Environmental factors influencing the habitat use of solitary and paired Torrent ducks in northwestern Patagonia, Argentina

CERON GERARDO; FERREIRO NICOLAS ANDRES

WILSON JOURNAL OF ORNITHOLOGY

WILSON ORNITHOLOGICAL SOC

Lugar: Tucson; Año: 2017 vol. 129 p. 545 - 553

1559-4491

The Torrent Duck Merganetta armata is one of the four species of ducks that may live in fast flowing rivers, and the only one inhabiting mountain rivers from Venezuela to Argentina. This study analyses physical-chemical and biological environmental variables associated to different stages of the annual cycle of this waterfowl, to test the relationship between environmental variables and the establishment of Torrent Duck territories in the southern part of its range between November 2009 and April 2011. Territories were defined as sites where a pair of Torrent Ducks was found throughout the year, while non-territories were defined as sites where solitary birds were spotted in some seasons but not year-round. The variables that best explained the habitat use by Torrent Ducks were: 1) in spring, the energy of main prey items available per square meter of river, and 2) in fall, the flow rate. A higher food availability in spring and a higher water flow in small rivers in fall were positively associated with paired Torrent Ducks territory establishment. The future assessment of breeding success in territories with contrasting levels of food and water flow may allow to determine the importance of these variables for habitat selection, and the meaning that changes in precipitation caused by climate change may have on this species.