The introduced silver pheasant Lophura nycthemera (Phasianidae) in Isla Victoria, Patagonia Argentina: abundance, group structure, activity patterns and association to anthropic disturbance

MARTIN ALBARRACIN, VALERIA LETICIA; AMICO, GUILLERMO; NUÑEZ, MARTIN ANDRÉS

El Hornero

Asociación Ornitológica del Plata

Lugar: Buenos Aires; Año: 2017

0073-3407

Phasianidsare one of the groups of introduced birds with greatest impact on nativeecosystems. In Patagonia there are several introduced phasianid speciesestablished or in process of establishment, thus it is relevant to know theirimpacts on ecosystems. Silver pheasant was introduced to Isla Victoria in the1950s and successfully established all over the island. The aim of this work isto study the population of silver pheasant on Isla Victoria in terms ofabundance and association to anthropic disturbance as a first step to know thepotential impact of the species in the ecosystem. We conducted camera-trapping(1253 camera-days) and direct counts in linear transects 500 m long (n = 10) intwo areas with different level of anthropic disturbance: high (n = 4) and low(n = 6). Using camera-trapping data we estimated an index of relative abundanceto compare habitat use between areas. We used the distance-sampling approach toestimate the population density of pheasants with the data from direct counts.Silver pheasant used much more frequently areas with a high degree ofdisturbance, suggesting that the presence of environments with these traitscould facilitate their establishment and spread in Patagonia. Populationdensities of silver pheasant (in areas with high and with low degree ofdisturbance) were greatest than those reported from their native distributionarea, showing that pheasants had a great success on Isla Victoria. Thisabundance, together with distinctive traits such as body size, foraging habitsand social behaviour can shape their interactions with native species anddetermine their effect on native communities.