Brushtail possums at a 21 ha site at Castlepoint in the Wairarapa, New Zealand, were studied with capture-mark-recapture from August 1989 to August 1994. The mean annual adult population density, based on counts of mature possums trapped each year, was 8.7 per ha and varied by only small amounts during the study period. The median survival age was 32 months (95% CI 28–39) for females and 27 months (95% CI 26–30) for males.
New Zealand aims to eradicate possums (Trichosurus vulpecula) and ship rats (Rattus rattus) nationally by 2050. This aim will require more effective tactics for locally eliminating these pests. Therefore, we explored whether possums and rats could be eliminated from large areas using pre-feeding and two applications of sodium fluoroacetate (1080) bait spaced a few months apart.
We used a long-term replicated before-after control-impact (BACI) sampling design to monitor the effect of aerial 1080 possum-control operations on common forest bird populations. Paired treatment and non- treatment sites in the Rolleston Range (East Coast, South Island) and Alexander Range (West Coast, South Island) were monitored once before 1080 treatment during winter 2012 and for three successive summers afterwards. Mammals (possums Trichosurus vulpecula, rats Rattus spp.
One of the criteria for an effective bird repellent in a pest management context in New Zealand is that possum (Trichosurus vulpecula) and ship rat (Rattus rattus) kills remain high where repellents are used in poison baits. Repellents were used in baits applied within different treatment blocks as part of a large aerial 1080 operation in November 2013 near Haast on the West Coast of the South Island of New Zealand.
In New Zealand we need to develop new control tools for the overabundant brushtail possum, which is an agricultural and environmental pest. In this study we evaluated the performance of a new microencapsulated zinc phosphide (MZP) paste (1.5% w/w nominal conc.) in a captive study and at six North Island field sites. In the captive study 14 out of 16 possums fed MZP paste bait died (87.5% kill ± 8.3% SE) with death occurring on average 165.4 minutes (± 5.5 SE) after first eating the bait.
New Zealand robins are thought to be vulnerable to poisoning by sodium fluoroacetate (1080), because individual birds found dead after aerial pest control operations have tested positive for 1080. We investigated the impacts of an aerial 1080 operation (preceded by non-toxic prefeeding) to control brushtail possums (Trichosurus vulpecula) on the survival and breeding success of a robin population at Silver Peaks, Dunedin environs, South Island, New Zealand. We monitored the survival of individual marked robins and their nesting success before and after the 1080 application.
Chew-track-cards (CTCs) are potentially a cost-effective way to estimate the relative abundance of invasive rats and possums in New Zealand, but previous research suggested that their high sensitivity may limit use to low-density populations. Using a short two-night deployment period, we compared CTC indices of rat and possum abundance with a footprint tracking rate (RTR) index of rat abundance and a wax tag bite rate index (WTI) of possum abundance in 11 forest remnants that varied widely in rat and possum abundance (RTR and WTI of 0–100% over two nights).
Transects at right angles to the shoreline are used to describe seven herbaceous, two scrub and four forest communities of the lake edge. Composition, structure, site preference and relation to lake level are given for these communities. The effect of browsing mammals on the flora and structure of mountain beech forest is shown by comparison of forest on Buncrana Island with that on the adjacent mainland. Shoreline vegetation is compared with that recorded from other areas in Fiordland.
This study provides the first quantitative comparison of methods for monitoring herbivory and growth of New Zealand beech mistletoes (Alepis flavida, Peraxilla colensoi and Peraxilla tetrapetala). Four monitoring methods-leaf maps, volume estimates visual estimates of browse and foliage density, and rePeat fixed-point photographs-were used to assess the health of 60 permanently tagged mistletoe plants in four South Island beech forests between February 1997 and February 1998.
The risks to non-target species of a newly developed bait containing either 0.15% 1080 or 0.6% cholecalciferol in a gel matrix were assessed. Very few of them ate gel bait. The safety of the gel bait is further enhanced by its placement in the purpose-designed bait station from which little spillage occurs, and which can be placed so that it is out of reach of most non-target animals. Comparative data show that nontarget species are considerably less susceptible to cholecalciferol than to sodium monofluoroacetate (1080).