Great Invasion of Crossbills in 1909. 335 



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 



