It is a remarkable fact in the economy of nature, that of those birds
whose nests are the most liable to discovery, and whose eggs are most
exposed to observation from the form of the nests, the eggs are of that
colour which is the least different from the surrounding objects; whilst
those birds whose eggs are of a bright and positive colour, hide their
nests in the hollows of trees, or never quit them, excepting in the
night, or sit immediately that they have laid one or two eggs. It is
also to be observed that of those species which build an exposed nest,
and the females of which alone perform the duty of incubation, the
colour of the female is much less bright than that of the male, and more
in harmony with the objects by which she is surrounded during the period
in which she sits upon her eggs. It would seem, therefore, that those
birds which lay a brightly-coloured egg have the instinct to make a
close nest, or to place it in the least exposed situations; while those
which lay a sober-coloured egg are less solicitous to conceal it from
the notice of their enemies. M. Gloger, a German naturalist, has paid
great attention to this curious circumstance, and has very recently
published an elaborate memoir, in a work printed at Berlin, in which he
notices the habits of all the species of birds indigenous to Germany, in
confirmation of the theory. Our limits will not allow us to notice the
particular species which he enumerates; but it may be sufficient to
excite attention to this subject, to mention, that the birds which lay
an egg perfectly white (the most attractive of colours) make their nests
in holes of the earth, and cavities of trees, such as the kingfisher and
the woodpecker, or construct them with a very narrow opening, as the
domestic swallow; that the same coloured egg is found amongst the birds
which scarcely quit their nests in the day, as hawks and owls; and that
such birds as doves, which only lay one or two eggs, and sit immediately
after, have their eggs white. The bright blue or bright green egg
belongs to birds which make their nests in holes, as the starling, or
construct them of green moss, or place them in the midst of grass, but
always well covered. The eggs of many gallinaceous birds, that make
their nests carelessly in the grass, are of a pale and less decided
green, such as those of the partridge and pheasant. Of the
mixed-coloured eggs, those of which white forms the ground belong to
birds that make very close nests. Speckled eggs, with a dark or dirty
ground, belong to the largest number of species. Almost all the song
birds lay such eggs; and building open nests, they almost invariably
line the inside of them with materials of a harmonious colour with the
eggs, so that no evident contrast is presented which would lead to their
destruction.--_Companion to the Almanac._
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