Ecological cascades in Guarrizas

Since 2009 Harmusch has participated in a long-term research project in the Guarrizas region (Andújar, Jaén) dedicated to studying how the recovery of the Iberian lynx (Lynx pardinus) transforms the faunal community through ecological cascades.

The Iberian lynx, which was on the brink of extinction with only 62 individuals in 2001, now exceeds 2,000 specimens. Its return as a superpredator generates top-down effects that profoundly alter the behavior and abundance of mesopredators (medium-sized predators such as the fox, the genet, or the stone marten) and, by extension, the plant communities that depend on these animals for seed dispersal.

The team has used spatial capture-recapture models with camera traps deployed at 120 sampling points to quantify how the presence of the lynx affects each carnivore species. The results show that the stone marten (Martes foina), a generalist, suffers a reduction in density of up to 10.75 times in lynx territories, while the genet (Genetta genetta), specialized in small mammals, reduces its density by 2.20 times but manages to coexist by adjusting its activity patterns—concentrating its activity after sunset to minimize temporal overlap with the apex predator.

These data demonstrate that coexistence among predators depends not only on regulation by the superpredator (top-down), but also on prey availability (bottom-up) and the dietary plasticity of each subordinate species. The project provides fundamental evidence for the adaptive management of Mediterranean ecosystems as the lynx continues to expand its range.