Brodifacoum Residue Analysis in Water, Soil, Invertebrates, and Birds after Rat Eradication on Lady Alice Island

Cereal-based pellets containing 20 ppm brodifacoum (Talon® 20P) (ICI Crop Care, Richmond) were aerially applied by helicopter over Lady Alice Island at a rate of 12 kg ha on 27 October 1994. Water samples (100 mL) were randomly taken from streams before and 2, 12, and 34 days after the poison operation. Soil samples were taken from random sites on the island before and 2, 12, 34, and 210 days after the poison operation. At these same times, 5–10 live tree weta (Hemideina thoracica White) and 5-10 live cockroaches (Blattidae) were collected by hand. An individual cave weta (Gymnoplectron spp.) and black beetles (Coleoptera) found alive on baits were also collected. The island was searched for dead birds. A morepork (Ninox novaeseelandiae Gmelin) was found 23 days after the poison application, and a juvenile kakariki (redcrowned parakeet, Cyanoramphus novaezelandiae Sparrman) 33 days after. All samples were stored at -20°C for later brodifacoum residue analysis. Five samples of water, five samples of soil, five individual tree weta, cave weta, and cockroaches Introduction