How did you find your permissions?

If I may add a couple follow up questions:

- What do you do with all the dead animals?

- Anyone get paid for their "Permission"?
If you can get permission to pest on somebody else’s land I would suggest not tempting termination of your privileges by being rude enough to try to profit from it.
They know you are doing it because you enjoy it and not out of some odd sense of civic duty.

I pick up and remove from the property every bird I can.
 
You guys lucky. Around my town when I moved in 20 years ago ppl told me they don't have bbq's but horses in backyards :)
During years I learned all these commercial horse farms and grass feed/hay production.
I visited one farm years back and the owner changed he's mind "what if the animals get lead poisoning?"
Right after that I joined my gunclub and I am the only one there with airguns only.