Causes of human impact to protected vertebrate wildlife parallel long-term socio-economical changes in Spain

Abstract

Obtaining information on the way human activities impact protected wildlife is not an easy task. Here, we analyze the news published by knowledgeable naturalists in Spain’s most prestigious and oldest magazine devoted to the study and conservation of nature, during a 28-year period (1982–2009). We studied the logarithm of the ratio of news published annually on direct (poaching, trapping and poisoning) versus indirect impacts (road casualties, electrocutions and collisions with infrastructure), and it turned out to be negative, strong (5% annual decrease) and statistically significant, suggesting an exponential decrease of the ratio. The decreasing trend was stronger (l = 9%) when considering only direct impacts excluding cases of poisoning that showed an increasing trend over time, showing a more realistic idea of the decreasing impact by hunters. Our modelling clearly showed that the decreasing trend in the ratio was explained by the decreasing number of hunting licences active on a yearly basis, controlled by the increase in indirect impacts. In order to validate our results, we compared our analysis with the trend shown by vertebrate admissions to a major rescue centre in eastern Spain from 1994 to 2011. The results of this second analysis showed a trend with a similar inversion of causes of impact but of a stronger magnitude (l = 15%). We discuss our findings within the context of a rapidly changing economy, evolving from a rural structure to an industrialized one, and provide some applied conservation recommendations. Indirect impacts caused by infrastructure should be approached, correcting technical problems, particularly black spots where mortality cases concentrate. Direct impacts, notably the rise in the rate of poisoning cases, need to be handled, managing the causes of increase of generalist predators, such as habitat structure, promoting the return of top predators and removing sources of subsidy, better than only fighting poaching by force.