What is "epopeus"

Epopeus (; ) was a mythical Greek king of Sicyon, with an archaic bird-name that linked him to epops (ἔποψ), the hoopoe, the "watcher". A fragment of Callimachus' Aitia ("Origins") appears to ask, "Why, at Sicyon, is it the hoopoe, and not the usual splendid ravens, that is the bird of good omen?"