Sources : Chloreus

Aristotle [ca. 350 BCE] (De animalibus Book 9, chapter 2.3): Among birds the poecilis and the lark and the wood-pecker and chloreus are enemies, for they eat each others' eggs. - [Cresswell translation, 1887]

Pliny the Elder [1st century CE] (Natural History, Book 8, 95.203): [There are quarrels] between the raven and the chloreus when searching for one another's eggs by night - [Rackham translation]

Thomas of Cantimpré [circa 1200-1272 CE] (Liber de natura rerum, Birds 5.29): Choretes is a bird, according to Pliny. This bird has a lifelong enmity with the raven. But the raven does not always cease to be his adversary, given his turn. In these hatreds, therefore, they do not cease to devise plots for each other; when, therefore, the dark night has given all the animals an opportunity of repose by its silence, they do not even then cease to injure one another, but, coming out of their nests, alternately searching for their eggs more eagerly, if they find them, they snatch them away. They do the same to their own chicks, and in many other ways, by which cruel birds infest themselves. - [Badke translation/paraphrase]

Albertus Magnus [1st century CE] (De animalibus, Book 23, 25): Choreles are birds that fight with ravens without fail. At night, however, they cease to fight, but at all other times they fight, and snatch each other's young. - [Catholic Library]