Research


New Zealand is known for cutting edge technologies in pest control, pest eradication and species management. These are key focuses of the Poutiri Ao ō Tāne project.

To measure the effectiveness of wide-scale pest-control in a highly modified agricultural landscape, an intensive research programme has been implemented, led by Manaaki Whenua – Landcare Research and aided significantly by Hawke’s Bay Regional Council (HBRC), the Department of Conservation (DOC), local contractors and volunteers.

Using research to inform conservation decision-making is known as adaptive management and is a pivotal part of conservation throughout the world (Walters 1989).

The research undertaken has demonstrated that the trapping effort is beneficial for indigenous lizards and invertebrates as it releases them from predation pressure. Combine this result with cost analysis, it clearly shows that large-scale pest control across a mixed reserve/production landscape is both affordable and beneficial to the New Zealand environment.

The research undertaken on seabirds has not only made their reintroduction into the Maungaharuru-Tutira area feasible, it has paved the way for seabird reintroductions elsewhere in New Zealand. The combination of seabird research and additional research into refining pest control, along with the research relationships that have been built, means that Poutiri Ao ō Tāne will continue to benefit from adaptive management in the future.

Taking it further

Information derived from the Poutiri Ao ō Tāne research programme will have relevance across New Zealand. Consequently, emphasis is placed on publicising research findings through the peer reviewed science literature, ecological restoration newsletters, and the mainstream media. This will ensure that effective methods can be adopted across New Zealand and internationally.

Research from final report

Using research to inform conservation decision-making is known as adaptive management and is a pivotal part of conservation throughout the world (Walters 1989). Research within the Poutiri Ao ō Tāne framework has fallen into two main streams: pest control, which has been led by Manaaki Whenua – Landcare Research, and research into threatened species reintroductions, which has been funded by the Aotearoa Foundation initial investment and led by DOC.

Two research projects have been undertaken to facilitate and insure the success of the seabird translocations at Poutiri Ao ō Tāne. This research has advanced our knowledge of factors associated with successful seabird translocations and will be of benefit to similar initiatives in other locations. The first was undertaken by a post-graduate student from the School of Biological Sciences, Victoria University, Wellington (Hozumi et al. 2011). Their research examined the archaeological evidence of former seabird distributions, the prerequisite ecological requirements of a release site (soil type, vegetation, slope, position, and ability of birds to take off), and undertook a detailed analysis of the risks associated with seabird translocations. Key outcomes from this research were the recommendation to focus on tītī as a translocation species, the identification of the sea bird release site, and they also supported the earlier recommendation by DOC and other seabird experts on the number of birds that should be released initially and in subsequent years.

The second piece of research looked at supplementary feeding and fledgling biology of kōrure prior to their trial translocation and was undertaken by DOC staff on Whenua Hou (Codfish Island) (Leseberg et al. 2012). This research was necessary because kōrure have not been translocated before. The researchers took measurements from kōrure chicks to determine the average size the birds are at fledging. This is essential for understanding the optimal wing length and weight of chick selected for transfer. They also undertook an experiment to see whether chicks reared on an artificial seafood diet would fledge with the same success rate as birds on a natural diet. The study demonstrated that chicks could successfully fledge after having been hand-reared on the artificial diet, giving confidence that the proposed translocation could be successful.

Manaaki Whenua – Landcare Research undertook the research and monitoring which showed that predators have declined in the trapped area (as described under the Landscape Scale Pest Animal Control work stream). They also undertook outcome monitoring to evaluate whether the reduction in pest densities has had positive benefits for indigenous biodiversity. Landcare Research staff set up 15 monitoring transects in the predator trapping area and 14 transects in the adjacent monitoring area. Each monitoring transect consisted of five ink footprint tracking-tunnels for monitoring predators, five artificial cover objects for assessing lizards, and two weta houses, for measuring invertebrate responses. The monitoring was undertaken prior to and following the implementation of pest control. Strong positive responses were observed by indigenous lizards, particularly skinks, and indigenous invertebrates following the removal of predators. The skink response is remarkable, with tracks in the tracking tunnels having increased from undetectably low densities, to densities in the trapped area that are considerably higher than in the untrapped area.

Manaaki Whenua – Landcare Research have also undertaken research into the impacts of rabbit grazing on pasture biomass in the area, using paired trials of plots that (1) excluded livestock and rabbits, (2) excluded just livestock, and (3) open plots that were not exclusive. The results of this experiment showed that, at high rabbit densities, there was significantly more pasture biomass in plots that excluded rabbits, indicating a potential threshold above which the economic benefits of rabbit control will outweigh the costs (Ruscoe et al. unpubl.). This research would not have happened without the Poutiri Ao ō Tāne partnership.

Manaaki Whenua – Landcare Research are planning further research in the Poutiri Ao ō Tāne area, including a project that investigates the degree of trap shyness in feral cats. This will involve camera traps to record cat activity at traps. Manaaki Whenua – Landcare Research intend to run this trial on a Landcorp farm immediately adjacent to the current pest control programme.

Other pest control research undertaken as part of the Poutiri Ao ō Tāne programme includes a trial into baited versus unbaited traps, and research into long-life lures. If traps without bait were as effective as traps with bait, the cost of pest control would be significantly reduced by not having to apply bait. Results quickly demonstrated that traps with bait were more effective and this research was verified by this 12-month study. Long-life lures can increase the effectiveness of traps, by making them more attractive to pests for longer periods of time, and also bring down the cost of control because traps do not need to be re-baited as often. Currently a long-life lure consisting of the essence of a rat is being compared with conventional baits. A comparative analysis will be undertaken once 12 months of data have been collected.

Outcomes

Many of the research-specific outcomes have been described above. In summary, the research undertaken has demonstrated that the trapping effort is having a benefit for indigenous lizards and invertebrates, by releasing them from predation pressure. Combination of this result with the cost analysis described under the pest control work stream shows clearly that large-scale pest control across a mixed reserve/production landscape is both affordable and beneficial to the New Zealand environment. The research undertaken on seabirds has made their reintroduction into the Maungaharuru-Tutira area feasible, and also paves the way for seabird reintroductions elsewhere in New Zealand. The combination of seabird research and additional research into refining pest control, along with the research relationships that have been built, means that Poutiri Ao ō Tāne will continue to benefit from adaptive management in the future. In addition, research into the impacts of rabbits on biomass is of direct benefit to landowners and will therefore bring them closer to Poutiri Ao ō Tāne.

Information derived from the research programme will have wide applicability across New Zealand.  Consequently, emphasis will be placed on disseminating research findings through the peer-reviewed science literature, ecological restoration newsletters, and the popular media.  This will ensure that effective methods can be adopted across New Zealand, and internationally.

The next steps are to further engage with research providers including Crown Research Institutes and universities, so that the following research requirements can be addressed:

  • Continue with research that refines the effectiveness of pest control.
  • Continue monitoring the response of indigenous biodiversity to pest control.
  • Continue research that supports species translocations.
  • Establish research into the feeding patterns of translocated seabirds.
  • Monitor and compare the water quality levels between the protected and unprotected tributaries of Lake Tutira.
  • Undertake a predictive modelling exercise that integrates data from the habitat restoration, pest control, and species reintroduction work streams with the aim of determining baseline targets that need to be reached under each work stream to achieve the vision of protected catchments, viable populations of threatened species, and green corridors that are utilised by wildlife.

More information on this research can be found here.

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