Eradication of rabbits (Oryctolagus cuniculus) by poisoning on three islands of the subantarctic Kerguelen Archipelago

Abstract

In order to rehabilitate islands of the Kerguelen Archipelago degraded by the rabbit (Oryctolagus cuniculus), a program of eradication by poisoning was implemented from 1992 onwards on three islands: Verte Island (148 ha), Guillou Island (145 ha) and Cochons Island (165 ha). The poison used was a first-generation anticoagulant, chlorophacinone (0.05 g kg –1 ) on wheat bait treated to prevent germination. Bait was applied during the winter (July) in 1992 on Verte Island, in 1994 on Guillou Island and in 1997 on Cochons Island. Before poisoning, there were about 1250–1300 rabbits on Verte and Guillou Islands (9 rabbits per hectare) and 2600 rabbits on Cochons Island (16 rabbits per hectare). In total, about 1200, 1300 and 1600 kg of bait were distributed respectively on each island. Fifteen days after poisoning commenced 90% of the rabbits had died on Verte and Guillou Islands and 80% on Cochons Island. Two months later, only a small number of individuals survived; these were eliminated by shooting or poisoning, except on Cochons Island where a second bait application was necessary in the winter of 1999. No rabbits or tracks have been observed since 1994 on Verte Island, and since 1996 on Guillou Island, and the elimination of the last individuals is under way on Cochons Island. Inadvertent poisoning of non-target species by primary poisoning mainly involved two species of native birds (Larus dominicanus, Anas eatoni) and the mouse (Mus musculus) on Guillou and Cochons Islands. The cat (Feliss catus) on Guillou Island was the only species killed by secondary poisoning. The results are compared with other rabbit-eradication operations using a second-generation anticoagulant.