All About Birds.
The Black-bellied Whistling-Duck reaches the United States only in the very southern parts. Its long neck, long legs, black belly, and white wing patch make it a distinctive-looking waterfowl.
The whistling-ducks were formerly known as tree-ducks, but only a few, such as the Black-bellied Whistling-Duck actually perch or nest in trees. They look most like ducks, but their lack of sexual dimorphism (male & female look-alike) & , relatively long-term pair bonds, and lack of complex pair-forming behavior more resembles geese and swans.
Pretty neat, huh? We're hoping they nest and stay around for a while.