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| JANUARY 2010 | ISSUE 1 | |
ISI News Issue 1, January 2010
In this issue:
Editorial
Welcome to the first edition of ISI News.
As the range of projects that Invasive Species International (ISI) is involved in and the scope of our services increases, we felt it would be useful to provide a regular up-date on our activities for our partners, clients and colleagues.
In this first edition I thought I’d briefly background the establishment of ISI and the services we provide.
New Zealand has a long history of invasive species management and has achieved some notable biodiversity conservation and biosecurity successes. Landcare Research staff have been involved in many of those projects. Increasingly our people are being called upon to provide technical advice and research services in support of invasive species research and management activities around the world. Growing international interest in addressing the threats that invasive plants and animals pose to indigenous biodiversity and people’s livelihoods led Landcare Research to establish ISI in 2008.
We have identified a pressing need for authoritative advice in selecting, designing and planning invasive species management projects, for providing supporting research, and in independently evaluating the progress and outcomes of projects.
An important element of our approach is that we team up, where appropriate, with people and organisations with complementary expertise. Here at Landcare Research we have access to more than 300 scientists with a wide range of skills and experience, and we have extensive networks of contacts here in New Zealand and abroad. We also look to build capacity in client organisations to ensure invasive species management outcomes may be sustained.
That’s enough about us and how we came about. Please go to our website if you would like further information. I hope you find this newsletter interesting and I look forward to sharing views on invasive species work in future columns. Your feedback and suggestions would be most welcome!
Best wishes,
Alan Saunders
Manager – Invasive Species International
Programme review – red foxes in Tasmania
Red fox
Invasive species eradication programmes can be expensive and the consequences of failure can be dire. How does an organisation know if its eradication work has been successful or is on-track? Increasingly ISI staff are being commissioned to undertake independent programme reviews, including a review of European red fox (Vulpes vulpes) eradication efforts in Tasmania, Australia.
In 1999 foxes, which are common on the Australian mainland, were reported to have spread to Tasmania. Predictions that foxes could put 78 of Tasmania’s native vertebrate species at risk led the Tasmanian Government to establish a taskforce to attempt to eradicate the animals.
The problems faced by the taskforce are daunting. Foxes are not easily detected. There are few animals, the area of the incursion is unclear, and public reports have proved unreliable as many turn out to be of other species. In recent years foxes have been detected with certainty by searching for faecal scats and testing them for fox DNA. This has shown that low numbers of foxes are present over at least half of the island.
The only effective control method is buried baits containing the toxin 1080. The non-target impacts have been assessed as biologically acceptable, but the method is unsuitable in urban and peri-urban areas where foxes are known to be present but where pet animals would be at risk. Baiting is conducted currently over about 600 000 ha of rural land every year in Tasmania. This has not killed all foxes potentially exposed as new faecal scats continue to be found in areas previously baited, and it does not provide direct evidence of success as victims are not locatable.
ISI invasive species ecologists, John Parkes and Dean Anderson were commissioned to review progress up to 2009 and to provide a fresh view of whether eradication was achievable within a realistic timeframe and budget.
“The key finding of our review 
was that the processes used to locate foxes and those used to kill them were not integrated. There are time lags in validating reports of fox sightings or DNA in scats and in organising responses. There is uncertainty about the behaviour of foxes during these delays” says John.
“We provided recommendations to maximise the prospect of foxes being exposed to the toxin, and approaches for post-control monitoring and prompt reaction for further control when surviving foxes were detected. Our report also suggested there is a need to develop new control methods to put these survivors at risk (perhaps they will never eat the baits) and to deal with urban foxes.
“Finally we provided advice and a model to help ensure that ‘no detections equals no foxes’. The model incorporates expert opinion and field data to identify high priority areas for surveillance, quantify the probability of local extirpation following control, and provide a broad scale probability of eradication for Tasmania.
“Given the programme managers continue to learn and adapt, we concluded that eradication was still possible.”
Feasibility study & planning - eradicating North American beavers from southern Patagonia
North American beaver
A reminder of the importance of social, political and economic dimensions to eradications comes from a proposal to eradicate invasive beavers from southern Patagonia.
Over the last 50 years beavers have colonised virtually all riverine habitats on Tierra del Fuego. Their effects as ‘ecosystem modifiers’ are plain to see; riparian forests have been cleared and streams and rivers dammed to create ponds and wetlands - with significant ‘downstream’ impacts.
More recently beavers have crossed the Straits of Magellan and have established in continental Chile, effectively magnifying the threats they pose. In response the Presidents of Chile and Argentina have signed an agreement to cooperate to address these impacts. Following an initial assessment by a team consisting of local and international specialists a John Parkes led an international team to develop a Feasibility Study. This study concluded that eradication was technically feasible - although not simple to organise given the binational coordination required, and logistically challenging and costly.
A committee has been established and progress is being made in the preparation of a bi-national eradication plan which will be used as a basis for grant applications and to guide collective decision- making.
As the ISI advisor to this committee Alan Saunders has emphasized the importance of putting an agreed plan in place. "Having agreed objectives and priorities, and a processs for making management decisions is fundamental if eradication is to be achieved,” says Alan.
"While tried-and-proven field techniques are available, the remoteness, terrain and climate of southern Patagonia, coupled with a lack of precedents for a beaver eradication on this scale makes this proposal a challenging one. Increasing cooperation between Chilean and Argentinean scientists and managers augurs well for eventual success in this project.”
Pacific biocontrol strategy workshop
Chris Winks showing the successful biocontrol agents on mistflower at Orakei
Last November a workshop was held in Auckland, New Zealand, to discuss whether biocontrol of widespread invasive species could be undertaken in a more collaborative basis in the Pacific, and to develop a regional strategic plan. Forty seven delegates, from 17 countries and territories, and organisations that represent the Pacific region, participated in the workshop.
“Biocontrol projects undertaken in the Pacific to date have demonstrated that biocontrol is a highly successful and relatively inexpensive tool for controlling pests and diseases in the Pacific,” says Lynley Hayes of Landcare Research, a member of the organising committee.
“A key outcome of the conference was agreement that biocontrol activity should be increased in the Pacific, as this is the only feasible way of dealing with many of the pests.”
Other outcomes included:
- A list of species that should be targeted for biocontrol was prepared. This was considered a ‘working list’ and will be reviewed regularly.
- Agreement that the many well-known, highly effective biocontrol agents currently available in the Pacific be shared more widely.
- Agreement to develop biocontrol agents for many more invasive plant and insect species. Some key projects have been identified and will be submitted to funders within the next 12 months.
- An independent advisory group will be set up to review biocontrol agent release applications and provide independent advice.
The workshop was made possible thanks to support from the Critical Ecosystem Partnership Fund, Hawai’i Invasive Species Council, Landcare Research, NZAID, Pacific Invasives Initiative, Pacific Invasives Learning Network, Secretariat for the Pacific Community, Secretariat for the Pacific Regional Environment Programme, USDA Forest Service, and the United States State Department.
Feature: Using anticoagulants to eradicate invasive rodents from islands – a balancing act
Gough Island
Penny Fisher, Research Leader - Pest Control Technologies, Landcare Research
The number and size of islands undergoing successful eradication of rodents (rats particularly) continues to grow with about 300 islands successfully treated over the last 30 years (Howald et al. 2007). ISI, for example, has been involved with planning eradications on islands such as Gough (South Atlantic), Kaho’olawe (Hawai’i) and Stephensons (New Zealand) over the last year or so.
Anticoagulants toxins are used for island rodent eradications mainly because their delayed onset of symptoms means that rodents don’t associate sublethal bait ingestion with immediate illness, and develop bait and/or poison shyness. This is critical to maximise the likelihood that all rodents will ingest a lethal amount of bait.
Brodifacoum has been used most often for eradications on large, remote offshore islands with inaccessible terrain and no human habitation or livestock. It is the most toxic of the anticoagulants, so rodents need to ingest only a relatively small amount of bait to get a lethal dose. Brodifacoum’s high toxicity to mammals and birds in general (insects appear less susceptible) means, however, that rodent bait containing brodifacoum is a primary poisoning hazard to non-target species that find and eat enough of it. Brodifacoum’s prolonged persistence and bioaccumulation in liver in mammals and birds that are sublethally exposed also creates a risk of secondary poisoning, especially for predators and scavengers that eat rodents or other creatures poisoned by brodifacoum (Erickson & Urban 2002), and, in some cases, insectivores that take invertebrates that have recently fed on bait (Dowding et al. 2006).
Increasingly, the islands being considered for rodent eradication have permanent human habitation, pastoral uses and/or close proximity to highly populated mainland areas. This raises the profile of and concerns about potential risks of brodifacoum use to human health and domestic animals, and of long-term environmental contamination or impacts on non-target species. These concerns are currently driving a re-examination of the risk profiles of a range of anticoagulants to support choices made by those planning island rodent eradications.
Recently interest has focussed on diphacinone, an anticoagulant with similar mode of action and delayed onset of poisoning to brodifacoum, but a reduced risk of poisoning to non-target species. Birds are less susceptible than mammals to diphacinone, so the primary hazard of diphacinone bait to them is reduced, relative to brodifacoum. The secondary poisoning risk to non-target mammals and, especially, birds is also reduced through the combination of lower toxicity of diphacinone and its much shorter persistence in liver tissue. But there’s a catch – for best efficacy as a rodenticide, diphacinone requires rodents to find and eat small amounts of bait daily for several days. For island eradications, this means that the timing, rate and frequency of bait applications need to be such that all rodents have the opportunity to consume bait over at least five consecutive days – a substantially different scenario to the single dose required with brodifacoum bait.
Diphacinone deployed in bait stations has been used to successfully eradicate rats (Donlan et al. 2003, Witmer et al. 2007), with recent eradication attempts through aerial application on two offshore islets (Mokapu and Lehua) in Hawai’i, where the minimisation of non-target risk and environmental persistence were critical considerations for local decision-makers. Successful eradication on Mokapu but not Lehua, indicates further development is needed and refinement of effective diphacinone baiting regimes for eradication will be an important step to capitalise on the reduced non-target risk offered by this anticoagulant.
The level of public concern around island eradications is reflected in responses to two recent operations. After the diphacinone operation on Lehua, and a recent eradication operation using brodifacoum on Rangitoto and Motutapu islands (close to Auckland, New Zealand), some community groups claimed that a range of non-target species found dead in the local areas were killed by the aerial application of rodenticide. Media coverage of these claims highlighted the importance of residue testing to confirm whether non-target species had been exposed to rodenticide, or died of other causes.
While taking environmental samples post-eradication and testing them for anticoagulant residues adds time and cost to an operation, it provides increased understanding of how compounds such as brodifacoum and diphacinone may be transferred (or not) through environmental pathways, including marine environments. Monitoring results from earlier eradications have provided important information for risk assessment for future eradications. For managers planning eradications on inhabited islands, failure to address the information gaps identified by community concerns around the aerial application of brodifacoum or diphacinone will mean that clear justification of the benefits of eradication will become increasingly difficult.
Landcare Research has both a research and a service role in assisting managers with Island rodent eradications:
- Current research focuses on the role of invertebrates as environmental vectors of rodenticide residues - invertebrates may feed on anticoagulant baits without apparent harm, but the residues in them may pose a significant secondary poisoning risk to insectivorous birds or mammals. The significance of this risk requires further investigation for both diphacinone and brodifacoum. Previous monitoring has shown residual concentrations of anticoagulants can be present in the livers of some apparently healthy animals and birds. Our research seeks to identify the environmental pathways that can lead to such ‘sublethal’ exposure, and whether this may have longer-term implications for the health of non-target birds and mammals.
- Our extensive experience in rodenticide risk analysis enable us to provide sound advice to managers planning Island rodent eradications.
- The Landcare Research toxicology laboratory offers a range of accredited tests for detecting low residual concentrations of brodifacoum, diphacinone and other rodenticides in a range of sample types, including animal tissue, water and soil.
Donlan, C. J., Howald, G. R., Tershy, B. R., and Croll, D. A. (2003). Evaluating alternative rodenticides for island conservation: roof rat eradication from the San Jorge Islands, Mexico. Biological Conservation 114, 29-34.
Dowding, J. E., Lovegrove, T. G., Ritchie, J., Kast, S. N., and Puckett, M. (2006). Mortality of northern New Zealand dotterels (Charadrius obscurus aquilonius) following an aerial poisoning operation. Notornis 53, 235-259.
Erickson, W. and Urban, D. Potential risks of nine rodenticides to birds and nontarget mammals: a comparative approach. -198. 2002. Washington DC 20460, USA, United States Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances.
Gale, R.W., Tanner, M., and Orazio, C.E., 2008, Determination of diphacinone in sea water, vertebrates, invertebrates, and bait pellet formulations following aerial broadcast on Mokapu Island, Molokai, Hawai’i: U.S. Geological Survey Open-File Report 2008–1285, 16 p
Howald, G., Donlan, C. J., Galvan, J. P., Russell, J. C., Parkes, J., Samaniego, A., Wang, Y., Veitch, D., Genovesi, P., Pascal, M., Saunders, A., and Tershy, B. (2007). Invasive rodent eradication on islands. Conservation Biology 21, 1258-1268.
Witmer, G. W., Boyd, F., and Hillis-Starr, Z. (2007). The successful eradication of introduced roof rats (Rattus rattus) from Buck Island using diphacinone, followed by an irruption of house mice (Mus musculus). Wildlife Research 34, 108-115.
Recent Kararehe Kino - Vertebrate Pest Research articles
Vertebrate pest research
For the past 44 years, the Orongorongo Valley Research Area, a 1200 ha forest area near Wellington, has been host to research on the interactions between introduced and native flora and fauna. Important new studies will help land managers decide where and when to control vertebrate pests. This work, including studies of the behaviour of ship rats in forests and a model that predicts where rat ‘hot spots’ will occur, was covered in issue 15 of Kararehe Kino, Landcare Research’s vertebrate pest research newsletter.
1080
The toxin 1080 has been a critical tool in the ongoing battle to reduce the impact of invasive vertebrates in New Zealand. But its use is not without controversy. Landcare Research’s work to reduce (use of 1080), refine (its application) and (ultimately) replace the toxin was the theme of issue 14 of Kararehe Kino, Landcare Research’s vertebrate pest research newsletter.
Upcoming Events
‘Island invasives; eradications and management’ conference,
University of Auckland, 8-12 February 2010 (www.cbb.org.nz/conferences.asp).
Following on from the very successful ‘Turning the Tide’ conference held in Auckland in 2001, this conference will also focus on recent advances in island eradications. In addition to a wide array of presentations, mid-conference tours have been arranged to offshore islands cleared of invasives, as well as ‘Mainland Islands’ where suites of pest mammals are being intensively controlled.
ISI staff are on the organising committee for this conference. We are keen to ensure attendees get as much as possible from their visit to New Zealand. If there is anything we can do to arrange meetings or site visits, please feel free to let us know.
