This thread is a little old and i have nothing to offer OP but I would like to comment for anyone who reads this and is not sure how to go about acquiring permissions.
Almost three years ago, a friend I met through air gunning mentioned seeing a boat load of pigeons on two silos at a dairy farm near my home. Turns out I had just recently met the owners son so I asked for permission for the two of us. He invited us to speak to his father and we were welcomed with open arms. We have been pesting there ever since.
A few months ago the same buddy stopped at another farm farther away, he saw loads of pigens, They were happy to have us come remove pests whenever we want, from hosps starlings and pigeons to groundhogs, fox and crows etc.
This farm raises dairy cows but does not milk them. It is tough shooting, the silos are tall and the shots are all 72 yds or more.
So last week we were at the second permission, had had our fill and were calling it a day, and left to drive around and explore a bit.
We did not get far when we saw another farm with silos and a load of pigeons, so we stopped and asked. Sure go ahead but check in whenever you want to come back. We shot there for a while, it was another dairy farm but not optimal for two shooters.
We left there and found a larger farm with loads of pigeons on the silos, met an older gentleman on a tractor who I don't believe ever stopped smiling. His sons run the farm but he was sure they would not mind so we got right to it. He said he would give us a test run, by the time we left he told us we could come back any time.
This was last Sunday, we did not run into a problem on our quests but might not be the best day of the week to knock on doors asking to hunt. Our first permission is a mennonite family and we are asked not to hunt there on Sundays which of course we do not question.
Our story when we introduced ourselves was that we were just shooting pests on another local farm...
We already smelled like the previous farm(s) which may or may not have been a benefit, I'm going with- it did help us.
We have not yet been turned away, we show up, start a friendly, honest and respectful introductory conversation getting to the point quickly.
What we found by the end of last Sunday was that the reward for us was not the pests we were able to shoot, but was the the fact that in todays world, being the way it sometimes is, two total strangers are able to show up on a farm, with guns in the truck ready to go if allowed, strike up a conversation and then given free reign to shoot pests at will on their property.
No babysitting, and when you run into the folks later they are somewhat excited to see the pile of pests you have removed quietly and safely.
Apologies that this got so long.