how is bird ringing done?

Leg ring

A bird is ringed with a lightweight strip of aluminium, wrapped loosely around one of its legs. The band weighs less than a half-percent of the bird's body weight.

Normal life

Even with a ring on its leg, the bird is able to move normally. This is important for both ethical and scientific reasons; ringing birds would not yield any meaningful results if it interfered with their normal function.