Over-exploitation and loss of habitat is blamed. In around the 19-teens a pair of beaver were released to the wild and there were a few more pairs reintroduced. Probably no more than a half dozen in all. The most significant natural predator on beaver is the wolf, and we don't have any wolves in Connecticut. Some young beaver may fall to bobcats, coyotes and perhaps even foxes, but that's it.
Raptors are of no significant influence.
So if you want to mitigate the damage done by nuisance beavers, you'd better find a local trapper and buy him a cup of coffee. He has short ears, webbed feet, a rich brown fur that acts like a wet suit, and a unique, paddle-shaped, scaled, hairless tail. The multi-purpose tail is slapped on the water to warn other beavers. It's a prop when he stands and a rudder when he swims. Thin membranes protect the beaver's eyes when underwater.