The eagle which we have mentioned as forming the third species, pursues the aquatic birds in the vicinity of standing waters: in order to make their escape they plunge into the water every now and then, until at length they are overtaken by lassitude and sleep, upon which the eagle immediately seizes them. The contest that takes place is really a sight worthy to be seen. The bird makes for the shore to seek a refuge, especially if there should happen to be a bed of reeds there; while in the mean time the eagle endeavors to drive it away with repeated blows of its wings, and tumbles into the water in its attempts to seize it. While it is standing on the shore its shadow is seen by the bird, which immediately dives beneath, and then making its way in an opposite direction, emerges at some point at which it thinks it is the least likely to be looked for. This is the reason why these birds swim in flocks, for when in large numbers they are in no danger from the enemy; as by dashing up the spray with their wings they blind him. Again, it often happens that the eagle is not able to carry the bird aloft on account of its weight, and in consequence they both of them sink together. This and the haliætus beat their young ones while in an unfledged state, with their wings, and force them from time to time to look steadily upon the rays of the sun; and if the parent sees either of them wink, or even its eye water, it throws it headlong out of the nest, as being spurious and degenerate, but rears the one whose gaze remains fixed and steady. Eagles build among rocks and trees; they lay three eggs, and generally hatch but two young ones, though occasionally as many as three have been seen. Being weary of the trouble of rearing both, they drive one of them from the nest: for just at this time the providential foresight of Nature has denied them a sufficiency of food, to save the young of all other animals from becoming their prey. During this period, their talons become reversed, and their feathers grow white from continued hunger, so that it is not to be wondered at that they take a dislike to their young. The ossifrage, however, a kindred species, takes charge of the young ones thus rejected, and rears them with its own; but the parent bird still pursues them with hostility, even when grown up, and drives them away, as being its rivals in rapine. Under any circumstances, one pair of eagles requires a very considerable space of ground to forage over, in order to find sufficient sustenance; for which reason they mark out by boundaries their respective allotments. They do not immediately carry off their prey, but first deposit it on the ground, test its weight and then fly away with it.