Yes, they are checked very frequently. There is a ton of licensing and permitting required, so the researchers wish to steer clear of trouble. Mist nets are very regulated, as they are used for poaching as well.

They are sized for different animals, and the birds will be lured with a call into the net, where they bounce off and get caught in a pocket. They’re then retrieved and taken to a station to be measured and banded.

You can see my previous write up here, or there is this page all about mist nets.