Anatra vapore volante

Identificazione

Though they are the smallest of the four Tachyeres species, flying steamer ducks share similar plumage traits with other steamer ducks including brown head and neck feathers with white stripes stretching from their eyes to the napes of their necks, and brown-gray gradient body feathers. Their underbellies are mostly white, and their feet are orange. Female flying steamer ducks have smaller bills relative to males that are orange with black tips, while males have darker gray bills with slight yellow accents. Flying steamer ducks are also sexually dimorphic to the extent that males are heavier but have smaller cranial elements and wingspans than females. Males and females both possess cornified orange carpal knobs on the proximal part of the carpometacarpus bone, and these knobs are used in display as well as interspecies and intraspecies combat by males.<p>Sexual dimorphism can also be observed in the duration and pitch of their various calls, which sound much like grunts. The females’ grunts have been described as lower pitched than the males’ grunts, and usually occur in rapid succession of similar pitch. Males have three distinct grunts that have been described as whistle-like, including a ‘rasping’ grunt, a ‘ticking’ grunt, and a ‘sibilant’ grunt.<p>Flying steamer ducks undergo three molts per annual cycle, and these molts vary widely with geographic location. The wear and degradation on the primary and secondary feathers of observed flying steamer ducks varies depending on the location and flight behavior of the individuals.

Tassonomia

Nome scientifico

Tachyeres patachonicus

Autorità

(King, PP, 1831)

Ordine

Anseriformi

Famiglia

Anatidae

Genere

Tachyeres

Areale e habitat

Migrazione

Complete migrants

Conservazione

Tendenza della popolazione

declining