Bonnaud, E., K. Bourgeois, D. Zarzoso-Lacoste & E. VidalCat impact and management on two Mediterranean sister islands: “The French conservation touch”.Pages 395-401 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland.
Feral cats (Felis catus) are one of the most damaging introduced species for island species worldwide. While cat control or eradication is handled with increasing efficiency on uninhabited islands, the strong bond with humans, regardless of ownership, makes cat management difficult on inhabited islands. We conducted a cat-removal programme on Port-Cros Island where both the presence of humans and their cats threaten Puffinus yelkouan, an endangered Mediterranean endemic species of burrowing petrel. The two largest French-breeding colonies of this procellariid are on the two studied islands: Port-Cros and Le Levant. The cat-removal programme was implemented on Port-Cros, with Le Levant used for comparison. Cat diet studied through scat analysis showed cats to be responsible for killing 162 ± 46 and 21 ± 4 shearwaters per cat and per year on Le Levant and Port-Cros respectively. Bird breeding parameters were monitored during seven years on Port-Cros (before and after cat removal) and three years on Le Levant. By constructing a shearwater population viability model, we calculated that the cat impact on the yelkouan shearwaters threatens the entire population in the long term and justified cat removal. We designed a conservation management plan for Port-Cros where, taking into account human presence, feral cats were live-trapped and domestic cats were sterilised. Following this two year campaign, cat predation of shearwaters ceased, followed by an increase in the shearwater breeding population. Thus, protecting seabirds from cat predation is possible, even on islands where inhabitants are notoriously reticent to any sort of cat removal programme.