Sources : Linachos

Aristotle [ca. 350 BCE] (De animalibus, Book 9, 33): The eagle appears to eject its young from the nest from envy; for it is an envious and hungry bird, and not quick in seizing its prey. It captures large creatures when it can. When its young have grown, it envies them, for they have good food, and tears them with its claws. ... The sea-eagle is very quick-sighted, and compels its young to gaze on the sun before they are feathered. If anyone of them refuse, it is beaten and turned round, and the one of them which first weeps when gazing on the sun is killed, the other is reared. It lives near the sea side, and obtains its food by pursuing marine birds, as it was before remarked. It pursues and takes them one at a time, watching them as they emerge from the sea. And if the bird, as it rises, sees the eagle watching it, it dives again from fear, in order that it may rise again in another place: but the eagle's quick sight enables him to pursue the bird till it is either suffocated, or taken on the wing; but it never attacks them in any numbers, for they drive it away by sprinkling it with their wings. - [Cresswell translation, 1887]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.77): Linachus is a bird, as Aristotle says, of very sharp sight, and it forces his children to look at the Sun before they are fully fledged; and for this reason he strikes them and turns them to the orb of the Sun; and if any chick's eye waters, it kills that one and feeds the others [also said of the eagle]. This bird lives near the sea and feeds on the birds that are in the sea. Sometimes the flying bird is seen above by the birds swimming in the sea, and they drown themselves in terror. The linachus descends near the waters and forces the birds to such a sudden drowning, that it suffocates them in the water. Then, suffocating in the water, the birds are brought to the surface by the force of the water, and these it snatches and carries to land. - [Badke translation/paraphrase]