Patterns and causes of non-natural mortality in the Iberian lynx during a 40-year period of range contraction

摘要

We analyse the spatial and temporal variation in non-natural mortality during a 40-year period of strong contraction of the geographic range of the Iberian lynx (Lynx pardinus), which shrank from 40,600 to 22,300 km(2). We recorded 1258 lynx deaths, an average of 31.5 losses per year over the study period. Given the reduced lynx population size, especially later in the period (around 1100 individuals), this level of non-natural mortality may have contributed significantly to the quick decline of the Iberian lynx. Non-natural mortality was not spatially correlated with, and probably did not shape the pattern of, relative abundance of lynx across its core range, but may have reduced its absolute density. Lynx losses were caused mainly by traps set not only for predator control but also for rabbits (Oryctolagus cuniculus), the lynx's staple food. We did not find evidence that non-natural mortality was higher in small lynx populations through edge effects. The highest mortality levels were recorded in regions where small game was a valuable economic resource compared with other activities. Mortality decreased throughout the period because of changes in the prevailing game regimes rather than because of legal protection. The Iberian lynx is now critically endangered and effective protection should be urgently enforced, especially in small game estates, which are environmentally favourable for rabbits but risky for lynx due to predator control. Lynx reintroductions would be better attempted in traditional rabbit hunting areas. Some big game estates where small game is not exploited and predators are not controlled may be good candidates for lynx reintroduction too, provided that habitat is managed towards a suitable interspersion of woody cover and grassland