By ringing birds, scientists first discovered where they went. Modern technology, such as satellite tracking and DNA testing, has brought us even more detailed information. Ringing is only carried out by qualified people so that the birds are not harmed or distressed. First, bird ringers catch the bird at a special trapping place, or at the nest when the bird is still a fledgling.
The Stainless Steel ring is fitted, details of the species, its age and its condition and the location it is being ringed in are noted and then the bird is released as soon as possible. Bird rings are designed by the BTO (British Trust for Ornithology), and are often made of lightweight Stainless Steel that does not harm the bird. They come in different sizes to fit different species.
A unique number on each ring shows where and when the bird was caught, and a return address shows where to send information. If the bird is caught or seen somewhere else, this number tells scientists where it has come from. Only specially trained ornithologists (bird scientists), called ringers, have a licence to do the ringing. The coloured rings on cage birds and racing pigeons are for identifying their owners, and have nothing to do with studying migration.
Catch the birdie
Ringers usually work at bird observatories and other special ringing sites. These are often on islands or headlands where lots of migrants pass through. They use nets with a very fine mesh, called mist nets, which they set up between bushes to catch birds flying past.
Another kind of trap, called the Heligoland trap, directs birds down a narrowing tunnel of nets until they are caught at the end. Large nets are sometimes fired with rockets to catch larger birds, such as geese, as they feed on the ground.
Handling, ringing and releasing birds is a tricky job. Ringers need skill and experience to make sure that birds are not harmed or distressed. First they untangle the bird very carefully. Then they identify it and fit the ring. Finally, before releasing it, they make measurements and record information about its size, weight and age.
Source: RSBP - bird ringing