A field trial of a new rat poison, compound S-6999, on brown rats
- Forest Research Institute, New Zealand Forest Service, Rotorua
- Present address: Animal Ecology Division, D.S.I.R., Lower Hutt
The problem of introduced rats endangering the survival of rare birds is a very real one. This is shown by a recent depressingly long list of birds known to have become extinct since 1600, prepared by Vincent (1965) of the International Union for the Conservation of Nature and Natural Resources. Vincent shows that rats and other introduced predators have been directly responsible for the extinction of at least 30 species and subspecies of birds in that time, and probably of twice or three times that number. Several rare species and subspecies of birds surviving on New Zealand's off-shore islands are likewise in danger of extermination by rats.
A recent survey of Big South Cape Island off Southwest Cape, Stewart Island (Blackburn 1965) revealed that six species and subspecies of birds have either been exterminated or driven close to extermination on this island by rats during the past two years. Merton (1965) noted that the black rat (Rattus rattus) was responsible.
Following an ecological study of the brown rat (Rattus norvegicus) on Mokoia Island, Lake Rotorua (Beveridge and Daniel 1965), the opportunity arose, through the courtesy of the Australian manufacturers, to conduct acceptance trials of a unique new rat poison called "Raticate" which contains 1 % of the organic compound S-6999 w./w. in maize. Trials with compound S-6999 (also called norbormide) to control brown rats in the United States have been described by Crabtree et al (1964). The present paper describes two acceptance trials with brown rats carried out on Mokoia Island from November 1965 to January 1966.