Using Brodifacoum to eradicate kiore (Rattus exulans) from Burgess Island and the Knights group of the Mokohinau Islands

Abstract

An attempt to eradicate kiore Rattus exulans from Burgess Island and the Knights Group in the Mokohinau Islands was made between August and October 1990. In August, 3 tonnes of Talon' 20 P was broadcast by helicopter from a standard monsoon bucket and 200 kg of Talon® 50 WB was broadcast manually. In October 1990 a further 200 kg of Talon' 50 WB was broadcast manually. Two kiore were snap-trapped within two days of the air drop. Subsequent snap trapping and searches have failed to detect the presence of kiore. Three harrier hawks (Circus approximans), two chaffinches (Fringilla coelebs), and one song thrush (Turdus philomelos) are the non-target vertebrate species known to have been killed. The success of this campaign is a major step forward in developing rodent eradication methods suitable for offshore islands.