Primary productivity and anthropogenic disturbance as deteminants of Upland Goose Chloephaga picta distribution in southern Patagonia

JULIETA PEDRANA; JAVIER BUSTAMANTE; ALEJANDRO RODRIGUEZ; ALEJANDRO TRAVAINI

IBIS

WILEY-BLACKWELL PUBLISHING, INC

Año: 2011

0019-1019

A species distribution may be determined by its responses to patterns of human distur-bance as well as by its habitat preferences. Here we investigate the distribution of theUpland Goose Chloephaga picta, which has been historically persecuted by farmers andranchers in Patagonia because it feeds on crops and pastures and is assumed to competewith sheep for forage. We assess whether its current breeding distribution is shaped bypersecution by ranchers or whether it can be better explained by differences in habitatprimary  productivity  and  preference  for  wetlands,  or  by  other  anthropogenic  distur-bances not associated with ranching. We built species distribution models to examine therelative effect of environmental and anthropogenic predictors on the regional distributionof Upland Goose. We performed vehicle surveys in the province of Santa Cruz, Argen-tina, in two years, surveying 8000 km of roads and recording 6492 Geese. Generalizedadditive models were used to model the presence ⁄ absence of Geese in 1-km cells. Themodels suggested that Upland Goose distribution is not currently affected by ranchercontrol, as the species is more abundant in areas with high sheep stocking levels, but it ispositively influenced by primary productivity and negatively influenced by urban areas.Anthropogenic disturbance caused by urban areas and oil extraction camps had a greaterimpact in limiting the species distribution than sheep ranching.