Ecology and behaviour of steamer ducks

Abstract

The three steamer ducks (genus Tachyeres) range through parts of Patagonia, Tierra del Fuego and the Falkland Islands. Criteria for separating adults of all three taxa are reviewed. The flightless forms feed and rear their young on the seacoast, whereas the Flying Steamer Ducks use mainly lakes or estuaries. Their vocalizations and territorial behaviour are similar, and all are very aggressive. Flightless adults seem to maintain permanent territories on marine coastlines while Flying Steamer Ducks often must shift when inland lakes freeze. Whether Flying Steamer Ducks are permanently paired is uncertain, but general observations suggest that permanent pairing is regular among flightless taxa. Males assist in care of the brood, but males of Flying Steamer Ducks are less regular (72% attendance) than are flightless forms (100% in Magellanic and 91% in Falkland Island forms). It is suggested that origin and dispersal of the three taxa were influenced by the limiting environmental conditions of these harsh climatic regimes.