On the east side of 154th Ave NE just south of Redmond Way
(immediately adjacent to the Sammamish Slough) I have noticed a tree
with what look like waterfowl -- ducks perhaps? -- sitting in the
branches of the tree -- as many as 20 or 30 at a time.

This seems odd - I am not aware of waterfowl nesting in trees (besides
the wood duck).

I wonder what bird it might be. I have only seen the birds in
silhouette and they look like ducks of some sort.