Darwin, speaking of domesticated birds, says ('The Descent of Man,' p. 415) "these are often pampered by high feeding, and sometimes have their instincts vitiated to an extreme degree. Of this latter fact I could give sufficient proofs with Pigeons, and especially with Fowls, but they cannot be here related."
Possibly he may refer, amongst others, to such instances as the foregoing; but, if we can thus account for them in the case of Pigeons, what are we to say in regard to a pair of Great Crested Grebes, living a natural life upon a sheet of water as large perhaps as some of the smaller broads or meres? If we say it is vitiated or perverted instinct, still there must be a natural cause for what we regard as the perversion. As is well known, hermaphroditism preceded, in the march of life, the separation of the sexes, and all of the higher vertebrate animals, including man, retain in their organisms the traces of this early state. If the structure has been partly retained, it does not seem unlikely that the feelings connected with it have, through a long succession of generations, been retained also, and that, though more or less latent, they are still more or less liable to become occasionally active. This view would not only explain such actions as I have here recorded, but many others scattered throughout the whole animal kingdom, and might even help to guide us in the wide domain of human ethics.
May 24th.—Same place at 6.15 a.m. The birds are floating together again, like pork-pies on the water, but up till now (7.15) they have not approached the nest. I have then to leave.
May 25th.—Between 3 and 3.50 p.m. the birds are not at the nest, but swimming about near the opposite bank, and I think I notice in them some disposition to build another nest. The male, having swum to some distance from the bank, returns very fast to it with the other Grebe. All at once he dives, and, coming up near the bank, makes a sudden dart, and spears forward with his beak, to the confusion and flight of a Moor-hen. It is now, therefore, evident that one way, at least, of fighting adopted by these birds, is to dive, and either attack under water or just after rising—I say one because, on the first occasion, when I saw the male attack a Moor-hen near the first nest, he did not dive. I now think it probable that the first Moor-hen was attacked because he was near the platform of the male Grebe
