335 
Great Invasion of Crossbills in 1909. 
vast legions of Crossbills last year migrated and spread over 
the greater part of Europe, appearing even in districts where 
the species had rarely been observed before, it is difficult, 
not to say impossible, to single out any one particular 
locality as the base or centre of the movement. It is indeed 
presumable, particularly bearing in mind its extent and 
proportions, that this migration had its origin generally 
throughout a large tract of country, the coniferous forests 
of which had all been equally affected by the inclemency of 
the past winter and spring. Under the circumstances, there¬ 
fore, I think we may look upon the movement as having 
originated throughout the entire northern portion of Europe, 
and probably still farther eastward, possibly even as far as 
Siberia. 
The presence of occasional examples of the Two-barred 
Crossbill (Loxia bifasciata) among the wandering flocks of the 
commoner species, although not conclusive, would point to 
there having been at least some migration from the more 
eastern portion of North Russia and probably also from 
Asia. 
The third point to which I have alluded, viz. the possi¬ 
bility of a guiding influence which may have directed the 
course and progress of the species' movements, is, no doubt, a 
matter for conjecture. Has there been any such influence, 
or have the birds, once started on their journey in search of 
food, wandered at random from district to district, whither¬ 
soever caprice may have taken them, and after exhausting 
the supply of food in one locality, moved on to another, 
until they found a fresh store ? The latter conjecture 
is possible, and the fact of the birds remaining in certain 
localities where food was abundant for a considerable length 
of time is in favour of the argument; but, on the other hand, 
it seems hard to believe, and it is more natural, I think, to 
suppose that, as in the case of ordinary or regular migration, 
some instinct has guided the birds on their journey, and 
brought them back again safely to their homes. It is pre¬ 
sumable, at least, that most, if not all, the surviving 
wanderers will eventually return to their native home, if they 
