If you've never made one, a bird nest helper is simply a bunch of string, hair, yarn, grass, and other materials that birds might use to build their nest. We found this fun and simple bird nest helper by Etsy seller maddyandme. Or do as we're doing and make something yourself using a mesh bag or something similar.
There are helpful tips that you should read before making a bird nest helper. Safety tips such as avoiding string longer than 3-4 inches and not offering plastic or nylon are important. You can read more about safety tips here.