IMPORTANCE OF NEW ZEALAND BIRDS 19 
renewed in pairs, this enabling the birds to carry 
on as usual. An example of this gradual process is 
seen amongst birds of prey, which take a year to 
renew the whole of their feathers. It is said that 
single birds moult very much later than those which 
are paired. 
To give a definite rule as regards the age of birds 
is difficult. Many Parrots attain a great age, living 
to be one hundred, as do likewise Eagles and Ravens. 
The latter are said to live even to two hundred. 
Much can be ascertained on this subject by ringing 
the birds in their nests. There is no doubt that the 
majority of birds do live longer than usually thought. 
Many, however, who would otherwise attain quite a 
good age, die violent deaths. Actual sickness accounts 
only for a few birds. Cold and starvation alike 
contribute towards the heavy death roll, to say 
nothing of attacks by birds of prey. Of the Emperor 
Penguin chicks, less than thirty per cent. alone 
survive. Ducks raise huge broods, but very few 
reach maturity. Moorhens and such-like birds nest- 
ing by the water’s edge annually lose some young 
owing to these, when disturbed, springing into the 
water and being carried downstream ere their mother 
ean collect them. 
Stoats, cats and rats are all deadly enemies of 
our feathered friends, whilst in some countries the 
unfortunate birds have to deal with snakes as well. 
In many parts of the world the birds more adapted 
to conditions of settlement are crowding out the 
indigenous forms. The Sparrow (Passer domesticus) , 
in particular, has a very bad name in this respect, 
whilst in Australia the Starling (Sturnus vulgaris) 
has taken to driving out the Tree-creepers and 
Kingfishers. Skuas, which molest some sea birds 
mercilessly, would eventually exterminate them 
completely were it not for the fact that the young 
of the Skuas often tear each other to pieces or are 
snapped up by older birds, thus restoring the 
balance. (Pycraft.) 
