Willistown Conservation Trust in Pennsylvania carries out bird banding to help researchers understand bird populations. Led by licensed bird banders, a team of volunteers catches birds using mist nets — 8-foot tall nets made of fine nylon string that practically disappear when strung out between poles. After carefully untangling birds from the net, volunteers weigh and measure the birds, affixing a small metal band to their legs with a unique ID. Compiling records for many banded birds helps keep track of whole species. More info and transcript at BirdNote.org. Want more BirdNote? Subscribe to our weekly newsletter. Sign up for BirdNote+ to get ad-free listening and other perks. BirdNote is a nonprofit. Your tax-deductible gift makes these shows possible.