Looks Like a Duck, Walks Like a Duck

But doesn't quack like a duck. Instead, these ducks whistle, sort of like a tweet. They are very social and hang out together in large groups. Together they tend to make a lot of noise.

 

Three black-bellied whistling ducks (Dendrocygna autumnalis) on a small fishing/observation pier beside Elm Lake, Brazos Bend State Park

 

en.wikipedia.org/wiki/Black-bellied_whistling_duck

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