What happens next?

How to keep birds out of a barn
Keep your grain in bird-proof containers.
If birds have easy access to your grain, they'll associate your barn with food and keep coming back. To prevent that from happening, store your grain in bird-proof containers so birds can't get to it.
Large garbage bins with lids and sealable plastic containers are good bird-proof options for storing your grain. Use covered feeders to feed your barn animals.