MancJiester Memoirs^ Vol. xlvi. (1902), No. V^. 11 



flight. This character stands in direct correlation with the 

 absence of predacious mammals. The power of flight 

 being no longer required as a means of escape from their 

 enemies, some of the birds have given up expending 

 their energies in that direction, living and feeding on or 

 near the ground. The wings of these birds, offering no 

 special advantages to their possessors, have not been 

 preserved by natural selection, and have to a greater or 

 less extent degenerated. The disappearance of the wings 

 appears to have been complete in the gigantic New 

 Zealand Moas, now extinct, and has been carried to 

 varying degrees in the Kiwis {Apieryx), rails {Notornis, 

 Ocydromus) and great ground parrot or Y^zk.2,'^o{^Stringops). 

 Now that numerous predacious mammals, such as dogs, 

 cats, weasels, &c., have been introduced into these islands 

 by the agency of man, the flightless birds are paying with 

 their lives for their long immunity from the struggle for 

 existence, and will, unfortunately, soon become extinct 

 except where specially protected. 



The avian fauna of the Chatham Islands is, like the flora, 

 characterized by a large proportion of peculiar forms and 

 by striking deficiencies as compared with New Zealand, 

 though the general characters are distinctly Novo- 

 Zealandian. The flightless rails are represented by the 

 diminutive Cabalus vwdestus and NesoLimnas dieffenbachn. 

 The distribution and extinction of Cabalus modestus are 

 extremely instructive ; found only on one or two rocky 

 islets in the neighbourhood of Pitt Island, it affords one 

 of the best examples of a restricted area of distribution, 

 while its extermination on Mangare, its best known 

 habitat, seems to have been largely due to the intro- 

 duction of cats. 



The kiwis and kakapo of New Zealand appear never 

 to have made their way to Chatham Island, where the 



