Post on 09-Jan-2016
description
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
Overview
Completed trials:• Landsborough
• Isolated Hill
• Whanganui
Further bucket
development
Current trials• Cascade
• Maruia
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.
Isolated Hill Results
Reduction in possum activity in relation to rat activity levels
• Suggests high rat numbers reduces possum kill with low sowing rates
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 (?)
Whanganui National Park
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
Results: Cluster sowing
Results: Strip sowing
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.
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
Ground- truthing
40 – 60 knots50 or 100 m above groundCluster size -12 x 8mThrow forward - 33-76m
Cascade trial blocks
Testing:-timing between prefeed & toxic-flightline spacing
Maruia trial blocks
Testing:-rat interference-timing between prefeed & toxic-flightline spacing
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.
Acknowledgements
Thanks to:
AHB
DOC
Amuri Helicopters, HeliOtago, Beck Helicopters
Tracmap
Bushworks Contractors
Vector Control Services