Ages to which Birds live. 23 



sorts of birds that lay a good many eggs, such as the Anseres 

 and Cygni, which are kuowu to be long-lived. 



Weismanu and Oken have argued that in St. Kilda 

 [Boreray] so many young Gannets [Sula bassana) are 

 annually taken for food that, if this were not a long-lived 

 species, diminution in the stock would be observable ; and 

 the same applies to the Fulmar {Fulmarus glacialis). This 

 is in some respects rather a false style of reasoning, because 

 if there were not an annual slaughter there would probably 

 be an annual throwing off of the surplus ; but as the argu- 

 ment has been put forward it must not be passed over. If 

 it were admitted, it would apply in a less degree to Perdix 

 cinei'ea and Lagopus scoticus, which are shot by tens of 

 thousands, and also to several other birds. 



Search as we will, we hardly ever find a bird which has 

 unmistakably died a natural death, and this has been put 

 forward by some authors as a great argument for longevity. 

 For the same reason great age has been assigned to the 

 elephant, and such elephant-hunters as Sir Samuel Baker and 

 Col. Pollock declare that they have never come across the 

 carcass of an elephant. Allowing for the quick consumption 

 of the soft parts by predaceous quadrupeds and burying 

 beetles, one would at least expect to find the larger birds^ 

 skeletons occasionally, but such is very seldom the case. 



The period of a bird^s incubation seems to have something 

 to do with the length of its life, albeit the Psittaci are the 

 principal exception which invalidate this theory. Referring 

 to Mr. William Evans's '^ Table of Periods of Incubation " 

 (Ibis^ 1891, p. 57, 1892, p. 55), it will be seen that Cockatoos 

 take 21 days, Cockateels 20, Parrakeets 18, and Macaws from 

 20 to 25, to hatch. Three weeks is very little for such a long- 

 lived family as this is commonly supposed to be, compared 

 with the incubation of many birds which, according to our 

 present knowledge, do not live so long as the Psittaci ; but 

 the subject cannot be worked out without more facts which 

 we have not got at present. Among long-lived birds which 

 take a long time in incubation, the principal are : — 



