Measuring 34–39 cm (14-15 in), the jackdaw is the smallest species in the genus Corvus. Most of the plumage is black or greyish black except for the cheeks, nape and neck, which are light grey to greyish silver. The iris of adults is greyish white or silvery white, the only member of the genus outside of the Australasian region to have this feature. The iris of juvenile jackdaws is light blue.
In flight, jackdaws are separable from other corvids by their smaller size, faster and deepers wingbeats and proportionately narrower and less fingered wings. They also have a shorter, thicker neck, a much shorter bill and frequently fly in tighter flocks. Underwing is uniformly grey, unlike choughs.
On the ground, jackdaws strut about briskly and have an upright posture.
Sexes and ages are alike.[16][10]
[edit] Voice
Jackdaws are voluble birds. The call, frequently given in flight, is a metallic and somewhat squeaky, "chyak-chyak" or "kak-kak". Perched birds often chatter together, and before settling for the night large roosting flocks make a cackling noise. Jackdaws also have a hoarse, drawn-out alarm-call.[10]
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