Hey Loomis. You are safe between 8-12 inches in most areas. Raptors and geese like short grass heights for hunting and feeding. Too short creates a problem and too tall invites certain predators that like to dig under perimeter fencing.
I agree with JB. Damned if you do and damned if you don’t —does apply with wildlife. Keeping samplings and cattails cut in ditch-lines is always parallel to grass heights as they will always find a weak link in your attempts to deter raptors, geese etc.