Role of landscape elements on recent distributional expansion of European Starlings (Sturnus vulgaris) in agroecosystems of the Pampas, Argentina

Abstract

Previous studies of European Starlings in Argentina have focused on identifying biological aspects correlated with establishment of new populations in urban and suburban areas. Starlings have recently invaded rural areas in the Pampas. To understand the factors involved in the recent expansion of European Starlings into these rural habitats, we investigated how expansion patterns were associated with season, proportion of crop fields, distance to woodlots, and distance to small and big urban centers in agroecoystems of the Pampas. We surveyed 392 fields during 2011-2013 to collect data on presence of starlings and landscape features. We found that the range of European Starlings has expanded by a total area of ∼65,000 km2 since 2005, at a linear range expansion rate of 22.2 km per year. Generalized linear mixed model analysis revealed that presence of European Starlings was significantly related with reduced distances to nearest small urban area. Our findings indicate that range expansion of European Starlings into rural areas of Argentina may follow a neighborhood diffusion pattern, by which well-established populations act as sources of individuals that disperse short distances into nearby favorable areas. In absence of human control, this species is expected to continue its spread and population increase.