Animal Biology 61 (2011) 319–334 brill.nl/ab The presence of a “competitor pit effect” compromises wild rabbit (Orcytolagus cuniculus) conservation Sara Cabezas-Díaz ∗ , Emilio Virgós, Julián G. Mangas and Jorge Lozano ESCET, Departmento de Biología y Geología, Universidad Rey Juan Carlos, c/ Tulipán s/n, 28933 Móstoles, Madrid, Spain Abstract Wild rabbit (Oryctolagus cuniculus) populations have suffered a dramatic reduction over the last 30 years in Spain. Rabbit decline has been recurrently associated with several epizootics and habi- tat changes. The role of interspecific competition has been usually neglected. This study analyzes the effects of habitat suitability and wild boar (Sus scrofa) occurrence, a hypothetical predator and com- petitor species, on a small and isolated population of rabbits. To test this effect we used a GLM with the abundance of rabbits as response variable and wild boar occurrence as predictor. To avoid habi- tat confounding effects we included vegetation structure variables and elevation summarized in PCA factors. Rabbits showed a very restricted and aggregated distribution and a very low abundance across the study area. In contrast, wild boar was present in all sampled plots but one and showed moderate- high abundance. The three best models included both wild boar occurrence and principal component factor 2. Rabbits were located in opened Mediterranean areas where trees were small and scarce, rock cover was low and wild boar occurrence was also low. Nowadays wild boar populations are not di- rectly controlled in private lands and its hunting is forbidden in National Parks in Spain. Waiting for further research to evaluate the threshold of rabbit densities below which competitors and/or predators may prevent the recovery of rabbit populations, control of wild boars may be useful as a short-term strategy to recover small rabbit populations whenever it is linked to habitat improvements.  Koninklijke Brill NV, Leiden, 2011. Keywords Extinction; game management; herbivores; predator pit; wild boar Introduction European wild rabbit (Oryctolagus cuniculus) populations have suffered a dramatic reduction over the last 30 years in Spain (Virgós et al., 2007). Based on both Spanish and World Conservation Union criteria, these rabbits should be listed as ‘Vulnera- ble’, a status that demands a Conservation Plan Program (Virgós et al., 2007). ∗) Corresponding author; e-mail: scabezasmix@hotmail.com  Koninklijke Brill NV, Leiden, 2011 DOI 10.1163/157075511X584254