be examined. 
I never have difputed fuch a partial migration; and 
indeed I have received a mofl irrefragable proof of 
fuch a flitting, from the Rev. Mr. White of Selborm 
in Hampshire, whofe accurate obfervations I have be- 
fore had occafion to argue from. 
* This bird changes the colour of its plumage at different 
feafons of the year, which is fometimes red. 
The firft account we have of their being feen, is in the Ph. Tr». 
abr, Vol. V. p. 33. where Mr. Edward Lhwyd fufpedts them 
to be Virginia nightingales, from their feathers being red, and 
had no difficulty of at once fnppofing. that they had crofted the 
Atlantic., 
S S % 
