218 ROUGH-LEGGED FALCON. 



first year, are to be met with in the proportion of fifty to one. In all 

 our other Hawks the same propensity may be looked upon as existing, 

 although some trifling variations might easily be pointed out. 



As in Nature, as well as in arithmetic, all rules that are true are 

 found to work equally well both ways, I think that it will be established 

 that the young of all such species as are wont in mature age to remove 

 farthest north to breed, will be found to tarry for the same purpose at 

 a greater or less distance from the place of their nativity according to 

 their respective ages and their increasing vigour, which may enable 

 them to undertake longer journeys than even their parents. For this 

 reason, I feel a considerable degree of assvirance in saying that the 

 young of the Jer Falcon vdll be more abundantly met with breeding 

 on the coast of Labrador in its grey plimiage, than the adult in its 

 white and slightly spotted garb, which will easily make its way to the 

 very highest latitudes. The Peregrine Falcon will of course be found 

 to act in the same manner, and this I partly established when I found 

 the lighter-plumaged birds of this species farther south than the old 

 ones, of which but a very few had stopped as it were at Labrador to 

 breed ; while, on the other hand, some twenty or more pairs of yet 

 brown- coloured birds were found with young in the rocky and moun- 

 tainous parts of that country. 



I feel assured that the principle here laid down will be found to 

 exist in reference to all birds that are destined to remove from one part 

 of the world to another, for the purpose of breeding. 



Whilst in Em-ope, where I have now spent many years, I have ob- 

 served further, that in late and cold springs the Nightingales that I 

 listened to, both in France and in the southern parts of England, were 

 by far the best singers ; whereas, on the contrary, when the winter 

 had been mild, and the spring fine, these birds were more numerous, 

 perhaps as six to one, and their songs were diversified in point of com- 

 pass and effect. I therefore inferred that in cold springs few of the 

 younger birds make their appearance in these countries, the rest re- 

 maining and breeding in warmer climates. 



What I have said respecting my having found Ducks of species 

 breeding in the Texas, which are generally known to proceed far north, 

 I look upon as another evidence of the truth of my principle. Should 

 it prove to be correct, it will no longer appear strange that the Rough- 

 legged Falcon in its old age should never have been observed in the 



