The Crosman/Benjamin Marauder is a very accurate pre-charged pneumatic air rifle (PCP) to at least 50 yards, well beyond with practice and good optics, and is virtually silent due to the factory shroud.
Crosman | Airguns | Rifles | PCP | Marauder Rifle (.22) It is pretty much mostly American made.
You charge it to 3000 psi with a scuba or carbon fiber tank, or do it the hard/manly way with a special hand pump. You can also use nitrogen, if you have tanks on the spread with adequate pressure (2600 is fine). For blackbird, the .22 is more wind resistant with better retained energy. You'd be using about 14.6 grain lead pellets doing about 900 fps, although there are tin-based green alternatives, if that's a concern. There are no open sights, so decent glass is a must.
I have a couple variations and recommend it highly based on personal experience, although I use it more for gophers and ground squirrels.
It would be more quiet and a lot cheaper than 12 ga. or propane, and you'd likely be a heckuva marksman after a week or so.
An alternative would be to find interested airgunners in your area, and open the field to them on a written permission basis. I could probably find some volunteers if you're so inclined. Some of them would arrive with much fancier air rifles. Air gunners are a breed apart, and you'd probably find them to be mature, sober, safe, and agreeable. Otherwise, you'd still be the one with the shotgun... :laughing: