Assuredly birds have a language which they alone comprehend. When danger threatens them, a particular cry is uttered by one, and immediately all of the same species hide themselves until their fears are dispelled and confidence restored. When the presence of a bird of prey is announced by the plaintive cry of the Thrush, all the feathered race of the neighbourhood are hushed into silence. Birds of prey with carnivorous instincts live in the most solitary places. The Eagle lives alone with his mate in some unapproachable aerie, his nest placed on the side of some steeply-scarped mountain, or perhaps hidden in the depth of some inaccessible ravine, whence they sally forth to visit some distant region in search of prey. It is very difficult for us to appreciate the degree of intelligence exhibited by birds. In the Mammifers, whose organisation approaches nearer to that of man, we are enabled partially to comprehend their joys and griefs; but in the case of birds we are reduced to conjecture in order to arrive at an estimate of their sensations. To explain this profound mystery a word has been invented which satisfies easy minds: we call the sentiment which leads birds to perform many admirable actions which are related of them, _instinct_. The tenderness of the mother for her young--a tenderness so full of delicacy and foresight--is, we say, only the result of _instinct_. It is agreed on all hands, however, that this instinct singularly resembles the intelligence called reason, and, in the opinion of many, is nothing else. Reproduction in birds occurs at intervals regulated by nature, and they are distinguished, above all other creatures, for the fidelity of their affections. It is frequently a matter of observation that a male attaches itself to a female, and they henceforth live together till the death of one or both; and many affecting scenes are described where death has overtaken one of the affectionate pair. When the breeding season approaches, the habits of the female are modified; she abandons her former freedom, and, having laid her eggs, she passes her whole time in incubation, defying hunger and all other dangers, apparently well instructed in the fact that the equal and prolonged heat communicated by their contact with her body is necessary to hatch them. During the period of incubation the male, in most instances, watches the female, and supplies her with food; afterwards the little ones are waited on by both the parent birds with the tenderest care until they finally attain the use of their wings. The solicitude of birds for their young is first manifested in the choice of the locality for the nest, and in the care with which this cradle of their progeny is constructed. But all this disappears when the young no longer require the maternal protection. [Illustration: Fig. 72.] [Illustration: Fig. 73.] [Illustration: Fig. 74.] [Illustration: Fig. 75.]