RELATIVE VIABILITY IX MAMMALS AXK BIRDS. i.>13 



AnSERIX.E (co?li.)- ^■°;.'*f Av. dur. Max. dur. 



^ ' Indiv. in inontlis. ni moiitlis. 



Anser erythroims {lAt\\Q Goose) 2 174 289 



A. indicus (Bar-headed „ ) 8 124 261 



A.segetiom (Bean „ ) 2 26-5 49 



£ernicla, whole genus ' 61 36'3 142 



B. brenta (Brent Goose) 32 17 66 



jB. canadensis (Canada ,, ) 14 44 111 



B.hutchmsi (Hutchins' „ ) 2 86 119 



B. leucopsis (Bernicle ,, ) 12 61 131 



B.ruficolUs (Red-breasted,, ) 1 142 142 



Nesochen sandvicensls (Sandwich 9 50 95 



Island Goose) 



Chloepliaga, whole genns 1 20 32 169 



G. magellanica (Upland Goose) 83 25 111 



C. melanoptera (Andean ,, ) 7 17 39 



C . poiiocephala (Ashy-headed ,, ) 8 54*5 169 

 G.TtMdiceps (Ruddy-l^eaded „ ) 22 56 162 

 Chenonetta juhata (Maned ,, ) 21 62 187 



Geese are popularly reputed to have a veiy high potential 

 longevity; Mr. J. H. Gurney {loc. cit. p. 39) mentions, on the 

 somewhat doubtful authority of Willughby, a domestic Goose, 

 80 years old, and on more exact authority a Cereopsis of 33 years 

 and a Bernicle Goose of 32 years. The highest figure on my list 

 is 24 years for a Little Goose ; but the maximum and average 

 durations (the latter in many cases are lowered by the inclusions 

 of broods of goslings) show that these birds have a high viability. 



AiSTATTisr^ No. of Av. dur. Max. dur. 



AJSAilJN^. jj^ijj^_ ill months, in months. 



Dendrocygna, whole genus 99 30 242 



D. arhorea (Black-billed Tree-duck)... 6 11 53 

 D.firciiata (Wandering „ „ )... 14 22-5 66 

 D. autumnalis (Red-billed ,, ,,)... 32 42 242 

 D.eytoni (Eyton's „ „ )... 2 27-5 29 

 D.fidva (Fulvous „ „ )... 5 44 76 

 D.javanica (Indian ,, „ )... 8 18 48 

 D. major (Larger „ „ )... 11 24 57 

 D. viduata (W]i\te-ia,ced „ „ )... 21 26 57 

 Ghenalop>excegyptiaca(EigY^tisin.Goo%e) 16 34 128 



G. jitbatus (Orinoco Goose) 14 27 82 



T«(ior)i«, whole genus 109 40 214 



T.casarca (Ruddy Sheldrake) 22 42 214 



T. cornitta {Qovaxaon „ ) 31 23 111 



T. tadornoides (Australian „ ) 15 52 1 86 



y. ^'ar^e^afa (Variegated ,, ) 41 47 172 



^?ias, whole genus 117 36"5 319 



A.hoscas " (Wild Duck)... 19 49 217 



A.cristata (Crested „ )... 2 72-5 112 



A.obscura (Dusky „ )... 5 93 146 



A. poecilorhyncha (Spot-billed ,, )... 37 33 127 



