Predafiles: how to solve the problem of pest mammals in NZ

Photo: nerissa’s ring via Flickr, CC-BY.

Pest mammal control, in particular the use of 1080, has long been a hot topic in New Zealand. Feratox owner, Jeremy Kerr did an excellent job of reigniting the 1080 debate last year when he threatened to contaminate baby powder with the toxin. The media storm that followed highlighted the polarising nature of this ongoing debate. While there is strong opposition to the use of 1080 as a large scale, aerially applied control tool, much of this opposition appears to be based on misconceptions. Although scientists and the general public may disagree on it’s ongoing current use, I think we can all agree that 1080 isn’t without its flaws and a search for alternative control methods is necessary.

Many current control methods, such as trapping, are impractical for large-scale control. Photo: Amanda Black.

Due to the multi-faceted nature of the pest mammal problem in New Zealand, there are a lot of different interested parties helping to fund research around the country. But is too much of this research focused around small-scale control? Blackie et al. discuss the latest innovations in long-term mammalian pest control, including the toxins PAPP (para-aminopropiophenone) & SN (sodium nitrate) in their paper (found here). One of things I find most exciting about PAPP & SN is their mode of action. Both of these toxins reduce the oxygen carrying capacity of red blood cells with affected animals becoming lethargic and falling asleep before dying, with no signs of suffering. This is a drastic improvement on previous toxins, including 1080, where animals may endure prolonged suffering. My concern with these compounds, however, is that while they may provide a “long-term” solution on a small scale, large-scale application on the mainland is impractical. This is due to the inability to protect non-targets using aerial application, the only feasible large-scale approach, for the foreseeable future, given New Zealand’s rugged landscape.

So, what other options are there? For well over a decade now, scientists in New Zealand have been working on an immunocontraceptive for possum control. Internationally, similar research has been taking place on other pest mammals, such as grey squirrels and wild boar. These contraceptives offer a humane alternative to toxins but also present a number of other complex issues. For example, they need to be species specific to prevent non-target effects, this means a different immunocontraceptive would need to me developed for each separate pest mammal species in New Zealand. Hopefully with research ongoing around the world, the process of developing new contraceptives will become faster and less expensive and this will become less of an issue.

A suitable mode of delivery also needs to be found and there are some concerns that individuals with a weak immune response may be selected for, resulting in reduced efficiency over time. There is also a potential moral dilemma; everything an animal does is driven by it’s built-in drive to survive and reproduce, is taking away an animals ability to reproduce therefore any better from an animal welfare point of view?

Pest mammals threaten many of our iconic bird species. Photo: Amanda Black.

Based on a study conducted by Roger Wilkinson at Landcare Research, the general public accept that possums at least are a major threat to NZ forests and the agricultural industry. Opposition to 1080 and other toxins can therefore be assumed to be based on perceived non-target effects, or the welfare of the target animals as opposed to a a belief that control is unnecessary. When asked about whether various control methods were acceptable or not, only 14% of respondents believed that 1080 control was “very acceptable”, compared to 57% when it came to interfering with fertilisation. Respondents considered immunocontraceptive methods to be more humane in general than other control methods. These results are encouraging in that should an effective contraceptive become available, public acceptance should be greater than it has been with other control strategies. Increasing public awareness about such alternatives to toxins and kill-traps may help attract more funding to these areas of research.

Collaboration between the general public, conservationists and industry is imperative to finding and implementing the best available solutions to our shared problem and to the ongoing improvement of these solutions. If 1080 is not a solution people are comfortable with, those opposed should be proactive and strive to support research into alternative solutions or get behind community initiatives to monitor trapping lines for example to help minimise its use. In an environment like we have here in New Zealand where doing nothing is not an option, simply protesting a particular method of control isn’t going to help anyone, least of all our native wildlife.

The author Mandy Black is an undergraduate student in the Bachelor of Science with Honours taught at Lincoln University. She wrote this article as part of her assessment for ECOL 608 Research Methods in Ecology.

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