Those who have had the opportunity to venture to the Gulf Coast to hunt, bird watch or just grab some R&R may have encountered some long, slender ducks locally known as squealers. Black-bellied and fulvous whistling ducks are most common in Mexico and Latin America where they are known as pichichi or pato maizal and pijia or pato silvon.
There are eight species of whistling ducks in the world, but only two-the black-bellied and fulvous whistling ducks-occur in the United States. Scientists consider whistling ducks more closely related to geese and swans than to the "true ducks." With their long legs, long necks, bone structure and erect stance, they certainly look more like geese than like ducks. As with geese and swans, the plumage of both sexes of whistling ducks are very similar. They only have one molt (in contrast to two molts in the "true ducks"); both parents share in the brooding of the young; and pairs mate for life.
They also are distinguished by their appearance and behaviors in the field. Black-bellied whistling ducks fly slowly in shapeless formations. In flight, they show long necks, trailing legs, and broad wings, but the most distinguishing feature is the contrasting black and white between the upper and lower wings. When standing or perching, the most striking features are the bird's namesake stark black belly and sides, along with the red bill and pink feet. Biologists recognize two subpopulations of black-bellies.
The northern population breeds from central Texas through coastal Mexico and Central America. The southern population breeds from Panama south into Argentina. Like most of their tropical counterparts, black-bellies do not show strong migratory patterns; instead, they move relatively short distances in response to habitat availability within their breeding range.
Black-bellies breed during their first year of life, establishing lifelong pair bonds during their first winter. Nest initiation occurs from April through August, a period approximately one month longer than prairie nesting ducks. Black-bellies nest in tree cavities and, similar to wood ducks, also have adapted to nesting in boxes. Where tree cavities are lacking, black-bellies will nest on the ground, often in grasses at the base of small trees or shrubs. Females lay an average of 13 eggs and both sexes incubate the eggs. Experiments have revealed that removal of either the female or the male during incubation results in abandonment of the nest. Apparently, participation of both the male and female is necessary for the nesting attempt to be successful. Black-bellies enjoy relatively high nest success rates (an average of 45 percent) compared to prairie nesting ducks. Most nest failures are caused by raccoons, rat snakes and golden-fronted woodpeckers.