Ducks and geese | Anatidae

Eenden en ganzen | Patos y gansos

The length of the neck decides how a species reaches its food: grazing on short waterside growth, sieving at the surface, upending with the tail in the air, or diving to the bottom — on a single pan or dam these methods often occur side by side. Besides the true ducks the family here holds goose-like forms with long legs and an upright stance, whistling ducks that are active mainly at dusk and by night and take their name from the clear flight call, pygmy geese that feed on floating water lilies, and stiff-tails that lie low in the water and display with the tail cocked. Unlike the ducks of the northern temperate zone, in most species here the sexes differ little or not at all and there is no eclipse plumage; the distinctions lie in bill and eye colour, in the size of a knob or spur, and in the pattern of the speculum. Breeding follows not a fixed season but the water: after rain, flocks move hundreds of kilometres to filling pans, where large clutches are raised quickly in a scrape lined with the female's own breast down, in a cavity, or in an abandoned nest. The female almost always incubates alone and leads the downy young, which feed themselves from the first day.