Hang the bag of nesting materials in a location that is visible to birds, such as near their bird feeder or bird bath. Also make sure that the birds have plenty of places to perch and browse, either on the bag itself or on tree branches or railings right next to the bag.
Then, all you have to do is keep your eye out so that you can enjoy watching the birds make use of your materials. If you solve a scientific mystery for yourself in the process, then all the better!
This is all great stuff. I think the mesh bags are fine to use. We use them in the UK for lots of different bird foods and never had a problem with birds getting trapped before. Plus recycling these mesh bags is a good idea (we cant recycle here).
thank you for the ideas and inspiration!