Plastic problem in conservation chewed over in research project

Recently published in the March edition of Forest & Bird, Pitt's study not only highlights the extent of the problem but also proposes practical solutions.

While New Zealand has banned single-use items, like plastic straws and cutlery, and removed more than two billion plastic bags from circulation since 2021, the conservation sector lags behind in reducing plastic usage.

Every year, over 96,000 single-use plastic chew cards are purchased and used to monitor mammalian pest species by collecting tooth mark impressions, ­­­­­potentially increasing microplastic in landfills and the environment. At 5g each, that’s a substantial 480kg of corflute plastic, eventually placed into at-risk ecosystems.

Pitt's research, conducted as part of her PhD, initially brought attention to this issue by estimating the amount of microplastic left behind after monitoring operations. Trials conducted across various habitats in New Zealand revealed approximately 15% of the plastic deployed ends up as microplastic residue. That’s 72kg left as waste and 408kg sent to landfill.

So what are the alternatives?

The second stage of Pitt's research identified a promising alternative to plastic chew cards, made of recycled wood pulp. 

"Preliminary findings indicate that pest mammals, including possums, rodents, and hedgehogs, exhibit similar interaction rates with both plastic and wood-pulp cards, with bite marks being equally identifiable on both materials," Pitt shares.

The study found these wood-pulp cards are not only more cost-effective but also environmentally sustainable, as they biodegrade without causing harm. 

"Often plastic tracking tunnels or wax tags are used in conjunction with the chew cards, and so sustainable plastic-free tunnels are also in the pipeline to provide another long-term alternative," Pitt added.

The final stage of her research involved a social survey targeting key stakeholders in the New Zealand Conservation sector. The aim was to understand the views of integrating sustainable pest mammal monitoring tools into their operations.

"Respondents to the survey identified that the most important aspect of any new pest mammal monitoring tool is its effectiveness, accuracy and cost," Pitt says. "An overwhelming number of respondents agreed that shifting towards sustainable options was an optimum next step for the conservation sector if the tools work as well as the traditional ones."

The research done in Pitt's PhD highlights important steps the NZ conservation sector needs to take to be more proactive in reducing plastic reliance and the amount of microplastic residue being left in our most at-risk ecosystems. With promising feedback, it’s an exciting time to see how Pitt’s practical suggestions and alternatives will be received, fostering a more sustainable sector.

There has been an increase in environmentally friendly practices in many New Zealand conservation operations, such as limiting the spread of track cutting and research into toxin use. Conservation initiatives with short-term negative impacts and longer-term benefits have benefitted from studies to make them more sustainable.

The Predator Free 2050 movement currently comprises over 5,000 groups, 13 landscape partnerships, and three iwi. By introducing these initiatives to smaller groups first, perceived risks and outcomes may be identified and resolved, leading to use by larger groups. This research is ongoing.