With eyes located on either side of their head, waterfowl have a field of vision of almost 340 degrees, enabling them to see just about everything above, below, in front of, and behind them at the same time. The saucer-shaped eyes of waterfowl also allow them to see both close and distant objects in sharp focus simultaneously.
Fulvous whistling-ducks are common in Mexico and parts of Texas, Louisiana, and Florida, as well as in central and southern Africa. Nobody knows how these two populations became established, but one likely explanation is that members of the African population were carried across the Atlantic to North America by strong westerly winds.
The oldest known duck to be taken by a hunter was a canvasback harvested at the ripe old age of 29. The oldest known goose to be taken by a hunter was a Canada goose of the same age.
In some waterfowl species, including lesser scaup, common eiders, and Canada geese, two or more broods may congregate in a crèche under the supervision of several hens (in the case of ducks) or sets of parents (in the case of geese). In eiders, hens take turns watching ducklings while others feed. The babysitting hens are known as "aunts."
Ducks usually migrate at an altitude of 200 to 4,000 feet but are capable of reaching much greater heights. A jet plane over Nevada struck a mallard at an altitude of 21,000 feet—the highest documented flight by North American waterfowl. And a 1954 climbing expedition to Mount Everest found a pintail skeleton at an elevation of 16,400 feet.
Several ducks are Holarctic in distribution, meaning they occur throughout the northern hemisphere (encompassing North America and Eurasia). These birds include northern shovelers, northern pintails, mallards, gadwalls, green-winged teal, common goldeneyes, and greater scaup.
The only North American dabbler or diver that also breeds in South America is the cinnamon teal. Fulvous and black-bellied whistling-ducks also breed on both continents.
In one study on the survival of wood duck ducklings, great blue herons ate 10 of 48 ducklings fitted with radio transmitters. When a researcher discovered that one of the transmitter signals was originating from a live heron, the biologist used his receiver to track the heron to its roost site, where it regurgitated the transmitter.
Buffleheads nest in holes made in hollow trees by nesting flickers, a common species of woodpecker. Pileated woodpeckers create many of the nesting sites used by wood ducks and other larger cavity-nesting ducks.
TOUCH OF GRAY
People may not be the only ones who "gray" as they grow older. In a banding study of 1,700 redheads on the Laguna Madre of Texas, researchers found that the amount of gray feathers on a hen's head may provide an accurate prediction of age. Some hens eventually have so many gray feathers that their head appears almost white.