Toxins, especially sodium monofluoroacetate (1080) and brodifacoum, are widely used throughout New Zealand for control of introduced mammals that are considered pests. This level of toxin use (not necessarily with these toxins) is unlikely to decline for at least 5-10 years. Ecological consequences derive both from mammal population reduction or eradication, and from using toxins as the control method.
The objective of this study was to quantify the population dynamics, morphological characteristics, and diet of rodents on Rangitoto Island (Hauraki Gulf, New Zealand) to provide information for the future development of an eradication strategy. An aerial 1080 operation to eradicate possums and wallabies was carried out two months after the study began. The effects of this operation on rodent population dynamics are discussed. Both ship rats (Rattus rattus) and mice (Mus musculus) were trapped on Rangitoto Island over a 15 month period.
Kiore (Rattus exulans) carry food to husking stations to feed, where they are sheltered from predators, competitors and rain. On four northern offshore islands of New Zealand remains of plant foods left in husking stations and in the open included seeds, leaf laminae, shoots, bark, flowers and root bases. A wide variety of animal remains were identified in husking station material, from habitats as diverse as tree tops and below the ground. All stages of both small social and large solitary insects were eaten.
Introduced mammalian predators are a major threat to New Zealand’s wildlife, including bats. Controlling these predators using traps and poison baits can reduce their impact on bat populations. However, lesser short-tailed bats (Mystacina tuberculata) are potentially susceptible to toxins used for pest control in New Zealand forests because of their broad diet and habit of feeding on the ground. Therefore, the risk of secondary poisoning should always be assessed before new toxins are used in areas inhabited by lesser short-tailed bats.
