A bird in the hand

This morning I got out for my first bird ringing session of the year. We caught 46 birds, including a lot of blue tits (one pictured).

We catch the birds in a very fine net, carefully remove them (it takes years of practice), check what age and sex they are, measure and weigh them, and release them unharmed with a lightweight, uniquely numbered metal leg ring.

Weight-wise, it's the equivalent of a human wearing a watch. All the information is sent to the British Trust for Ornithology to join their enormous database.