Sound-supressed AR15 in 300 Blackout, with an infrared night-vision scope.
I doubt the guy is made of money.
Anything will do. I'm sure a shotgun would be great, but a semi auto rifle with a large magazine is ideal. If you have any friends with an M1A or AR10, you could knock down more than one in a line with .308. And .308 hits like a damn freight train compared to .223. Shoot the largest ones first and wait for the babies to return to their dead mom. Then take them out as well.
Oh, and film that shite.