506 DR. p. CHALMERS MITCHELL ON LONGEVITY AND 



however, that both average and maximum durations are con- 

 siderably better in the case of the diurnal birds of prey. No 

 intelligent anatomist can now doubt that the two groups are far 

 separate amongst birds, and one of the notable differences is in 

 the structui-e of the alimentary tract. In all the Accipitrine 

 birds, although the intestines are relatively long and arranged in 

 a complex pattern, the hind-gut and cpeca are extremely reduced, 

 and the portion of the gut in which there is the greatest 

 opportunity for intestinal putrefaction therefore has a relatively 

 very small capacity. 



Capt. Flower records only two Accipitrine birds — a Griffon 

 Vulture and an Egyptian Vulture — that are still alive after 

 12 years' duration, the maximum possible in his records. 



Mr. J. H. Gurney [loc. cit. p. 38) gives the records, of six Pelicans 

 ranging from 41 to 18 years, and the maximum durations given 

 above, ranging downwards from nearly 32 years, are all re- 

 markably high, whilst the average durations show that these 

 birds are probably the most highly viable of all the birds and 

 mammals usually kept in captiviiby. They were not provided 

 with artificial heat, but throughout the day were exposed fully 

 to the weather, whilst at night, and occasionally in very cold or 

 foggy conditions, they were shut up in a small wooden shelter. 

 As compared with other fish-eating birds, the alimentary tract is 

 relatively short and simple, and the cfeca and hind-gut are small 

 (although not so reduced as in Accipitrine birds) and uncapacious. 



Capt. Flower records one White Pelican still alive after 

 12 years. 



FregATID-?5. ^°-.°f Av.dur. Max. dur. 



Indiv. in months, m months. 



.Fre^/cito ft^'iti^a (Great Frigate-bird) ... 5 45-6 91 



It is most probable that only weak or injured examples of this 

 oceanic bird usually find their way into captivity, and the i^ecords, 

 I think, must be interpreted as showing a high viability. The 

 intestinal tract is simpler than that of Pelicans, with the hind- 

 gut and cteca more reduced. These birds have been kept in an 

 aviary with warmed interior and open-air front cages. 



