<I>Rattus rattus</I>

Measuring stoat (Mustela erminea) and ship rat (Rattus rattus) capture success against micro-habitat factors

The influence of micro-habitat on stoat (Mustela erminea) and rat (Rattus rattus) capture success was explored using trapping data collected from large scale predator control operations at the Okarito and Moehau Kiwi (Apteryx spp.) sanctuaries. Generalised linear models were used to explore the relationship between micro-habitat predictors and predator kill trapping records from individual trap sites. Our results suggest that micro-habitat information can provide useful predictors of rat and stoat capture success.

Rodent density indices from tracking tunnels, snap-traps and Fenn traps: do they tell the same story?

Comparisons were made of density indices of free-living populations of ship rats (Rattus rattus) in mixed forest in New Zealand by using footprint tracking tunnels and two kill-trapping methods. Tracking tunnels and snap-trap removal indices of rat densities showed similar trends when run on a 9 ha trapping grid, although immigration onto the grid occurred, thus violating one of the assumptions of the analysis.

Secondary poisoning of mammalian predators during possum and rodent control operations at Trounson Kauri Park, Northland, New Zealand

A poison baiting operation at Trounson Kauri Park in Northland, New Zealand using first 1080 and then brodifacoum targeted possums (Trichosurus vulpecula) and rodents (Rattus rattus, Rattus norvegicus and Mus musculus). Predatory mammals were monitored by radio telemetry during the operation. All six feral cats (Felis catus), the single stoat (Mustela erminea) and the single ferret (Mustela furo) being monitored at the beginning of the operation died of secondary poisoning following the 1080 operation.

Costs and benefits of aerial 1080 possum control operations using carrot baits to North Island robins (Petroica australis longipes), Pureora Forest Park

Large scale aerial poison operations with 1080-carrot baits are used extensively to control possum (Trichosurus vulpecula) populations in New Zealand forests for ecosystem conservation purposes and to stop the spread of bovine tuberculosis. Although various procedures have been implemented to reduce the incidence of bird kills, dead birds continue to be found after poison operations.

Distribution and abundance of small mammals in relation to habitat in Pureora Forest Park

Populations of ship rats (Rattus rattus), Norway rats (R. norvegicus), feral house mice (Mus musculus), stoats (Mustela erminea), weasels (M. nivalis), and ferrets (M. furo) were sampled with killtraps every three months from November 1982 to November 1987 in logged and unlogged native forest and in exotic plantations of various ages at Pureora Forest Park, central North Island. Mice (n=522 collected) were fewest in unlogged native forest, more abundant in road edge cutover forest, and most abundant in a young (5-10 year old) plantation.

Breeding success of New Zealand pigeons (Hemiphaga novaeseelandiae) in relation to control of introduced mammals

A 55 ha remnant of coastal native forest at Wenderholm Regional Park (near Auckland) was selected as the site for a pilot experiment to test if rat control could yield measurable benefits in increased productivity of New Zealand pigeons. Talon 50WB poison baits were used to reduce rat numbers over the summer of 1992-93. Pigeon breeding success was significantly higher (5 fledglings from 11 nests) than in preceding summers without rat control (no fledglings from 27 nests).

Population-Dynamics and Diet of Rodents on Rangitoto Island, New Zealand, Including the Effect of a 1080 Poison Operation

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.

Large-Scale Poisoning of Ship Rats (Rattus rattus) in Indigenous Forests of the North-Island, New Zealand

This paper describes the impact of nine poison operations on ship rats in four areas (35 ha to 3200 ha) of North Island forest. Poisoning with 1080, brodifacoum, or pindone killed 87- 100% of rats, based on trapping and tracking-tunnel indices. Rat populations took 4-5 months to recover. Operations to protect nesting birds should therefore coincide with the onset of nesting and be rePeated each year, although not necessarily with the same methods.

Ecology of Ship Rats (Rattus rattus) in a Kauri (Agathis australis) Forest in Northland, New Zealand

Home range dimensions and habitat use by ship rats (Rattus rattus) at Puketi, a kauri (Agathis australis) forest in Northland, were examined by live capture and radio-tracking over five weeks in September and October 1993. Home ranges of six females and five males averaged 0.86 ha in area and 174 m in length, with no significant difference in range area or length between males and females. There was substantial overlap in ranges between and within sexes.

Change in Diet of Stoats Following Poisoning of Rats in a New- Zealand Forest

The abundance and diet of stoats (Mustela erminea) were compared before and after an aerial 1080-poison operation for possums (Trichosurus vulpecula) in a New Zealand podocarp- hardwood forest. Poisoning dramatically reduced ship rat (Rattus rattus) abundance. Although rats were the main prey item of stoats before the poisoning, stoat abundance was unaffected by the operation and there was a change in stoats' diet from rats to birds. The conservation benefits and risks of undertaking such operations are not clear.