Survival and space use of a restocked Iberian rabbit population in a semi-natural enclosure

Abstract

Restocking is widely used to recover depleted wild rabbit, Oryctolagus cuniculus, populations in the Iberian Peninsula. However, in general, it’s costly and unsuccessful. In this work, we developed a wild rabbit restocking protocol based on recommendations from existing literature to enhance its success. We released 75 Iberian rabbits, Oryctolagus cuniculus algirus, in a 1.7-ha restocking park, a fenced semi-natural enclosure, with similar resources as the surrounding area, in Monchique, southern Portugal. We tracked 22 radio-collared rabbits (sex ratio 1:1) for 6 months. We released some rabbits inside warrens, and others in shrub patches. After a 72-day acclimation period, we opened the restocking park passages to allow the rabbits to disperse. We then accessed rabbit survival and space use. We found that survival rates stabilised 74 days after restocking, with an estimated probability of survival at the end of the study of 35.4%. Predation by birds of prey was the primary cause of death. Regarding space use, the restocked population took 96.364 ± SE 12.615 days to stabilise home ranges. After the acclimation period, the maximum distances travelled by rabbits significantly increased. However, before and after the opening of the passages, the home ranges remained within the limits of the restocking park, indicating that the surviving rabbits settled within the enclosure. Rabbits released within warrens had significantly smaller core areas, while those released in shrubs exhibited more ranging behaviour. Considering our findings, we recommend implementing several measures to improve similar rabbit restocking programs.