Bird ringing or banding is a practice which is used to study populations of wild birds, and to identify tamed or domestic birds. When a bird is ringed, a small metal or plastic ring is attached to the wing or feet of the bird, and then the bird is released. The ring has individual markings which can be used in the future to identify that particular bird, along with contact information for the person or organization who ringed the bird in the first place. And yes, the correct terminology is “ringed,” rather than “rung,” although it sounds awkward; in regions where people refer to bird banding, the ring is known as a band, and the bird is said to be banded.
Various forms of bird ringing have been practiced since at least the second century BCE, when the Greeks and Egyptians identified birds with colored threads tied to their legs. The Greeks used these birds as messengers, attaching messages to the cords, and these identifying markings were also used to track birds kept for falconry. In the 1800s, bird ringing for the purpose of studying bird populations emerged.
The process of bird ringing starts with catching the bird, using a variety of techniques ranging from mist netting to trapping young birds in the nest. The ring is attached to the bird, and the markings on the ring are noted down along with information about the bird, such as its estimated age, measured weight, and the location where it was found. Then, the bird is released; when sightings of the ring are reported in the future, scientists can use the information from the sightings to track the bird.
When information about a bird wearing a ring is retrieved, this is known as “ring recovery.” In some regions, scientists actually specifically trap birds for the purpose of studying their rings, and others design field-readable rings, so that the data can be collected without disturbing the bird. Using bird ringing, researchers can track bird populations and observe their lifestyles, hopefully learning more about them in the process.
Bird ringing is not harmful to the bird. The rings are very lightweight, and could be compared to a set of keys in the pocket of a human. When the ring is applied, the researcher is careful to be extremely gentle, and to monitor the bird for a few hours after release to make sure it is healthy and undisturbed.
If you find a dead bird with a ring, report it to the agency listed on the ring; if you cannot see a number to report the number to, contact your local department of wildlife for information about the best person or group to talk to about the bird ring. Never try to capture a bird which has been ringed, but feel free to sight the ring with binoculars and call in a sighting; researchers are always happy to hear from people in the field about the movements of their birds.