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ROUGH-LEGGED FALCON. 



Falco lagopus, Gmel. 



PLATE CCCCXXII. Adult Male and Young, 



During the many years which I have spent in the woods, with the 

 view of becoming acquainted with all that refers to that wonderful 

 phenomenon — the desire in birds to migrate, my observations have been 

 numerous, as have been the thoughts suggested by them. Like many 

 others, I of course first observed that young birds reared in high lati- 

 tudes exhibit a greater propensity to remove far southward than their 

 parents, as if their more tender nature rendered it necessary for them 

 to seek climates, in which food and genial warmth are to be found for 

 the support of their weak constitution. That this is not the case ge- 

 nerally I am pei'fectly aware, for Swallows and many other birds, which 

 are delicately organized, find it necessary to remove far southward. 

 Yet the young of these species are in my opinion subjected to rules, 

 which I will presently lay before you. 



Some species there are of which the old birds rarely if ever abandon 

 the countries in which they have been wont to reproduce, after they 

 have acquired their full firmness of constitution. Such are the Jer 

 Falcon, the Peregrine Falcon, and the species now under considera- 

 tion. The old Jer Falcon, for instance, which is found breeding in 

 the most northern latitude, seldom removes farther southward than 

 Labrador, where it also occasionally breeds, whilst even its young do 

 not advance beyond the northern parts of the State of Maine. The 

 old Peregrine, being less able to overcome the difficulties which would 

 beset it in winter, not unfrequently proceeds southward as far as 

 South Carolina, whilst its young are now well known to spend that 

 season in many parts of South America. 



Now, what I have said regarding these two species seems to apply 

 equally to the Rough-legged Buzzard, Falco lagopus, of which very few 

 individuals in the plumage indicative of the adult state are found far- 

 ther south than the State of New Jersey, where the young birds of the 

 same species, in the most extraordinarily diversified plumage of their 



