Sources : Anthus

Aristotle [ca. 350 BCE] (De animalibus Book 9, chapter 1.7): The anthus is the enemy of the horse, for it drives the horse from its pasture, for the anthus also feeds on grass; it is dim-sighted and not quick; it imitates the voice of the horse, which it frightens by flying at it, and drives it from its pasture; if the horse can seize upon it, he will kill it. The anthus lives near rivers and marshes; it is of a fine color, and lives well. - [Cresswell translation, 1887]

Pliny the Elder [1st century CE] (Natural History, Book 10, 83.95): ...the thistle-finch, the smallest of birds, [lays] twelve [eggs] at a time. - [Rackham translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.12, 5.64): [Thomas erroneously thought the bird described here was a type of finch, and so transcribed the name anthus as achantis. This led him to misquote Pliny. Thomas describes the bird under two names, achantis and iboz.] [Birds 5.12] Achantis is a bird, as Pliny says. This bird is eats grass for food, and is therefore hated by horse. When the bird sees the grazer [horse] come upon it and snatch the grass, it flees and takes what vengeance it can by mocking the horse's neighing, imitating the horses' own voice as it neighed. Although this bird is small in body, it is fertile, for it produces a dozen chicks at once. [Birds 5.64] Iboz is a bird of the East. It is a very courageous and strong bird. There is a perpetual hatred between the bird and the race of horses, and this is the reason: ybos is a bird that feeds on grass, like a goose. But it has a terrible voice, which in a certain way imitates the voice of a horse; but this is very difficult to hear. But the horse hates the bird, because it is frightened by its voice. Yboz hates the horse, because the horse drives the bird out of the pasture. When the bird yboz grazes on the grass, the horse, driven by envy and jealousy, drives it away. The yboz, however, when it sees the horse standing safely in the pasture, utters a terrible voice and frightens the horse and forces it to flee, and thus sometimes killing the fledgling out of excessive restlessness. - [Badke translation/paraphrase]