Age irf' Northern Birds. 00 



proportion seems to be as one to twenty, which increases or dimi- 

 nishes according as the bird is larger or smaller. It is evident 

 that aquatic birds live long in proportion to their short youth, 

 from the immense number of individuals in the north, although 

 most of the species are monogamous so exclusively, that both 

 male and female share the labours of hatching, &c. when there 

 is but one fruitful ^g'g for a whole summer ; and more than the 

 half of the species which breed in Iceland, and of the young 

 birds, are annually taken away by the inhabitants. More than 

 20,000 or 30,000 young of the Fulmar ( Procellaria glacialis), 

 are annually taken on the Westmannoe Islands alone, which 

 must be the product of from 40,000 to 60,000 old ones, without 

 their numbers suffering any apparent diminution. And although 

 the majority of the young (Mormon fratercula) are every year 

 taken from the holes, as well as numbers of the adults, yet every 

 year the rocks are covered with birds, as if nothing had happen- 

 ed. The same is the case with the Ur'ia Bnmnichii, troile, 

 razorbill (Alca tarda), and Larus tridactylus, on Grimsoe ; with 

 the eider-duck on Widoee ; and the other species of Anas at 

 Myvatn, which seem in fact yearly to increase in numbers, al- 

 though regularly the natives fill several boat-loads with their 

 eggs. It would be impossible, in these circumstances, to pre- 

 serve the species, if the same individual did not continue to pro- 

 pagate its species for a long succession of years. 



We have just observed that the advance of old age in birds is 

 marked by no peculiar appearances. In many of the mammalia, 

 as the horse, the hair becomes white with age, or falls out alto^ 

 gether, as I have seen in the Phoca harbata. The teeth become 

 blunted, which is a mean of recognising the age of many of our 

 domestic animals. Such does not happen with old birds ; their 

 feathers retain the hues which they possess in the adult state; 

 nor do their bill or claws become perceptibly blunter. Some 

 ornithologists even maintain that the unusually white colour of 

 some individuals, in species where this is not the hue, is a sign 

 of old age, or at least of their being beyond the age for propa- 

 gation. I cannot, however, concur in this idea, but think that 

 it is not a variety depending upon age, but a regular albino. 

 The white varieties of the buzzard, swallow, and starling, exist 

 even in the young while in the nest. Horrebow asserts the 



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