APPENDIX. 



37 



A golden eagle which ' died at Vienna in the year 1719, had 

 been captured 104 years previously ' (Brehm, ' Leben der 

 Vogei; p. 72). 



A falcon (species not mentioned) is said to have attained an 

 age of 162 years (Knauer, ' Der Naturhistoriker,' Vienna, 1880). 



A white-headed vulture which was taken in 1706 died in the 

 Zoological Gardens at Vienna (Schonbrunn) in 1824, thus living 

 118 years in captivity (1. c). 



The example of the bearded vulture, mentioned in the text, 

 is quoted from Schinz's ' Vogel der Schweiz,' p. 196. 



The wild goose must live for upwards of 100 years, according 

 to Naumann (I.e., p. 127). The proof of this is not, however, 

 forthcoming. A wild goose which had been wounded reached 

 its eighteenth year in captivity. 



Swans are said to have lived 300 3^ears (?), (Naumann, I.e., 

 p. 127). 



It is evident that observations upon the duration of life in 

 wild birds can only rarely be made, and that the}^ are usually 

 the result of chance and cannot be verified. It is on this 

 account all the more to be desired that every ascertained fact 

 should be collected. 



If the long life of birds has been correctly interpreted as 

 compensation for their feeble fertility and for the great mor- 

 tality of their young, it will be possible to estimate the length 

 of life in a species, without direct observation, if we only know 

 its fertility and the percentage of individuals destroyed. This 

 percentage can, however, at best, be known only as an average. 

 If we consider, for example, the enormous number of sea birds 

 which breed in summer on the rocks and cliffs of the northern 

 seas, and if we remember that the majority of these birds lay 

 but one, or at most two eggs yearly, and that their young are 

 exposed to very many destructive agencies, we are forced to 

 the conclusion that they must possess a very long life, so that 

 the breeding period may be many times repeated. Their 

 number does not diminish. Year after year countless numbers 

 of these birds cover the rocks, from summit to sea-line ; mil- 

 lions of them rest there, and rise in the air Hke a thick cloud 

 whenever they are disturbed. Even in those localities which 

 are every year visited by man in order to effect their capture, 

 the number does not appear to decrease, unless the birds are 



