Ovid [1st century CE] (The Metamorphoses, Book 13, 576-622): But Aurora had no time for being moved by the fall and ruin of Hecuba and Troy, though she had aided its defense. A closer sorrow, and a private grief tormented her, the loss of her son Memnon, whom she, his bright mother, had seen wasted by Achilles’s spear on the Phrygian plain. She saw it, and that color, that reddens the dawn, paled, and the sky was covered with cloud. His mother could not bear to look at his body laid on the summit of the funeral pyre, but with disheveled hair, just as she was, she did not scorn to fall at the feet of mighty Jove, adding tears to these words: I come bereft of my Memnon, who bore arms bravely, but in vain, for his uncle Priam, and in his youth has fallen to mighty Achilles (so you willed). I beg you to grant him some honor, as a solace for his death, great king of the gods, and lessen a mother’s wound!’ Jupiter nodded, while Memnon’s steep pyre collapsed in leaping flames, and the daylight was stained with columns of black smoke, like the river-fog the naiad breathes out, that does not admit the light beneath it. Dark ashes flew upwards, and gathering into a ball and solidifying, they formed a shape, and it drew life and heat from the fire (its own lightness giving it wings). At first resembling a bird, then a true bird, it clapped its wings, and innumerable sisters, sprung from the same natal source, sounded too. Three times they circled the pyre, and three times their clamor rose in the air in consonance, on the fourth flight the flock divided. Then in two separate fierce bands they made war, wielding beaks and hooked talons in rage, wearying wing and breast in the struggle. Remembering they were sprung from a brave hero, they fell as offerings to the buried ashes of their kinsman’s body. The source of these suddenly created birds gave them his name: from him they were called the Memnonides: and when the sun has transited his twelve signs, they war and die again in ritual festival. - [Kline translation]

Pliny the Elder [1st century CE] (Natural History, Book 10, 37): Some authorities state that every year birds fly from Ethiopia to Troy and have a fight at Memnon's tomb, and consequently they call them Memnon's daughters. Cremutius records having discovered that every four years they do the same things in Ethiopia round the royal palace of Memnon. - [Rackham translation]

Isidore of Seville [7th century CE] (Etymologies, Book 12, 7:30): Memnonides are Egyptian birds named after the place where Memnon perished. They are said to fly in flocks from Egypt to Troy near the tomb of Memnon, and hence the Trojans call them memnonia. They come to Troy every fifth year, and after they have flown around for two days, on the third day they enter into a battle with each other, lacerating themselves with talons and beaks. - [Barney, Lewis, et. al. translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.83): The memnonides birds are from Egypt, from the place where Memnon perished, as Isidore and Pliny say. For they are said to fly in groups from Egypt to Ilium near the tomb of Memnon, and for this reason the people of Ilium are called Memnonids. In the fifth year they come to Ilium, and after flying around the tomb two days, on the third day they enter into battle and tear themselves apart with claws and beaks. - [Badke translation/paraphrase]