Board Meeting:
March 2012
Agenda Number:
13 (iv)
File Reference:
L
H
I
B
Item:
Environmental consequences of the impacts of the continuing use of Talon
®
, other brodifacoum based baits, and other second generation anticoagulant rodenticides (SGARs) by Lord Howe Island residents and the Lord Howe Island Board as part of a rodent control programme on Lord Howe Island.
Background:
The Lord Howe Island Board is currently supporting the development of a plan to eradicate rodents from Lord Howe Island. The toxin that has been proposed for use in the operation is brodifacoum, a second generation anticoagulant rodenticide, which has been effective in over 200 eradications worldwide.
During the 2001 eradication feasibility study, the consultants noted the use of the brodifacoum based Talon
® rodenticide in the control program at the Board’s nursery, and by residents to control mice around their properties. They noted that ongoing use of brodifacoum was ill advised given environmental impacts associated with prolonged use, and the risks of the development of resistance or bait avoidances that might compromise a future eradication.
Evidence of environmental impacts associated with brodifacoum use in rodent control on LHI have recently been noted with positive lab tests being returned for masked owls, buff banded rail and the Lord Howe Woodhen. The continued unmitigated use of brodifacoum or other
SGAR products will inevitably result in further impacts on island fauna.
Current Position:
Brodifacoum based rodenticides are currently used at the Board’s nursery, Waste
Management Facility, tourist establishments and by island residents. Island residents are able to purchase Talon
®
locally or import other brodifacoum products.
Recent lab tests have shown that brodifacoum is entering the environment and poisoning native species, including woodhen as a result of the current rodent control programme. The ongoing use of brodifacoum based rodenticides increases the potential for development of resistance which would undermine an eradication attempt. Alternative rodent control measures need to be considered to prevent the potential for resistance and off target impacts to wildlife. Eradication will eliminate this ongoing impact.
Impacts of current control on non-native fauna:
Recent lab testing has shown that the ongoing use of brodifacoum based rodenticides on
LHI is resulting in the toxin entering the environment. In December 2009 a radio tagged
Masked Owl was found showing signs of poisoning. The animal was administered vitamin K and recovered. Since then the LHIB have been collecting dead wildlife that are considered vulnerable to primary or secondary poisoning to test whether brodifacoum is entering the environment.
Liver samples of 2 Masked Owl, 1 Buff-banded Rail and 10 woodhen collected between
2009 and 2011 were tested in the laboratory and 8 Woodhen (80%), 2 Masked Owl (100%)

and 1 Buff-banded Rail (100%) tested positive for brodifacoum (See Table 1). All liver samples were dissected by Island resident Courtney Turner as part of her LHIB scholarship, and samples were tested at a NSW Department of Primary Industry’s analytical laboratory.
The sensitivity of the testing used at the laboratory was to 1 part per billion or 0.001mg/kg.
This value, the Minimum Detectable Level (or MDL), is consistent with that used in other studies that have been conducted on tissue samples collected from fauna and tested for brodifacoum residues during the monitoring of non-target impacts after eradication operations.
Table 1.
Toxicology results from liver samples of LHI birds.
Species
Sampl e #
Location Collected by
Mass of sampl e (g)
Masked Owl
Masked Owl
Masked Owl
Woodhen
1
2
3
4
Prodive Boat shed
Nth Bay – in
Lagoon
Somerset
Resort
Lord Howe
Island
LHIB
Chad Wilson
LHIB
LHIB
1.906
NIL
1.199
0.392
Brodifacou m mg/kg
0.004
NIL
0.044
0.017
Above
MDL
YES
NIL
YES
YES
Woodhen
Woodhen
Woodhen
Woodhen
Woodhen
Woodhen
Woodhen
Buff banded rail
Woodhen
Woodhen
5
6
7
8
9
10
11
12
13
14
Waimarie
Lord Howe
Island
Lord Howe
Island
Lord Howe
Island
Lord Howe
Island
Lord Howe
Island
Lord Howe
Island
Opposite
GWMH
Lord Howe
Island
Lord Howe
Island
NB: NIL data returned for sample 2.
LHIB
LHIB
Rodney
Thompson
Judy Shick
LHIB
LHIB
LHIB
LHIB
LHIB
LHIB
3.108
7.185
3.684
6.483
1.707
8.559
5.206
0.845
1.574
3.327
0.004
<0.001
0.13
0.001
<0.001
0.012
0.001
0.019
0.062
0.016
YES
NO
YES
YES
NO
YES
YES
YES
YES
YES

Photo 1: Image of deceased Woodhen (sample # 7) displaying typical symptoms of rodenticide poisoning. The bird was delivered to LHIB by Rodney Thompson on 7/04/2010. The bird was unable to walk and was bleeding from nostrils, beak & vent and subsequently died.
While it can ’t be confirmed that brodifacoum poisoning was the cause of death in these animals, it can be confirmed that the current patterns of brodifacoum use for rodent control do result in the toxin entering the natural environment on LHI. There is no reason to suspect that poison has not been entering the environment over the past decades, or that it will not continue to do so into the future if brodifacoum remains in use.
A key concern raised by the community during exhibition of the Rodent Eradication Strategy was the impact of non-target mortality associated with the use of the toxin and the toxin entering the environment. These results show that toxin is entering the environment and entering native species. While it is possible to offset non-target mortalities against the significant environmental benefits resulting from an eradication, the same can not be said in the case of ongoing control operations where such impacts are sustained, and unmanaged.
The future of rodent control on LHI:
The issues of brodifacoum resistance and the toxin entering the environment highlight the need to reconsider the use of brodifacoum or any other second generation anticoagulant rodenticide products on LHI for the ongoing control of rodents.
Given the resistance among mice to Warfarin, and potentially other first generation anticoagulant rodenticides (FGARs) such an action is likely to result in increased mouse activity with associated impacts to residents and the environment, and damage at the nursery. While it is possible to use (according to manufacturers instructions) several FGAR products including RAMIK
®
(containing Diphacinone) and RACUMIN
®
(containing

Coumatatralyl) on a rotational basis to combat rodent activity, this is unlikely to be as effective as at present, and kill traps could be used in addition to toxins both at the nursery and within resident ’s dwellings. This will require a commitment for the disposal of dead rodents by the board and residents.
In light of the range of toxins currently available for use as rodent control agents it seems probable that in the absence of SGARs, effective control would be more difficult to achieve in the settlement area with toxins alone. There would likely be increased community disquiet, and possibly negative perceptions among tourists if rodent activity increases.
Notwithstanding these issues, SGARs should be avoided to minimise the environmental impacts of a rodent control programme, and given that it is possible to eradicate rodents on
LHI this should always be considered the preferred option.
Options for future control:
1. Maintain the current control system utilising SGARs. The ongoing use of SGARs would result in non-target impacts and increase the potential for the development of SGAR resistance that would render future control or eradication ineffective. Such an approach would also fail to halt further environmental degradation, undermining the Island’s World
Heritage values which underpin the Island’s tourism industry. It is also arguable that such an approach would be in conflict with the Boards charter under section 5(1)(e) and
(h) of the LHI Act that states: to manage, protect, restore, enhance and conserve the Island’s environment in a manner that is consistent with and promotes the principles of ecologically sustainable development set out in section 6 (2) of the Protection of the Environment Administration Act 1991 ; and to have regard to the long term and cumulative effects of its decisions.
2. Conduct control in the settlement only using FGARs. This may result in increased levels of rodent activity (particularly mice) but reduced impacts of rodenticides. Such an approach would fail to halt further environmental degradation, u ndermining the Island’s
World Heritage values, and thus the Island’s tourism industry. It would also require either a voluntary agreement among the community to stop using SGARs, or for the Board to investigate legal mechanisms to prevent the possession, import, sale and use of SGARs.
As a first step the Board should develop and implement a policy to cease use of SGARs in all Board operations.
Options 1 and 2 would need to supplement poisoning with active trapping by the Board and residents. This would increase the efficacy of control with both SGARs and FGARs, but would be particularly important if FGARs were used as the primary poison for use in control. Given the significant commitment required by both the board and community for such an ‘active’ control programme, it is unlikely to be sustainable in the long term.
Consequently, such an approach is best suited to a defined period of control leading up to an eradication which would eliminate the need for control.
 At the nursery, and potentially at tourism lodges auto-reset rodent kill traps such as ‘Ekomille’ could be utilised that would enable multiple captures before the need to empty the trap. These devices cost approximately $1000, and the company have offered the Board the opportunity to trial the device prior to purchase.
3. Complete planning and implementation of an eradication program as described in the
Draft Eradication Plan.

Recommendations:
1. Inform the LHI community of the recent findings of brodifacoum poisoning of woodhens that has resulted from the current use of this toxin to control rodents, and that such impacts will continue with ongoing use of the toxin.
2. Encourage the community to only use FGARs, supplied by the Board and to supplement control by the use of traps.
3. Investigate options to prohibit the use of SGARs in the lead up to an eradication program.
4. Continue to inform the community that in contrast to control, brodifacoum can be used effectively within an eradication programme given the short time period of action, ability to mitigate risks to at-risk species, and that any non-target losses are rapidly offset by the significant biodiversity gains delivered by removing the competitive and predative effects of rodents in the environment.
Prepared By: David Kelly Manager Environment & Community Development
Approved By: Stephen Wills Chief Executive Officer