2. The hawk also builds in precipitous places; and although it is carnivorous, it does not devour the heart of the bird it has killed. Some have observed this with respect to the quail and thrush, and others with other birds. There is also a change in their mode of hunting their prey, for they do not seize them in the same way in summer and in winter. It is said that no one has ever seen the young or the nest of the carrion vulture. Wherefore Herodorus, the father of Brison the sophist, says that they come from some distant elevated land, using this proof, that many of them appear suddenly, but where they come from is not intelligible to any one. The reason is this, they make their nest in inaccessible rocks, and the bird is not an inhabitant of many countries. It produces one egg or two at the most. 3. Some birds dwell in mountains and in woods, as the hoopoe and brenthus. This bird has a good habit of life and a good voice. The trochilus dwells in thickets and holes. It is taken with difficulty, for it is swift in flight, and its disposition is weak; but its mode of life is good, and it is artful. It is also called presbys and basileus. Wherefore also they say that it fights with the eagle. CHAPTER XIII. 1. There are some which live near the sea, as the cinclus. In disposition this bird is cunning and difficult of capture, and when taken easily tamed. It appears to be lame, for its hinder parts are weak. All birds with webbed feet live near the sea, or near rivers and ponds, for their nature teaches them to seek what is advantageous for them. Many of those with divided feet live near waters and marshes, as the anthus in the neighbourhood of rivers. Its colour is beautiful, and its mode of life good. The diver lives near the sea, and when it plunges into the sea it remains as long a time as it would take a man to walk over a plethrum of ground. This bird is less than a hawk. 2. The swan also is web-footed, and lives in ponds and marshes. Its manner of life and disposition is good, and so is its mode of rearing their young and its old age. If an eagle attacks the swan, it defends itself and comes off victorious, but will not commence the fight. Swans have the power of song, especially when near the end of their life; for they then fly out to sea, and some persons, sailing near the coast of Libya, have met many of them in the sea singing a mournful song, and have afterwards seen some of them die.