Conservation of otter (Lutra lutra) in a Mediterranean area: the importance of habitat quality and temporal variation in water availability

摘要

This study analyses quantitatively the association between habitat characteristics and annual variationin water availability on otter (Lutra lutra L.) distribution in a large Mediterranean area (13717 km(2)) in southernSpain.There was a strong positive correlation between habitat quality, estimated after the two first components of aprincipal component analysis of a matrix of habitat variables x sites, and an index of otter presence/absence, otterpresence being most commonly associated with unpolluted and undisturbed sites surrounded by woodland.After univariate analysis, the main freshwater habitat features were statistically different between sites with ottersand sites lacking them. In general, otters occurred in medium-sized fluvial habitats, with high bankside vegetationcover, unpolluted, with low or very low human disturbance and surrounded by forests or dehesas (Mediterraneanlikesavannah).Water availability, inferred from the water balance, strongly influenced otter distribution and the type of waterbody used the most. As water availability increased so did the otter distribution range and during these: periods theytended to colonize low-order streams. During periods of water shortage, otters were usually found in high-orderstreams and reservoirs, the only sites that kept water.This work shows that otter distribution in Mediterranean areas is strongly influenced by two factors - maninducedhabitat degradation and natural variability in water availability. The addition of the second factor to the firstone introduces additional risks to the survival of otter populations in Mediterranean areas compared with morenortherly and humid areas. Copyright (C) 2001 John Wiley & Sons, Ltd.