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Eradication science

Oct 2019 –
A research programme with funding from the Ministry of Business, Innovation & Employment (MBIE) Endeavour fund
New Zealand is a world-leader in controlling and, in some areas, eradicating invasive mammalian predators. Much of that innovation has been in developing and deploying devices (e.g. traps, bait delivery), but those devices can only achieve complete eradication if all individuals in the target population interact with them – and we know that some don’t.

Predator control routinely removes approximately 95% of a target population. However, New Zealand’s Predator Free 2050 initiative requires scientific breakthroughs to achieve 100% kills (i.e. eradication) of rats, mustelids and possums.

While 95% kills typically cost $20–$30/ha, 100% kills cost over $400/ha (e.g. pest eradication from Rangitoto and Motutapu Islands cost $1,200/ha). The prohibitive cost of eradicating the last 5% using current technology is a barrier to us achieving our Predator Free 2050 eradication goal.

As well as being hugely expensive to remove the last 5% in a pest population, survivors remaining in an area with plentiful resources will likely breed successfully and at close to their maximum rates, meaning that they act as a source for rapid population growth and expansion. This, in turn, means that more money has to be spent on controlling them, and so the cycle of control continues.

Through careful study of behaviours among pest populations, we will develop novel cues or combinations of cues to manipulate those behaviours, aiming to ensure that even the most trap-shy individuals can be tempted to their doom.

Programme goals

The fundamental questions that this programme is aiming to address are:

  • what makes survivor individuals survive control?
  • do they have predictable behavioural characteristics? (why, when others in a pest population take baits or enter traps, don’t some animals?)
  • how can we manipulate those behaviours using novel cues or combinations of cues to overcome survival behaviours?

In a world-first approach, we will develop new understanding of the individual intrinsic animal behaviours (‘personality’) that make some pest animals resistant to current control methods, and use this new understanding to develop novel tools to target intractable survivors quickly and efficiently.

We already know that trappability of animals at the population level can vary depending on the time of year because of the relative availability of food or because of behavioural changes associated with breeding, but how does this vary at the individual level to make some individuals avoid entering traps or taking baits?

Our research will enable land managers to achieve eradication cost-effectively, rather than the current paradigm of sustained (costly) predator control. Unlike sustained control, the environmental benefits of eradication continue in perpetuity. By negating the need for ongoing control, eradication will also dramatically reduce the need for repeated applications of toxins. We believe we can reduce the cost of eradication by at least 25%, as fewer control devices would be used, due to increased device encounter rates, and shorter time durations needed, due to increased device interaction rates.

Our collaboration with Māori and Moriori partners will ensure our research responds to their priorities – a first for predator tools research in NZ – and that any approaches that we develop are culturally relevant and appropriate for use on the whenua.

Programme highlights

Defining survivor personalities

Our first focus will be on animal behaviour; we will look to better understand survivor ‘personalities’ (i.e. characteristic behavioural traits) and how these differ from the ‘average’ individual in a population using recently-developed behavioural evaluation protocols. Understanding the drivers of survivors’ behaviour will then allow us to use specific cues to alter the attractiveness of sites/traps to exploit those motivations.

Researchers: Patrick Garvey, Kyla Johnstone, and Graham Hickling

Identification and development of cues

The extent to which a pest responds to a cue is a trade-off between the perceived risk, the value of the reward, and the traits of the individual. We will identify and develop a range of cues (singly and in combination) that deliberately alter the target’s perception of risk and reward.

Researchers: Al Glen, Patrick Garvey, and Grant Ryan (Cacophony project)

Working with mātauranga Māori on animal behaviour

We also acknowledge the deep understanding of animal behaviour in mātauranga Māori and will work with our iwi/imi and hapū partners to identify mātauranga associated with traditional trapping and luring, e.g. use of sound lures or recognition of cyclical or seasonal variations in animal behaviour.

Researchers: Mahuru Wilcox and Nikki Harcourt

Application in the field

The final part of this research will trial our novel approaches to increasing interaction rates with traps and other control devices in large-scale control/eradication programmes in collaboration with our agency and Māori partners. This will also include assessing the cost-effectiveness of our new approaches compared to business-as-usual.

Researchers: Grant Norbury, Patrick Garvey, and Al Glen

The role of AI in pest control

Artificial intelligence, including the use of image recognition to identify pest species has massive potential to help in targeted pest control. We will test the effectiveness of novel and innovative smart devices in: differentiating between target and non-target animals; automatically disarming in the presence of non-target animals; integrating detection and behavioural manipulation by first identifying the target animal, then employing an appropriate combination of sensory lures, and; learning and adapting to survivor behaviour.

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