although much more frequent in the unions of birds than in those of human beings, are not, however, the unfailing rule. With birds, as with men, there seems to be a good number of irregular cases—individuals of imperfect moral development and of fickle disposition. This may be inferred from the facility with which, among certain species of monogamous birds, the dead partner is replaced. Jenner, who introduced vaccination, relates that in Wiltshire he has seen one of a couple of magpies killed seven days in succession, and seven times over immediately replaced. Analogous facts have been observed of jays, falcons, and starlings. Now, when it concerns animals that are paired, each substitution must correspond to a desertion, the more so as the observations were made in the same locality and in the height of the breeding season.[1]
Very peculiar fancies sometimes arise in the brains of certain birds. Thus we see birds of distinct species pairing, and this even in a wild state. These illegitimate unions have been observed between geese and barnacle geese, and between black grouse and pheasants.
Darwin relates a case of this kind of passion suddenly appearing in a wild duck. The fact is related by Mr. Hewitt as follows:—"After breeding a couple of seasons with her own mallard, she at once shook him off on my placing a male pintail in the water. It was evidently a case of love at first sight, for she swam about the new-comer caressingly, though he appeared evidently alarmed and averse to her overtures of affection. From that hour she forgot her old partner. Winter passed by, and the next spring the pintail seemed to have become a convert to her blandishments, for they nested and produced seven or eight young ones."[2] It is difficult not to attribute such deviations as these to motives similar to those by which we are ourselves actuated—to passion, caprice, or depravity. They certainly cannot be accounted for by the theory of mechanical and immutable instinct. Such facts clearly prove that animal psychology, although less complicated than our own, does not differ essentially from it, and consequently throws much light on our present investigation. The adventure of the wild duck, for example, may, without any alteration, be read as a
