Comportamiento territorial y reproductivo del pato de torrentes (Merganetta armata) en la Cordillera Central de Colombia

Territorial and reproductive behavior of the Torrent Duck (Merganetta armata) in the Central Andes of Colombia

Abstract

The Torrent Duck (Merganetta armata) inhabits torrential rivers throughout the Andes. Several subspecies have been described, but there is no agreement on their validity or their conservation status. Although the species is not threatened, two subspecies, including the one inhabiting the Colombian Andes, may be threatened. We describe territorial and reproductive behavior and estimate population density of Torrent Ducks in the Otún River, Central Cordillera of Colombia. We found seven territorial pairs in a 3.7 km stretch of the river and a floating population of nonterritorial individuals. Mean territory size was 630 m, with a range of 200-975 m. We observed 25 territorial encounters and identified three categories of intensity of ritualized agonistic displays. In the highest category, ducks had physical contact. We observed the formation of a new territory, the pair formation process, and copulation. Our results revealed smaller territories and higher population densities than a previous study in the same site. This population increase may be the result of natural population fluctuations, or of habitat improvement owing to continued protection. Although we found high local population densities in the Otún River, populations may be vulnerable due to their small size and fragmentation because they are restricted to the upper parts of river basins and isolated as a result of habitat degradation at lower elevations.