Identifying native and exotic predators of ground-nesting songbirds in sub-Antarctic forests of southern Chile

BRETT M. MALEY; CHRISTOPHER B. ANDERSON; KIRK STODOLA; AMY D ROSEMOND

ANALES DEL INSTITUTO DE LA PATAGONIA

UNIVERSIDAD DE MAGALLANES

Lugar: PUNTA ARENAS; Año: 2011 vol. 39 p. 51 - 57

0718-6932

Birds constitute the most diverse and abundant group of vertebrates in the austral archipelago of southern South America; yet key aspects of their ecology such as nesting success and predators are little known. The American mink (Neovison vison) was introduced to Tierra del Fuego in the 1940s and expanded its range south of the Beagle Channel into the Cape Horn Biosphere Reserve by 2001. As a new top predator, the invasive mink may have signiicant impacts on naïve avian species, including some forest Passeriformes that nest on the ground. To determine the identity and effect of ground nest predators, we conducted an artiicial nest experiment and assessed the impact of predators on daily survival rates of artiicial nests in three different habitat types (anthropogenic shrublands, beaver meadows, and forests). We found that 65% of nests were depredated (40% due to native Southern House Wrens [Troglodytes musculus] and 25% from mink). However, we discovered that mink were the cause of 53% of the nest failures in the anthropogenic shrubland. These findings demonstrated that both native and exotic predators affect nesting success of subantarctic forest avifauna, but the influence of an invasive top predator, the mink, constitutes a new threat that will likely affect both nesting success and parental survival.