* * *

How wonderful it is that this parental instinct, so beautiful in itsperfect simulation of the action of the bird that has lost the power offlight, should be found in so large a number of species! But when wefind that it is not universal; that in two closely-allied species onewill possess it and the other not; and that it is common in suchwidely-separated orders as gallinaceous and passerine birds, in pigeons,ducks, and waders, it becomes plain that it is not assignable tocommunity of descent, but has originated independently all over theglobe, in a vast number of species. Something of the beginnings andprogressive development of this instinct may be learnt, I think, bynoticing the behaviour of various passerine birds in the presence ofdanger, to their nests and young. Their actions and cries show that theyare greatly agitated, and in a majority of species the parent bird flitsand flutters round the intruder, uttering sounds of distress. Frequentlythe bird exhibits its agitation, not only by these cries and restlessmotions, but by the drooping of the wings and tail--the action observedin a bird when hurt or sick, or oppressed with heat. These languishingsigns are common to a great many species after the young have beenhatched; the period when the parental solicitude is most intense. Inseveral species which I have observed in South America, the languishingis more marked. There are no sorrowful cries and restless movements; thebird sits with hanging wings and tail, gasping for breath with open bill--in appearance a greatly suffering bird. In some cases of thisdescription, the bird, if it moves at all, hops or flutters from ahigher to a lower branch, and, as if sick or wounded, seems about tosink to the ground. In still others, the bird actually does drop to theground, then, feebly flapping its wings, rises again with great effort.From this last form it is but a step to the more highly developedcomplex instinct of the bird that sinks to the earth and flutterspainfully away, gasping, and seemingly incapable of flight.