In June 2017, Zero Invasive Predators Ltd (ZIP) began a trial within 2,500 hectares at the confluence of the Jackson and Arawhata Rivers, South Westland, to test whether a modified technique for applying aerial 1080 could completely remove possums, and potentially rats (i.e. not just suppress them to low numbers). Two applications of non-toxic prefeed bait were flown in June, and the 1080 bait was aerially applied on 5 July. Pre-operational monitoring indicated that possums were at 50%, while rat numbers were low.
Since then, a core area of 400 hectares within the treatment zone has been intensively searched for any surviving possums and rats using chew cards, tracking tunnels and cameras.
By Friday 25 August, 52 days (and over 77,000 'detection nights') after the application of 1080, we had not recorded sign of any surviving possums, or rats! We therefore concluded that our modified technique for applying aerial 1080 is very likely to have successfully completely removed possums and rats at this site.
Consequently, we have decided that there is no need for a second application of aerial 1080 for the purposes of this trial (we had applied prefeed on the 3rd August in case a second application was needed to target any surviving possums or rats). This trial is now complete.
We have subsequently initiated a second trial at the site, simulating a ship rat incursion into a rat-free area, to determine the spread of a first generation of ship rats (i.e. the Gen One 'footprint') across a forested landscape. The results will help inform the design of tools and techniques to respond to a rat incursion in a timely manner. This project may require the targeted use of aerial 1080 as a ‘spot treatment’ to remove these individual rats.