528 BR. p. CHALMERS MITCHELL ON LONGEVITY AND 



duration on my list is a Common Crane which hved in the Gardens 

 for nearl)^ 43 years, another of the same species with a duration 

 of 27| years, and a Mantchurian Crane of 25| years. It is clear 

 that these large birds have a very high potential longevity. The 

 alimentary tract is relatively very long and of narrotv calibre, 

 but the cfecaand hind-gut are by no means capacious in proportion 

 to the whole tract. In the period to which the iigures relate, 

 the Cranes were kept in an open-air paddock, a few being taken 

 indoors in winter. The maximum durations, and the average 

 durations, ranging from nearly three years upwards, show thnt 

 these birds have a high viability. 



ET-Tn^-r.xr^TT^ -r^ No. of Av. dur. Max. duv. 



LIlYPYGIDiE. T 1- • ,, • ,1 



indiv. in montlis. in months, 



E uri/pyga helias (iiun-hittern) 11 48 114 



Ehinochetus juhaius {K.?\gy\) 6 137 196 



I do not know of any published figures relating to the longevity 

 of the isolated birds here placed together. The individual examples 

 of the Sun-bittern differed considerably in duration : all but one 

 of the six Kagus lived at least 9 years in the Gardens, the 

 maximum duration being over 16 years. They were kept under 

 similar conditions, in an aviary with warmed retreats and access 

 to open air. The maximum dura,tions and average durations 

 sliow that both have a high potential longevity and viability in 

 proportion to their size, but that the Kagu is hardier than the 

 Sun-bittern. In each case the alimentary tract is, relatively to 

 the size of the bird, rather long, but the posterior region and 

 cteca are uncapacious. 



ArAMID^. ^"-P^ Av.dur. Max. dur. 



Indiv. in montlis. m months. 



Aramus scolopaceus (Scolopaceous 19 9 



Coulan). 



I cannot draw any conclusion from the single example of this 

 bird. From the structure of the alimentary tract, I am disposed 

 to regard this bird as less viable than Cranes, Bustards, Sun- 

 bitterns and so forth. 



Summary of Alectorides. 

 Most naturalists would agree that the association of the birds 

 here grouped as Alectorides (following the Society's Vertebrate 

 List) is not intimate. It is quite plain that within the assemblage 

 there is no good correlation between size and longevity and 

 viahility. The Cranes, it is true, show the longest durations and 

 very good averages, but the Kagus, which are much smaller, are 

 nearly as good, whilst the Bustards, which are large and bulky 

 birds, are much worse. If we make, so to say, a correction for 

 size, discounting the expected greater longevity of the larger 

 forms, then the birds in the assemblage might be arranged as 

 follows, in the order of good to less good viability — Kagus, Cranes, 

 Sun-bitterns. Cariamas, Trumpeters, Bustards generally, and 

 lowest of all Houbara Bustards. 



