22 Mr. J. H. Gurney — Comparative 



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Years. 



Cockatoo {Cacatua) 81 



Goose {Anser') 80 



Swan ( Cygnus) 70 



Raven ( Corvus) 69 



Owl (Bubo) 68 



Macaw (Ara) 64 



Heron {Ardea) 60 



Bateleur Eagle {Helotarsus) 55 



Vasa Parrot ( Coracopsis) 54 



Condor {^Sarcorhamphus) 52 



Albatross (Dioniedea) 46 



Gull (Larus) 44 



Pelican (Pelecanus) 41 



Dove ( Turtur) 40 



Oyster-catcher (ITesmatojms) .... 30 

 Emu (Dromcpus) 28 



Dr. Brelim thought that the smaller birds had a shorter 

 life than the larger ones, and some other naturalists have 

 taken up the same idea, which is not improbable; but it is a 

 theory which is mere supposition, and one which is almost 

 incapable of proof, and I only mention it as having Brehm's 

 authority. I may here quote some remarks from a corre- 

 spondent who has felt the same interest in this difficult matter 

 that 1 have, " One of the puzzles/^ writes Mr. R. M. Bar- 

 rington in litt., " of the ornithological census is the uniformity 

 with which birds maintain tbeir numbers. The Guillemot 

 with one egg does not diminish, and the Wren and Teal do not 

 seem to increase, although laying many more eggs. The mor- 

 tality seems in direct ratio to the birthrate It would 



seem that, broadly speaking, a bird which lays one egg must 

 live longer than a bird which lays ten, if they both breed 

 once annually." 



Whether " age " is or is not the solution of this puzzle is 

 a difficult question to answer, — there is no species of Duck 

 in my list older than 29, and as to Wrens and Guillemots we 

 know nothing. The Guillemot has probably few enemies, 

 and the Wren and Long-tailed Titmouse cannot have much 

 to contend with. It looks as if Mr. Barrington's suggestion 

 was right, yet it must be remembered that there are several 



