Their eggs are white and shining; yet it is a difficult matter to discover, from beneath, whether there are eggs in the nest or not, while they are well hidden by the thick foliage above.

The Australian podargihuge goatsuckers--build very similar nests, and their white eggs are protected in the same manner.

Some large and powerful birds, as the swans, herons, pelicans, cormorants, and storks, lay white eggs in open nests; but they keep careful watch over them, and are able to drive away intruders.

On the whole, then, we see that, while white eggs are conspicuous, and therefore especially liable to attack by egg-eating animals, they are concealed from observation in many and various ways.

We may, therefore, assume that, in cases where there seems to be no such concealment, we are too ignorant of the whole of the conditions to form a correct judgment.
We now come to the large class of coloured or richly spotted eggs, and here we have a more difficult task, though many of them decidedly exhibit protective tints or markings.