Effectiveness of traditional wild rabbit restocking in Spain

Since myxomatosis, around half a million rabbits are restocked annually in France and the Iberian Peninsula. The effectiveness of this approach to restoration is still unknown. In this study, the efficacy of traditional restocking was evaluated by marking rabbits with radiocollars and reproducing the methodology usually employed in Spain. The estimated mean survival rate for the first 10 days after release was very low (<3%). Most of the tagged rabbits were dead within three months. Causes of mortality included injuries, disease, and predation (especially by red foxes, Vulpes vulpes). The deaths were mainly within the first week after release, a period that could be considered critical for the establishment of the animals. Male rabbits were more affected by diseases, whereas females were preyed upon more often. For both sexes, average dispel sal distance was low (435 m from the release place). We suggest that survival of introduced rabbits could be increased (21%) by disturbing carnivores within the restocking area. A short period in captivity prior to release (2-3 weeks) increased rabbit survival rates (40%), by allowing us to remove diseased animals (mainly affected by myxomatosis). Assuming the existence of a 'predator pit' in some populations of rabbits, the traditional rabbit restocking is not an effective method of increasing the most important prey for the vertebrate ecosystem in the Iberian Peninsula, although some improvements could be made.