What are indicators that a crow is very old?
Establishing the age is very difficult, or impossible, if the bird is older than 3 years. Up to then three types of age can be recognised. Juvenile with fresh plumage, duller black feathers and the inside of upper mandible being pink. 1st year autumn and 2nd year spring with moult limit between moulted glossy body feathers and lesser coverts and duller juvenile feathers on wing and tail. These birds also show worn flight and tail feathers and the inside of the upper mandible has got still pink areas. Lastly there are the adult birds with glossy black plumage on wing and tail, without moult limit and the inside of the upper mandible is dark, almost black.
Other than that it becomes guess work, as for example arthritic changes to leg joints can be caused by old age, but they can be also caused by disease or could be even inherited. Scarring, wear and tear or even damage to the beak aren’t reliable indicators either. A cataract affecting both eyes could be an indication of old age though. A cataract affecting one eye only is more indicative of a trauma or infection.
Generally speaking, with increasing age, the plumage becomes slightly duller and lighter, and some birds seem to develop an increasing number of white facial feathers around their eyes.