232 BIRD BEHAVIOUR 



flightless Owl-Parrot or Kakapo of New Zealand 

 {Stringops habroptilus), and the small, flying, but 

 otherwise very similar Night-Parrakeet of Australia 

 (Geopsittacus occidentaUs) ; and the sheep-killing 

 Kea seeihs to be active indifferently by day or by 

 night, which is one reason why its attacks on the 

 sheep are so hard to guard against. 



Lord Tavistock has also noted recently that an 

 Australian Black Cockatoo which he had flying 

 loose about the park at Woburn was often on the 

 wing after dark, though of course mere flying after 

 dark does not necessarily indicate nocturnal habits, 

 as so many migratory day-birds fly at night. The 

 New Zealand flightless Rails or Wekas (Ocydromus) 

 are active by night as well as by day, and ordinary 

 Rails are great night-fliers. Swifts are said often 

 in hot weather to soar up and stay aloft all night. 



Herons often move and feed either by day or 

 night, and Bitterns and Night-Herons (Nycticorax) 

 are true nocturnal birds ; I noticed, however, that 

 in our colony of the common Night-Heron (N. 

 griseus) at Calcutta, the birds did not seem to sleep 

 much during the day ; but the same thing can 

 be said of most Owls, only the Barn-Owls being 

 generally really asleep in the daytime, if one may 

 judge from their behaviour in captivity. Petrels 

 are nocturnal at their breeding-places, probably 

 from fear of Gulls and Crows, for out at sea one 

 sees them flying freely by day in the hottest sun ; I 

 have even seen a Storm-Petrel and a Clouded Yellow 

 butterfly flying within a few yards of each other. 



