High occupancy of non-native carnivores in riparian ecosystems along an urban gradient in Chile
摘要
Urbanization represents one of the most extreme forms of land cover change. However, riparian ecosystems can play a key role in providing habitat and maintaining functional connectivity across urban landscapes. Here, we compared carnivore occupancy in riparian ecosystems between urban and surrounding rural areas in a city of southern Chile. To this end, we deployed camera traps at 52 sites located along the rivers of Valdivia, Chile, and adjacent rural zones. We then used single-species, single-season occupancy models to evaluate the responses of native, invasive, and domestic carnivores to urbanization. Excluding small rodents, we recorded three and eight native mammalian species in urban and rural areas, respectively. Occupancy models revealed contrasting responses among species: the kodkod (Leopardus guigna), a small native felid, showed lower occupancy in urban areas than in rural areas, but these patterns were mostly explained by decreasing riparian forest cover, whereas the dogs and cats were positively associated with different urbanization metrics. The occupancy of the invasive American mink (Neogale vison) was unrelated to urbanization and was instead influenced by riverbank position, with higher occupancy at the water’s edge. Our findings indicate that urbanization alters the composition of riparian carnivore assemblages, which become dominated by domestic and invasive species. The high occupancy of non-native carnivores may thus compromise the potential of urban riparian ecosystems to serve as functional corridors for native species.