(species Corvus monedula), crowlike black bird with gray nape and pearly eyes of the family Corvidae (q.v.; order Passeriformes). Jackdaws, which are 33 cm (13 inches) long, breed in colonies in tree holes, cliffs, and tall buildings: their flocks fly in formation around the site. They lay four to six light, greenish blue eggs that are spotted and blotched. The bird's cry sounds like its name: “chak.” The species ranges from the British Isles to central Asia; eastward it is replaced by the white-breasted, white-collared Daurian jackdaw (C. dauuricus).