Ducks in a tree? Yes.
Wood Ducks are quite at home in the trees as you can see in these photos of a female (top) and male.
Wood Ducks nest in tree holes, usually in those caused by a lost tree limb. But they will also use an old Woodpecker nest. The male is watching as the female examines this potential home for her ducklings.
She makes a very careful examination.
Birds in My Viewfinder 