208 NEW ZEALAND NATURE-STUDY BOOK 
in continual danger. Such eggs are laid by sea-birds and 
others which choose for a nesting place rocky ledges or 
even the bare ground. The ovoid shape then helps to 
prevent the egg from rolling out of the nest. 
Size and what it teaches. Not only do eggs vary 
greatly in shape, but the size or volume of the egg also 
differs considerably ; and by this is meant not so much 
that large birds produce large eggs and small birds the 
reverse—conditions we would obviously expect—but that 
birds of the same size are often found to lay eggs differing 
greatly in volume. 
Asarule the young bird which comes from a large or 
relatively large egg laid in a roughly-constructed nest is 
covered with down, is able to run about in a few hours 
after leaving the shell, and before long can fend for itself. 
The nests in which such eggs are found are roughly 
constructed, for they are not required after the hatching is 
over On the other hand, comparatively small eggs laid in 
cosily built nests usually develop into blind, naked, and 
helpless young. 
Then again, birds whose eggs are small generally lay a 
good number, and vice versa. The Wood Pigeon, for 
instance, lays from two to three, whereas the King-fisher or 
Fan-tail lays half-a-dozen or more. The explanation of this 
is simple. It would be useless for a bird to lay more eggs 
than she can cover ; if, therefore, the eggs are large, the 
number which can be covered and kept warm must 
necessarily diminish. The Kiwi has much difficulty in 
covering two eggs owing to their size. Some seabirds are 
content with a single large egg, their manner of sitting 
preventing any peer from being covered 
Colour and what it teaches. All who have collected 
eggs will notice the great variety in colour in the different 
forms. The Pigeon’s egg is white, the Duck’s light green 
