Population fragmentation and extinction in the Iberian lynx Original Research Article

We studied the relationship between extinction frequencies of Iberian lynx subpopulations (Lynx pardinus) and their size and isolation during a 35-year period of strong geographic range contraction. At the end of this period there were fewer fragmentation events, fewer lynx populations of small size, and less isolation between them, than in simulated geographic ranges derived from a random distribution of local extinctions. Only small populations occupying <500 km2 went extinct. Local extinction in large, self-sustainable populations probably resulted from the sole action of deterministic factors, e.g. widespread prey decline. As compared with large populations, small ones experienced increased contraction per unit occupied area, which may reflect demographic unstability. The consistent effect of isolation on extinction suggests that such unstability was often prompted by reduced immigration and the subsequent disruption of metapopulation equilibrium. Several practical recommendations could be derived. Provided that habitat quality was adequate, a lynx population should avoid extinction within 35 years if it occupied an area of at least 500 km2. The persistence of small populations will also be enhanced by minimizing the distances to neighbouring populations within 30 km, and by maximizing the area occupied by these neighbours. Therefore, habitat management, or any other restoration action, directed to expand the area occupied by a small lynx population should be best located at points of its boundaries oriented towards other existing nearby populations.