Eradication of Pacific Rats (Rattus exulans) from Whenua Hou Nature Reserve (Codfish Island), Putauhinu and Rarotoka Island, New Zealand

Pacific rats (Rattus exulans) were eradicated from three islands in southern New Zealand in 1997 and 1998. In August 1998, two aerial applications (9.7 kg/ha and 9.4 kg/ha) of 2 g Agtech cereal pellets containing 20 ppm brodifacoum, were made over the whole of 1396 ha Codfish Island (Whenua Hou Nature Reserve) for the eradication of Pacific rats (Rattus exulans). Preparation for the eradication included the eradication of Pacific rats from 144 ha Putauhinu in August 1997 so that a second population of a fernbird (Bowdleria punctata wilsoni) endemic to Codfish Island could be established there. A bait drop was also carried out on 88 ha Rarotoka (Centre Island) on the same day as Putauhinu, to eradicate Pacific rats as the first step in the restoration of that island. A single drop of 12 kg/ha of Talon 20P cereal bait containing brodifacoum at 20 ppm was used for the Putauhinu and Rarotaka eradication. To protect the fernbirds on Codfish Island which were at risk from the aerial bait drop, a ground bait station network on a 50 m x 25 m grid covering 37 ha was set up and operated in conjunction with the aerial drop. With no sign of rats having been detected for two years after the respective bait drops, the three eradications have been declared successful.

AuthorMcClelland, P. J.
Secondary titleInternational Conference on Eradication of Island Invasives
PublisherIUCN Invasive Species Specialist Group
Control methodBaiting