Relationships between predation risk, diseasse and fitness in the wild rabbit: management implications

The wild rabbit (Oryctolagus cuniculus) is a high-profile prey, native from the Iberian Peninsula, the only region in the world where the two rabbit subspecies (O.c. algirus and O.c. cuniculus) currently co-exist. In this area this important prey represents a keystone species and ecosystem engineer of Mediterranean landscapes, being also the most harvested and managed small-game species, and, simultaneously, an agricultural pest in some parts of the Peninsula. The species¿ importance increased inversely with population trends over the last decades. Predation and viral diseases are two of the main factors contributing to the decline of this lagomorph, and both processes can act synergistically to affect the fitness of the species, acting mainly on juvenile rabbits. These processes are often mitigated by conservationists and hunters/game managers, through the application of expensive techniques, with results not always assured. Two major management techniques are usually applied: predator control and disease control (mainly through vaccination). The goal of this PhD thesis was to understand the relationships between predation risk, disease and fitness in juvenile wild rabbits, as a contribution to enhancing the protocol of application of these measures, and hence refine their success. Our main findings are that, by excluding mammalian predators, juvenile rabbits¿ survival (and indirectly productivity) was best improved by adding cover around warrens, which reduced the impact of raptor predation. If mammalian predators are present, then cover is still beneficial although its effect is less evident. In such cases, predation heavily affects juvenile rabbits¿ survival and predators also indirectly influence the degree of immunization by the vaccine against myxomatosis, the presence of parasites, and the mean number of emergent juveniles per adult female. Immunization of juvenile rabbits against myxomatosis was unequivocally ineffective, and therefore, current vaccination campaigns should be replaced with alternative management tools that indirectly aim at increasing population density. Finally, the observation of morphological differentiation between rabbit subspecies, with the most southern lineage (O.c. algirus) presenting smaller ears and hind feet, highlights the need to fully understand the ecological and behavioral implications of these findings, while readjusting management techniques to the subspecies in question