The study was conducted by Te Herenga Waka-Victoria University of Wellington with results published in the New Zealand Journal of Ecology and the international journal, Conservation Biology. It tracked the populations of 12 bird species in Remutaka and Aorangi before, during, and after three aerial 1080 operations were used for predator control in the area over a 10-year period. The results showed there was an overall positive response of native bird species’ populations when pest mammals were controlled by aerial 1080.
Parallel monitoring of native beetles and wētā also found no negative effects of aerial 1080, and instead showed that when rodent populations were reduced the abundance of beetles and wētā increased.
Te Herenga Waka’s Stephen Hartley, an associate professor at the University’s School of Biological Sciences, is one of the researchers and authors of the study. He says the motivation for the study was to see what the principal causes of changes in bird populations were - in the context of mammalian predators (rodents, stoats and possums), mast years and aerial operations.
"It was Dr Olivia Vergara’s PhD that examined the responses of the insects in the area, and Dr Nyree Fea who demonstrated the positive response of native bird species’ populations when pest mammals are controlled."
"Mast years, when trees produce abundant fruit and seed, benefit many forest birds, but only if pests are simultaneously controlled. This is something that can only currently be achieved effectively and at scale with aerial 1080."
Dr Hartley says the wider study has been a significant undertaking, involving committed teams of research assistants visiting seven sites on six occasions every year for ten years. The data collected, forming the basis of three MSc and two PhD students’ theses. OSPRI’s Research Manager, Richard Curtis, says the study proved that 1080 was an effective tool for pest control and had a positive impact on native bird populations and insects. "We found that the forests did not "fall silent" following the use of 1080, on three separate occasions. The significance of this study is its duration and the consistency of the findings over 10 years." The research was commissioned by OSPRI with the intention of looking into the effects of 1080 on the forest ecosystem, including birds and insects.
Dr Curtis says the results of these studies are ‘reassuring’, demonstrating that 1080 can be used to control pests without harming native birds.
"While our long-term research programmes continue to look for alternatives to 1080, with technology playing an ever-greater role in pest control, these studies show that 1080 is an effective tool for pest control, with flow-on benefits for native fauna. For now, it remains the only effective pest control option at scale, helping to eradicate TB from possums across millions of hectares of remote bush around the country. Moreover, as its use becomes ever more refined, it is important to continue to monitor the impact of 1080 on all mammalian predators and native biodiversity."
Image courtesy of Jonathan Astin.