Five herbivorous introduced mammals are sympatric in the central Southern Alps. All of these species have the potential to affect conservation values, yet the Department of Conservation at present monitors and mitigates the impacts of only one. We outline ecological arguments for multi-species management of sympatric herbivore pest impacts and use the two- species system of sympatric thar and chamois to highlight the need for multi-species management of the central Southern Alps alpine pest community.
A single five night pulse of sodium monofluroacetate (0.15% 1080) applied in bait stations at two different spacing intervals, 100 and 200 m, along forestry roads in New Zealand beech forest, killed all four of the resident radio-tagged stoats (Mustela erminea) and all three of the resident radio- tagged wild house cats (Felis catus) by secondary poisoning. Gut contents of predators indicated that house mice (Mus musculus), ship rats (Rattus rattus) and bushtail possums (Trichosurus vulpecula) were important sources of the toxin.
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).
Brown kiwi (Apteryx mantelli) in central Northland have been monitored for up to 32 months of sustained exposure to brodifacoum poison. The cereal baits were placed in bait stations to target brushtail possums (Trichosurus vulpecula). Annual survival of 55 radio-tagged adult kiwi in two poisoned forest patches has been high (95.9%), and similar to that in two nearby unpoisoned forest patches and in the patches before poison was used (95.3%).
To assess the effect of possum browse on plant growth, an index of the amount of foliage on about 50 trees of Fuchsia excorticata and the number of trees that died or were completely defoliated was measured at five sites in South Westland over 5 years. This index was compared to possum density indices taken at each site each year. At one site, possums were reduced from a high density about 6 months before the final measurement. The degree of defoliation of fuchsia was significantly related to the density of possums at each site.
Two morphological types of brushtail possum (Trichosurus vulpecula) were introduced to New Zealand: smaller, grey possums from mainland southeastern Australia, and larger, black possums from Tasmania. Analysis of patterns of allozyme variation and allele frequencies of present-day possum populations in New Zealand and southeastern Australia indicates that populations comprised predominantly of black possums remain genetically similar to possums in Tasmania, whereas predominantly grey populations are genetically closer to Victorian and New South Wales possums.
A knowledge of the sensitivity of the brushtail possum (Trichosurus vulpecula) to 1080 poison is important as a basis for planning effective control campaigns. This study assesses the effects that experimental procedure may have on determining the LD50 of 1080 for brushtail possums and reports on the variation in sensitivity within and between different populations of the species in Australia, where it is indigenous. LD50s obtained ranged from 0.39–0.92 mg kg-1, with 95 % confidence limits of from 0.29–1.20 mg kg-1.
North Island robins (Petroica australis longipes) and tomtits (P. macrocephala toitoi) are at risk of being poisoned during pest control operations in New Zealand. Robins are deterred from feeding on diets containing primary repellents (e.g. blue colour, d-pulegone) and secondary repellents (e.g. illness-inducing materials such as anthraquinone, which induce taste aversions). We tested, with wild robins, primary and secondary repellents surface-coated onto dough baits, over 4 days on Tiritiri Matangi Island.
Dama wallabies (Macropus eugenii) are an introduced pest in New Zealand requiring control. Historically, sodium fluoroacetate (1080) has been used to control wallabies but there is increasing resistance to this method of pest control. Pen trials have shown that Feratox® cyanide pellets are an effective and humane toxin for use on dama wallabies. The aim of this study was to test the effectiveness of these cyanide pellets in field trials for controlling dama wallabies.
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.