It is common all over the pampas, ranging as far south as the Rio Colorado in Patagonia. In the breeding season it congregates in pools, and one is then struck by their extraordinary vocal powers, which they exercise by night. The performance in no way resembles the series of percussive sounds uttered by most batrachians. The notes it utters are long, as of a wind instrument, not unmelodious, and so powerful as to make themselves heard distinctly a mile off on still evenings. After the amorous period these toads retire to moist places and sit inactive, buried just deep enough to leave the broad green back on a level with the surface, and it is then very difficult to detect them. In this position they wait for their prey--frogs, toads, birds, and small mammals. Often they capture and attempt to swallow things too large for them, a mistake often made by snakes. In very wet springs they sometimes come about houses and lie in wait for chickens and ducklings. In disposition they are most truculent, savagely biting at anything that comes near them; and when they bite they hang on with the tenacity of a bulldog, poisoning the blood with their glandular secretions. When teased, the creature swells itself out to such an extent one almost expects to see him burst; he follows his tormentors about with slow awkward leaps, his vast mouth wide open, and uttering an incessant harsh croaking sound. A gaucho I knew was once bitten by one. He sat down on the grass, and, dropping his hand at his side, had it seized, and only freed himself by using his hunting knife to force the creature's mouth open. He washed and bandaged the wound, and no bad result followed; but when the toad cannot be shaken off, then the result is different. One summer two horses were found dead on the plain near my home. One, while lying down, had been seized by a fold in the skin near the belly; the other had been grasped by the nose while cropping grass. In both instances the vicious toad was found dead, with jaws tightly closed, still hanging to the dead horse. Perhaps they are sometimes incapable of letting go at will, and like honey bees, destroy themselves in these savage attacks. CHAPTER V. FEAR IN BIRDS. The statement that birds instinctively fear man is frequently met with in zoological works written since the _Origin of Species_ appeared; but almost the only reason--absolutely the only plausible reason, all the rest being mere supposition--given in support of such a notion is that birds in desert islands show at first no fear of man, but afterwards, finding him a dangerous neighbour, they become wild; and their young also grow up wild. It is thus assumed that the habit acquired by the former has become hereditary in the latter--or, at all events, that in time it becomes hereditary. Instincts, which are few in number in any species, and practically endure for ever, are not, presumably, acquired with such extraordinary facility.