Improved bird ring which consists of an element (2) which can be provided with two free ends (8,10) round the birds leg and which is provided with a lock on the above-mentioned far ends (8,10), characterised in that the above-mentioned lock (6) is provided with locking agents (13) which, when the bird ring (1) is closed, prevent the far ends (8,10) of the element (2) from mutually shifting in the longitudinal direction of the bird ring (1).