Natural, human and spatial constraints to expanding populations of otters in the Iberian Peninsula

摘要: Aim To determine the relationships between otter (Lutra lutra) distribution dynamics and environmental spatial constraints over a 20-year period.Location Andalusia, southern Iberian Peninsula.Methods We synthesized data from three surveys (1985, 1995 2005) using subcatchment areas defined by hydrological barriers. Subcatchments were characterized two 'natural' (climatic orographic variables) 'human' (land use population density) gradients. In addition, we calculated contagion variables (the distance to previously occupied subcatchments percentage of within 50 km buffer) for consecutively surveyed subcatchments.Results Between 1985 2005 with otters present increased 42% 72%. Otters tended be rare or absent human-dominated areas. Anthropogenic gradients better predictors than natural ones. Human showed strong covariation, but any value in lower human impacts. Colonization new was found strongly related expansion rates slower those estimated other studies. Newly colonized located intermediate influence, while repeated absences occurred mainly where impact most severe.Main conclusions Our results suggest that recent across Andalusia is reflection large-scale improvement conditions. Otter populations survived period generalized declines appear acting as sources which neighbouring are colonized, probably aided improved water quality increases food availability. However, further into their full original range likely constrained human-impacted landscapes.