PROJECT DESCRIPTION
BACKGROUND
Predation by the black rat (Rattus rattus) is threatening the world’s largest population of Mediterranean Shearwaters (Puffinus yelkouan) – 9 991 to 13 424 pairs out of a global population of 15 337 to 30 519 pairs. On Tavolara, Shearwaters can only successfully reproduce at a reduced number of nests, located in caves in rat-free high cliffs. The same threats also affect other bird species. The presence of alien plant species (in particular Carpobrotus edulis and C. acinaciformis) on the island also threatens the conservation of habitats and species, as does the presence of a colony of wild goats. Tackling these biological threats is made more difficult by a lack of awareness among the local population of the importance of the threatened species, and of the risks associated with the introduction of alien species.
OBJECTIVES
The project's objectives were:
- Eradication of R. rattus and house mice (Mus musculus) from Tavolara and three smaller islets using rodenticide baits, which will be distributed from the air, except along the coast and in the few inhabited areas of Tavolara. The adopted method will not pose risks of environmental pollution;
- Preparatory scientific actions (monitoring of rodents, non-target species at risk, P. yelkouan and other target species) and communication with the local community (meetings, educational activities, volunteer involvement), as well as to a wider audience (website, webcam in P. yelkouan nests, publication in journals);
- Preliminary investigations will be carried out to assemble data, which can be provided to the competent authorities and used to inform the public. Careful monitoring will assess in detail the benefits of the project, and weigh them against any adverse effects. The eradication project will also be submitted to peer review;
- During the eradication phase, biosecurity measures, to reduce the risk of subsequent re-invasion, will be implemented;
- Eradication of Carpobrotus from Tavolara by manual uprooting. At present, the plant is not widespread, but it has huge potential for expansion. In order to involve the local community directly in the project, volunteers will be recruited. The project will also assess the risk of invasion by other alien plants, and will carry out eradication work if necessary;
- Control of wild goats on Tavolara by capture and free conveyance to breeders, and the drafting of action plans for post-project management of the goat population.
RESULTS
Tavolara’s population of yelkouan shearwaters (P. yelkouan) is thought to be one of the largest in the world. The LIFE Puffinus Tavolara project’s rat eradication should improve this population as well as the situation of other important vertebrate species – reptiles and birds – on the island. The project’s key results were as follows:
- The rat eradication was implemented satisfactorily and the first positive results were seen in the improved status of vegetation at the Spalmatore site and in the presence of terrestrial species of mammals and reptiles not previously observed during the project;
- At the final stage of the project, a slight improvement was seen in the reproductive success of yelkouan shearwaters after the rat eradication;
- No sign of rats was found following the eradication up to, and after, the project’s end;
- Almost all of the several species of Carpobrotus present were removed from the island, enhancing the populations of other plants, some of which are listed in Annex II of the EU’s Habitats Directive;
- Project staff carried out several activities aimed at increasing awareness on the issue of alien species, including production of a brochure on how to create Mediterranean gardens; and
- In an awareness-raising activity not originally planned, project staff informed citizens about the problem of light pollution and how to rescue young yelkouan shearwater fledglings in order to reintroduce them into the wild, far away from danger. Some young shearwaters, disoriented by the light pollution of the Olbia city, have been rescued in summer 2018 and released in safe conditions.
- Etruscan shrews and young tortoises have been found after the rat eradication testifying immediate positive effects of the removal of rats for the ecosystems on Tavolara.
