Science and Policy Group

Dunedin, New Zealand

Science and Policy Group

Dunedin, New Zealand
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Cowan P.,Landcare Research | Crowell M.,Science and Policy Group
New Zealand Journal of Ecology | Year: 2017

Non-target risk from the use of vertebrate toxins for pest control is an ongoing issue globally. In New Zealand, toxic bait for aerial control of possums and rodents is dyed green and contains cinnamon oil, both of which are thought to reduce the risk that birds will eat the bait. It has been suggested for some time that blue dye may be a more effective feeding deterrent than green dye. While both green and blue dye reduce the risk that birds will feed on bait, the available evidence is not sufficiently strong to suggest a significant improvement in repelling birds by switching from green to blue. Cinnamon oil, at the nominal concentration in bait, may have some bird repellent effects, but these are likely to depend on its origin (bark or leaves) and the freshness of the bait (as it evaporates relatively quickly from bait after manufacture). Bait colour, including ultraviolet, is also an important cue in avoidance learning by birds and should be considered in more detail in future studies of specific bird repellent additives to bait for possum and rodent control. Further research is needed to optimise the use of visual cues in bait, both for their inherent repellency (e.g. green vs blue; optimal concentration of dye) and for their effectiveness in promoting avoidance learning. It would also be worth investigating an alternative compound to cinnamon as a mask for 1080; ideally such an alternative would have enhanced stability and bird repellent properties. © New Zealand Ecological Society.


Pryde M.,Science and Policy Group | O'Donnell C.F.J.,Science and Policy Group
New Zealand Journal of Ecology | Year: 2017

Introduced mammalian predators, in particular rats (Rattus spp.), are a major threat to New Zealand bat populations. Aerial application of the toxin sodium monofluoroacetate (1080) is currently the most costeffective method of controlling rats across large spatial extents. Lesser short-tailed bats (Mystacina tuberculata) may be vulnerable to secondary poisoning from 1080 because they feed on invertebrate prey on the ground that may have consumed toxic bait. We monitored individually marked bats before, during, and after an aerial 1080 operation in the Eglinton Valley, Fiordland, in December 2014 from a population that has been monitored since 2008. No symptoms of sub-lethal exposure in free ranging bats were detected and survivorship was high: 764 of the 771 marked bats (99.1%) recorded in the pre-monitoring period were still alive one week after toxin application and a record number of 1731 marked bats were recorded emerging from a single roost tree in January 2015. One bat pup was found dead under a roost tree and 1080 was detected in muscle tissue. Any immediate impact of 1080 was assessed as minimal because the calculated annual survival rates were high (91.5%). We conclude that survival of the population was likely enhanced by the large scale 1080 operation. © New Zealand Ecological Society.


O'Donnell C.F.J.,Science and Policy Group | Weston K.A.,Science and Policy Group | Monks J.M.,Science and Policy Group
New Zealand Journal of Ecology | Year: 2017

Alpine zones are threatened globally by invasive species, hunting, and habitat loss caused by fire, anthropogenic development and climate change. These global threats are pertinent in New Zealand, with the least understood pressure being the potential impacts of introduced mammalian predators, the focus of this review. In New Zealand, alpine zones include an extensive suite of cold climate ecosystems covering c. 11% of the land mass. They support rich communities of indigenous invertebrates, lizards, fish, and birds. Many taxa are obligate alpine dwellers, though there is uncertainty about the extent to which distributions of some species are relicts of wider historical ranges. The impacts of introduced mammalian predators are well described in many New Zealand ecosystems, though little is known about the impacts of these predators on alpine fauna. Here we review the importance of alpine habitats for indigenous fauna and the impacts of introduced mammalian predators; and develop a conceptual model explaining threat interactions. Most evidence for predation is anecdotal or comes from studies of species with wider ranges and at lower altitudes. Nevertheless, at least ten introduced predator species have been confirmed as frequent predators of native alpine species, particularly among birds and invertebrates. In the case of the endangered takahe (Porphyrio hochstetteri) and rock wren (Xenicus gilviventris), stoats (Mustela erminea) are primary predators, which are likely to be impacting significantly on population viability. We also document records of mammalian predation on alpine lizards and freshwater fish. While the precise impacts on the long-term viability of threatened species have not been evaluated, anecdotal evidence suggests that predation by mammals is a serious threat, warranting predator control. Future research should focus on predicting when and where mammalian predators impact on populations of indigenous fauna, furthering our understanding of the alpine predator guild particularly through adaptive management experiments, and exploring interactions with other threats. © New Zealand Ecological Society.


O'Donnell C.F.J.,Science and Policy Group | Robertson H.A.,Science and Policy Group
Notornis | Year: 2016

We collated and reviewed 4179 records of the historic and contemporary distribution of the endangered specialist wetland bird, the Australasian bittern (matuku, Botaurus poiciloptilus), in New Zealand, to assess its current status and trends in its distribution across major habitat types. We mapped distribution in 5 time periods (pre-1900, 1900?1949, 1950?1969, 1970?1989, post-1990). We found that Australasian bittern are currently found throughout New Zealand with strongholds in Waikato, Northland and Auckland regions (46% of records) in the North Island, and Canterbury and West Coast (22%) in the South Island. They occur widely in freshwater and brackish riverine, estuarine, palustrine and lacustrine habitats. Australasian bittern were abundant (records of groups <100 birds) in Mori and early European times, but historical maps indicate their range appears to have been reduced by c. 50% over the last hundred years, with the most dramatic shrinkage in range occurring post-1970. Marked declines in occupancy began in Otago, Canterbury, Waikato, Wellington and Auckland regions between the 1900-1949 and 1950-1969 periods and reductions in range have been steady since. In comparison, declines in Northland, Southland, West Coast and Tasman/Nelson appear to be more recent and greatest between the 1970-1989 and post-1990 periods. The apparent shrinkage in range is supported by numerous observations in the literature. Australasian bittern distribution is now biased towards coastal areas and lowland wetlands of the North Island. Information indicates that range reductions were paralleled by marked declines in numbers: 34% of pre-1900 records were >1 bittern and 7.3% were >10, whereas post-1990, only 19% of records were >1 and 0.7% >10. The clearance and drainage of wetlands (c. 90% loss) and shooting were major causes of declines, but contemporary threats include continued habitat loss and degradation, accidental deaths from a range of causes, and predation by introduced mammals. Current trends in Australasian bittern populations suggest that they should be reclassified as Nationally Critical under the New Zealand threat classification system. Conservation management should focus on restoration of hydrology, water quality and aquatic food supplies, predator control, reedbed management and maintaining regional wetland networks. © The Ornithological Society of New Zealand Inc.


O'Donnell C.F.J.,Science and Policy Group | Pryde M.A.,Science and Policy Group | van Dam-Bates P.,Science and Policy Group | Elliott G.P.,Science and Policy Group
Biological Conservation | Year: 2017

Invasive mammalian predators pose one of the greatest threats to biodiversity globally, particularly on oceanic islands. However, little is known about the impacts of these invasive predators on bats (Chiroptera), one of the most specious mammal groups, and one of the most widespread groups of mammals threatened on oceanic islands (> 200 spp.). Nearly 50% of the world's threatened bats are island endemics and because they are often the only native mammals on islands, they fulfil important ecological roles such as pollination and seed dispersal. Long-tailed bats (Chalinolobus tuberculatus) are critically endangered because of predation by exotic mammals, particularly ship rats (Rattus rattus), introduced by humans to the island archipelago of New Zealand. We monitored the survival of bats in three colonies in temperate rainforest in Fiordland over 22 years. Since 2009, we controlled predators during irruption phases and compared survival of bats in previously untreated areas with survival in forest blocks treated using rodenticides deployed in bait stations. Survival was estimated using multi-state mark-recapture models in Program Mark 7.0 with > 15,000 bats tagged. Survival was primarily dependent on year and age of bats, although seedfall intensity of the dominant canopy tree and predator management was also influential. Survival in long-tailed bats was as high as, or higher, than figures for bats generally in years with low predator numbers or predator control. Survival was markedly higher in treatment years when predators were managed (0.82 compared to 0.55). Population modelling indicated managed colonies will increase (λ > 1.05) whereas unmanaged colonies will decline (λ = 0.89 − 0.98) under scenarios that reflect increased frequency of beech mast and predator irruptions. Thus, effective predator control is essential for recovering long-tailed bat populations. Warming temperatures indicate that predator irruptions are becoming more frequent, which would require more predator control in the future than at present if declines in bat populations are to be reversed. These results are relevant to the conservation of threatened bats on oceanic islands, given the abundance of exotic mammalian predators, particularly ship rats, on them. © 2017


Towns D.R.,Science and Policy Group | Towns D.R.,Auckland University of Technology | Borrelle S.B.,Auckland University of Technology | Thoresen J.,Auckland University of Technology | And 2 more authors.
New Zealand Journal of Ecology | Year: 2016

The progressive removal of invasive mammals from the Mercury Islands has led to over 25 years of field study designed to test the processes of restoration and natural recovery of these seabird-driven island ecosystems. Resulting from this work, four key restoration questions can now be identified as fundamental to designing island restoration programmes. The questions are: what is the regional context of the island (biogeography); how does each island ecosystem operate (ecosystem function); how have invasive species changed the ecosystem (response effects); and how can progress towards a restoration goal be defined (outcome measures)? Examples of how these questions influenced restoration in the Mercury Islands are provided with Korapuki Island as a case study. However, unpredicted and subtle responses can eventuate. In the Mercury Islands these included a hitherto unknown honeydew parasite-bird-gecko food web and subtle effects of rats on plant regeneration. Promising outcome measures of restoration progress are now being developed, including indices of marine influence using stable isotopes of nitrogen and the use of network analysis to analyse the composition of invertebrate food webs. © New Zealand Ecological Society.


Crowell M.,Science and Policy Group | Martini M.,Hokitika Office | Moltchanova E.,University of Canterbury
New Zealand Journal of Ecology | Year: 2016

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. We compared the proportional reduction in possum and rat population indices between standard aerial 1080 treatment, primary repellent treatment (0.17% wt/wt d-pulegone in prefeed and 1080 baits), and combined repellent treatment (0.17% wt/wt d-pulegone and 0.10% wt/wt anthraquinone in prefeed and 0.17% wt/wt d-pulegone in 1080 baits). All three treatments reduced the post-operational tracking rate of relative abundance for rats compared with the pre-operational rate. The standard treatment (100% proportional reduction in both blocks) was more effective than either repellent treatment, although the small difference between standard and primary (100% and 96% proportional reduction in two blocks) may not be meaningful, given the coarseness of the rat tracking index. The combined repellent treatment was the least effective (78% and 89% proportional reduction in the two blocks), with post-operational tracking indices of 3% ± 2 (standard error) and 8% ± 6. There was no difference in the three-night Bite Mark Index for possums between treatments. The results indicate that both repellent treatments could be used for possum control; however, the combined repellent treatment did not control rats to <5% tracking index, a level considered sufficient to protect native animals from rat predation. The primary repellent treatment reduced both possum and rat population indices satisfactorily, indicating it could be a useful bird repellent candidate if d-pulegone can be stabilised in cereal baits. © New Zealand Ecological Society.


Russell J.C.,University of Auckland | Broome K.G.,Science and Policy Group
New Zealand Journal of Ecology | Year: 2016

New Zealand has just passed half a century of rodent eradications on islands. Confirmation of the first rat eradication in New Zealand on Maria Island/Ruapuke coincided with the devastating rat invasion on Big South Cape Island/Taukihepa. We review the early history of rodent management in New Zealand leading up to and including the Big South Cape Island/Taukihepa ship rat invasion, and document the development and implementation of rodent eradication technologies on New Zealand islands up to the present day. In the last decade major advances have been made in multi-species eradications including rodents, community engagement, mouse eradication, transferring techniques to mainland eco-sanctuaries, and developing new tools for rodent management. The challenge of rodent biosecurity to prevent reinvasion which loomed large only a decade ago, is now being addressed through a combination of research and robust management procedures. Increased emphasis is now being placed on documenting species and ecosystem recoveries following rodent eradication. We identify the major challenges to further expansion of rodent eradication throughout New Zealand as working with multiple stakeholders on inhabited islands, efficiencies of scale on very large islands, and the implementation of cost-effective barrier technologies on the New Zealand ‘mainland’. © New Zealand Ecological Society.


Cowan P.,Landcare Research | Booth L.,Landcare Research | Crowell M.,Science and Policy Group
New Zealand Journal of Ecology | Year: 2016

Concern about non-target risks to native birds, particularly kea (Nestor notabilis), from aerial poisoning has prompted the evaluation of potential repellent compounds that could be incorporated into the cereal pellet bait used for possum (Trichosurus vulpecula) and rat (Rattus spp.) control. Initial trials of d-pulegone and anthraquinone were not wholly successful, with the former having poor stability in bait and the latter reducing bait uptake by rats. While research to stabilise d-pulegone in bait remains an option, a review of alternative compounds was undertaken to assist with decision-making about future directions for research, including consideration of possible formulation issues and cost. Most of the information reviewed related to use of repellents for crop protection where the aim is to reduce economic loss rather than prevent feeding on the crop, whereas preventing feeding is the primary aim for native bird protection. A further constraint was the lack of information for many compounds on response of rodents and possums. Cinnamamide, tannic acid, caffeine, garlic oil, ortho-aminoacetophenone, and thiram were identified as possible candidates and evaluated in relation to their potential to repel native birds from eating cereal baits without affecting efficacy for possums and rats. Cinnamamide, caffeine, and thiram, while effective as bird repellents, are likely to be repellent to rats at concentrations suitable for use with native birds, including kea. The little information found suggested that garlic oil was repellent to birds; it has not been formally tested on possums and rats, but anecdotal evidence did not suggest strong aversion. Ortho-aminoacetophenone appears effective as a bird repellent, but its repellency for possums and rats requires clarification. Tannic acid has some efficacy as a bird repellent, and is not repellent to possums and rats at lower concentrations. It is not clear if tannic acid exerts its effect solely as a primary repellent or whether it also has secondary repellent effects. In order from most to least promising, tannic acid, ortho-aminoacetophenone, and garlic oil are worthy of further investigation. Because each compound has demonstrated some efficacy as a bird repellent, initial testing should focus on screening against possums and rats. © New Zealand Ecological Society.


PubMed | Landcare Research, Science and Policy Group and 22 Forres Street
Type: | Journal: PhytoKeys | Year: 2017

A new species of the New Zealand endemic grass

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