IMPORTANCE OF NEW ZEALAND BIRDS 15 
Hawks often build on top of an old nest, or use 
that of another bird, e.g. the Kestrel (Falco tinnun- 
culus), which sometimes eject jackdaws from their 
home, the uproar subsiding as soon as the deed is 
done; the birds seeming to know that they will be 
no more molested: as birds of prey go far afield 
to catch their food, in order not to reveal the where- 
abouts of their nest. It is therefore possible to see 
these pretty hawks living amidst a colony of noisy 
daws. 
Pigeons’ nests are proverbially frail but far 
stronger than would be expected; they are some- 
times used a second time by Owls in Scotland, which 
shows they must be solid to be capable of so much 
use. Ducks nearly all build on the ground, though 
the Mallard (Anas bosca) occasionally makes use of 
a tree in which to hatch out their young. The 
related New Zealand Grey Duck (Anas superciliosa) 
often nests in clumps of epiphytes high up in trees. 
Where the egg is large compared with the size of 
the parent, the chick is able to run about and feed 
itself immediately it is hatched. The Kiwi lays the 
largest egg in the world in proportion to the size of 
the bird, and has been described as laying a bigger 
egg than itself. Though in many points resembling 
the Ostriches, unlike them its eggs are smooth, not 
pitted. 
Birds like the Pigeon, which lays a small egg for 
its size, have correspondingly helpless young, which 
have to be fed and looked after for some time. 
No fixed rule can be applied to the coloration of 
eggs. The Australian Swamp Quail (Synoicus 
australis), for example, never lays two clutches alike 
in size or colouring. It may, however, be said that 
eggs are often determined by tho» nature of their 
environment. The coloration is protective, in many 
cases, aS is seen amongst those birds whose eggs 
are somewhat exposed. Many shore birds such as 
the Dottrels, Knots, ete., make an apology for a nest 
