Alfred Newton and Hans Friedrich Gadow

“ In marked contrast to such artless care stand the wonderful structures which others, such as the tailor-bird, the bottle-titmouse or the fantail-warbler, build for the comfort or safety of their young. ”

“ The magpie, as though self-conscious that its own thieving habits may be imitated by its neighbours, surrounds its nest with a hedge of thorns. Very many birds of almost every group bore holes in some sandy cliff, and at the end of their tunnel deposit their eggs with or without bedding. ”

“ Certain it is that some birds whether by mistake or stupidity do not infrequently lay their eggs in the nests of others. It is within the knowledge of many that pheasants' eggs and partridges' eggs are often laid in the same nest, and gulls' eggs have been found in the nests of eider-ducks and vice versa; a redstart and a pied flycatcher will lay their eggs in the same convenient hole the forest being rather deficient in such accommodation; an owl and a duck will resort to the same nest-box, set up by a scheming woodsman for his own advantage ”

“ The apteryx seems to entrust its abnormally big egg to an excavation among the roots of a tree-fern; while a band of female ostriches scrape holes in the desert-sand and therein promiscuously drop their eggs and leave the task of incubation to the male. Some megapodes bury their eggs in sand, leaving them to come to maturity by the mere warmth of the ground, while others raise a huge hotbed of dead leaves wherein they deposit theirs, and the young are hatched without further care on the part of either parent. ”

“ The golden eagle, too, remarkably adapts itself to circumstances, now rearing its young on a precipitous ledge, now on the arm of an ancient monarch of the forest and again on a treeless plain, making a humble home amid grass and herbage. ”

“ But though in a general way the dictates of hereditary instinct are rigidly observed by birds, in many species a remarkable degree of elasticity is exhibited, or the rule of habit is rudely broken. Thus the falcon, whose ordinary eyry is on the beetling cliff, will for the convenience of procuring prey condescend to lay its eggs on the ground in a marsh, or appropriate the nest of some other bird in a tree. ”

“ The egg of the parasite is introduced into the nest of the dupe, and after the necessary incubation by the fond fool of a foster-mother the interloper successfully counterfeits the heirs, who perish miserably, victims of his superior strength. ”

“ The instinct of finding food for the family is predominant, and where most food is there will the feeders be gathered together. This explains, in all likelihood, the associated bands of ospreys or fish-hawks, which in North America breed (or used to breed) in large companies where sustenance is plentiful, though in the Old World the same species brooks not the society of aught but its mate. ”

“ Speaking broadly, the largest birds lay the largest eggs and require the longest time for incubation, but there are very many exceptions, and only birds of the same group can be compared with each other. ”

“ Birds in which the plumage of both sexes is showy or brilliant in colour, and which nidificate in open nests. This group forms one of those exceptions which at first sight appear seriously to affect the validity of Wallace's theory. In most of the cases, however, the birds, as, for instance, crows, gulls, herons, are either well able to defend themselves and their nests or, as, for instance, the sandpipers, they seek safety for themselves in flight, relying upon the protective tints of their eggs or young. ”

“ The condition of the newly hatched birds also varies extremely. The Nidifugae are born with their eyes open, are thinly clothed with neossoptiles of simple structure, leave the nest on the first day and feed themselves. The Nidicolae are born blind, remain a long time in the nest and have to be fed by their parents. ”

“ The eggs of owls are always white, whether they be deposited in holes on the bare ground or in open nests in a tree. The eggs of the goshawk are white, but those of its small relation, the sparrowhawk, are always blotched, the nest of both being built precisely in the same kind of position, &c. ”

“ In all such cases it is not possible to say which species is so constituted as to obtain the mastery, but it is not difficult to conceive that in the course of ages that which was driven from its home might thrive through the fostering of its young by the invader, and thus the abandonment of domestic habits and duties might become a direct gain to the evicted householder. ”

“ Some of the grebes and rails seem to avail themselves in a less degree of the heat generated by vegetable decay and, dragging from the bottom or sides of the waters they frequent fragments of aquatic plants, form of them a rude half-floating mass which is piled on some growing water-weed—but these birds do not spurn the duties of maternity. ”

“ In regard to the almost countless cases of spotted eggs in holes or covered nests, of which so many groups of birds furnish examples either wholly or in part, it has been suggested that the species in question has taken to hiding its eggs in times comparatively recent, and has not yet got rid of the ancestral habit of secreting and despositing pigment. ”