Where are you seeing plenty of squirrels, rabbits and wildfowl? Turkeys, yes. They are tough customers and do a good job of defending their young. Not much will take out a turkey head to head. Plus they roost in trees, above the fray. Small predators avian or other aren't much of a threat to a turkey. Crows are opportunists and scavengers mostly.
Many studies have been done, money spent and spent, and again. Nice work if you can get it! There seems to be some intangibles that just can't be pinned down or there would be an answer. SO even if you cannot "draw a conclusion" from practical experience you can at least add it to the collective knowledge base and accept that even the unwashed have eyes.
