1. Using less 1080 in aerial baiting Graham Nugent, Grant Morriss Landcare Research, P.O. Box 40, Lincoln 7640 Operational research funded by Animal Health Board and Department of Conservation

2. Overview Completed trials: Landsborough Isolated Hill Whanganui Further bucket development Current trials Cascade Maruia

5. Landsborough Results Std 3kg/ha broadcast with no prefeed alignment Clustered 0.25 kg/ha with prefeed alignment Clustered 0.25 kg/ha with no prefeed alignment Similar possum kills with broadcast and cluster + aligned prefeed. Similar possum kills achieved with 92% less toxic bait. Indicates the amount of 1080 needed can be greatly reduced, but further replication is required.

6. Isolated Hill Results

7. Reduction in possum activity in relation to rat activity levels Suggests high rat numbers reduces possum kill with low sowing rates

8. Conclusions 250 g/ha 1080 bait achieved poorer kills compared to 3 kg/ha. –Possum and rat numbers were moderate At 30-40 baits per ha there was evidence of a negative rat effect –Implies competition for bait even though < 10 rats /ha –Implies caching (?) At 400-500 baits/ha there was no rat effect –Overbaiting eliminates competition for bait (?)

9. Whanganui National Park

10. Wanganui Trial Design Area divided into 10 blocks (600-1000 ha each): 4 treated with broadcast sowing Broadcast prefeed with 1.00kg/ha of 6g non toxic baits Broadcast toxic with 2.00kg/ha of 12g 1080 baits 2 treated same as Isolated Hill Strip-sown prefeed with 0.50kg/ha of 2g non toxic baits Cluster-sown toxic with 0.25kg/ha of 6g 1080 baits. 2 strip-sown with swaths 130 m apart Strip-sown prefeed with 0.60kg/ha of 2g non toxic baits Strip-sown toxic with 0.60kg/ha of 6g non toxic baits 2 strip sown with swaths 180 m apart Strip-sown prefeed with 0.45kg/ha of 2g non toxic baits Strip-sown toxic with 0.45kg/ha of 6g non toxic baits

13. Results: Cluster sowing

14. Results: Strip sowing

15. Discussion Outcomes not linked to pre-poison possum abundance (highest numbers at Wanganui where there was best result) –Indication that rat abundance negatively affected cluster kill at Isolated Hill, but not at Wanganui even though there were as many rats at Wanganui. –Isolated Hill and Wanganui differed in time between pre-feed and toxin – 12 days vs 7 days. New hypothesis: Assuming bait type not crucial, long interval between pre-feed and toxin means changes in where possums are foraging will have dissipated, so possums take a long time to find clusters, giving rats time to find and cache all or most of the bait.

16. New bucket development Lightweight -able to be used by smaller choppers GPS control of bait release -caters for varying speed of chopper -potentially greater accuracy in bait placement

17. Ground- truthing 40 – 60 knots 50 or 100 m above ground Cluster size -12 x 8m Throw forward - 33-76m

18. Cascade trial blocks Testing: -timing between prefeed & toxic -flightline spacing

20. Maruia trial blocks Testing: -rat interference -timing between prefeed & toxic -flightline spacing

21. Discussion Cluster sowing at 250g/ha and 100m flight path spacing has matched or bettered possum kills achieved with 2000-3000g/ha broadcast at 100-240m flight path spacing in two of three trials. > 90% reduction in toxin use & > 70% reduction in direct costs (flying & bait). Current trials may increase reliability (i.e. prefeed timing). New concept (simultaneous prefeed/toxin) may halve flying costs. Potential for more refinement & savings.

22. Acknowledgements Thanks to: AHB DOC Amuri Helicopters, HeliOtago, Beck Helicopters Tracmap Bushworks Contractors Vector Control Services