In all the instances given the sitting-bird invariably leaves the eggs uncovered when it quits them, and consequently their safety depends solely on the colours which adorn them."[81] The wonderful range of colour and marking in the eggs of the guillemot may be imputed to the inaccessible rocks on which it breeds, giving it complete protection from enemies.

Thus the pale or bluish ground colour of the eggs of its allies, the auks and puffins, has become intensified and blotched and spotted in the most marvellous variety of patterns, owing to there being no selective agency to prevent individual variation having full sway.
The common black coot (Fulica atra) has eggs which are coloured in a specially protective manner.

Dr.William Marshall writes, that it only breeds in certain localities where a large water reed (Phragmites arundinacea) abounds.

The eggs of the coot are stained and spotted with black on a yellowish-gray ground, and the dead leaves of the reed are of the same colour, and are stained black by small parasitic fungi of the Uredo family; and these leaves form the bed on which the eggs are laid.
The eggs and the leaves agree so closely in colour and markings that it is a difficult thing to distinguish the eggs at any distance.

It is to be noted that the coot never covers up its eggs, as its ally the moor-hen usually does.
The beautiful blue or greenish eggs of the hedge-sparrow, the song-thrush, and sometimes those of the blackbird, seem at first sight especially calculated to attract attention, but it is very doubtful whether they are really so conspicuous when seen at a little distance among their usual surroundings.