Population Declines of Predatory Birds Coincident with the Introduction of Klerat Rodenticide in North Queensland

Abstract

Rodents are significant pests of crops in sugar-producing areas in North Queensland and, consequently, rodenticide is applied to canefields as a control measure. Klerat, a second-generation anticoagulant (active constituent brodifacoum), is the only rodenticide registered for use in sugarcane in North Queensland. Regular monitoring of raptors over 21 years has revealed a major decline in the breeding populations of several rodent-eating species in the Herbert River district since 1992, coincident with the introduction of Klerat in that year. The raptor declines may be a result of secondary poisoning, a decrease in prey availability, or a combination of both. Habitat loss may also be an important contributing factor.