Download - Using less 1080 in aerial baiting
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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
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Overview
Completed trials:• Landsborough
• Isolated Hill
• Whanganui
Further bucket
development
Current trials• Cascade
• Maruia
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Landsborough Results
(b) Reduction in CTC activity
0% 50% 100%
Not Aligned
Cluster
Aligned
Cluster
Not Aligned
Broadcast
Reduction in CTCI
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.
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Isolated Hill Results
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Reduction in possum activity in relation to rat activity levels
• Suggests high rat numbers reduces possum kill with low sowing rates
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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 (?)
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Whanganui National Park
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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
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Results: Cluster sowing
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Results: Strip sowing
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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.
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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
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Ground- truthing
40 – 60 knots50 or 100 m above groundCluster size -12 x 8mThrow forward - 33-76m
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Cascade trial blocks
Testing:-timing between prefeed & toxic-flightline spacing
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Maruia trial blocks
Testing:-rat interference-timing between prefeed & toxic-flightline spacing
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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.
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Acknowledgements
Thanks to:
AHB
DOC
Amuri Helicopters, HeliOtago, Beck Helicopters
Tracmap
Bushworks Contractors
Vector Control Services