For those of you who know nothing about this, I assure you it's not cruelty against birds. My mother operates a banding station where birds are harmlessly caught, given a unique number, weighed, checked for overall health, etc. Birds can then be tracked and studied around the country and in other countries as they migrate and are caught in other banding stations.
The data collected by these banding stations around the world help to determine the health of birds around the world, the impact of development and pollution, population declines and also help to impact environmental laws by finding out where endangered birds migrate and nest.

If you are interested, here is the website :[link]