678 BIRDS. 
of their parental care. Other creatures, indeed, such as sticklebacks 
among Fishes, and squirrels among Mammals, besides numerous Insects, 
build nests, but the habit is most perfectly developed among Birds. 
As is well known, each species has its own peculiar style of nest, and 
builds it of special materials, Generally the nest is solitary, hidden in 
some private nook. The perfection of art which is reached by some 
birds in the making of their nests is marvellous ; they use their bills and 
their feet, and smooth the inside by twisting round and round. Usually 
the hen does most of the work, but her mate sometimes helps, both in 
building the nests and in hatching the young. 
The nest is a cradle rather than a house, for its chief use is to secure 
an approximately constant warmth for the young which are being 
formed within the eggs; and to afford protection for the helpless 
fledglings. At the same time, the nest secures the comfort of the 
parent-bird during the days and nights of brooding. 
The variety of nests may be illustrated by mentioning the burrowed 
nests of sand-martins and kingfishers, the ground-nests of game-birds 
and gulls, the mud-nests of house- martin and flamingo, the holes 
which the woodpecker fashions in the tree-stem, the platforms built by 
doves and eagles, storks and cranes, the basket-nests of most singing- 
birds, the structures delicately woven by the goldfinch, bullfinch, and 
humming-birds, the sewed nest of the tailor-bird, the mossy nests of 
the wrens, the edible nest of the Col/ocalia, which is chiefly composed 
of mucin secreted by the salivary glands. 
Eggs of birds.—When the nest is finished, the eggs are ready to 
be laid. After they are laid, the patience of brooding begins. With 
the great care that Birds take of their young we may associate the 
comparatively small number of the eggs; but there are probably other 
reasons why the number of offspring decreases as animals become more 
highly evolved. 
The size of the egg usually bears some relation to the size of the bird. 
Of European birds, the swans have the largest eggs, the golden-crested 
wrens the smallest. It is said that the egg of the extinct J/oa some- 
times measured 9 in. in breadth and 12 in. in length; while that 
of the extinct 4pyornds held over two gallons, some six times as 
much as_an ostrich’s egg, or a hundred and fifly times as much as 
afowl’s. Yet the size of the egg is only generally proportional to that 
of the bird ; for, while the cuckoo is much larger than the lark, the eggs 
of the two are about the same size; and while the guillemot and the 
raven are almost of equal size, the eggs of the former are in volume 
about ten times larger than those of the latter. The eggs of birds 
whose young are rapidly hatched and soon leave the nests are large. 
Professor Newton remarks that ‘‘the number of eggs to be covered at 
one time seems also to have some relation to their size,” while from 
what one notices in the poultry-yard, and from a comparison of the 
habits of different birds, it seems probable that a highly nutritive, 
sluggish bird will have larger eggs than a bird of more active habit and 
sparser diet. 
The shell of the egg is often very beautifully coloured ; there is a 
predominant tint upon which are spots, streaks, and blotches of varied 
colour and disposition, so that the egg is almost always characteristic of 
