Bald eagles are definite predators of ducks. They can carry them right in the air with no problem and will toss small ducks around to each other. They can be a threat to geese as well, but less likely. I think I read that 40% of their diet, on average, are ducks and coots. The rest of their diet is composed of fish and other birds/animals. I would definitely be concerned for your ducks if they stick around.
The geese at our lake, even the domestic ones, almost always alert to birds of prey even if it's just a small hawk. They totally ignore vultures.
Edited by desertdarlene - 3/17/12 at 8:28am