The Rangitoto/Motutapu Pest Eradication
- A Progress Update
Stoat
The Department of Conservation (DOC) reports that the pest eradication programme is progressing exceptionally well. Near perfect weather conditions allowed the three aerial applications of bait targeting rodents to be completed well within the prescribed period and meant that bait quality was preserved for the necessary length of time. No rats or mice have been seen or caught since. The operation also had a much greater impact on stoats and rabbits than anticipated with no stoats trapped and only one rabbit seen and another caught since bait application.
A few surviving cats are suspected of still being on the islands but several have now been trapped and a number shot by the rabbit team. Of all the target species, hedgehogs seem to have been the great survivors with reasonable numbers still present on Motutapu. Hedgehogs are being targeted by trapping but the use of indicator dogs has proven the most productive method of locating survivors and numbers are slowly declining.
Setting a trap for cats
With the islands now free of rodents it is imperative that people travelling to the island are absolutely vigilant about checking their gear. Checks of boats, gear and equipment before departing are critical to ensure these pests are not inadvertently reintroduced. Please share this important message with other island visitors. For more information on the risks and how they can be minimised please contact Fin Buchanan at the Auckland Area Office on 09 445 9142.
DOC is very keen for bach owners to keep an eye out for any remaining pests. If a pest is seen please contact the pest eradication project manager Richard Griffiths on 09 445 9246 or 0272 491 531. If the pest can be captured such as a hedgehog, please capture it and call Richard on the number above for further instructions.
You may have noticed the sand pads at Islington Bay and traps on some of the walkways around Rangitoto. These tools are being used to detect and capture the last pests on the islands and it is imperative they are not walked on or disturbed. If you see anyone near these sites please explain their purpose and ask them to respect the warning signs. You will at some stage bump into the staff that are working on the pest eradication. They are out and about at all times of the day and night. They are all very approachable people so feel free to catch up with them to find out how the work is progressing. For more information about the project please contact Richard Griffiths on the numbers above.
Motutapu and Rangitoto Bait Drop
Operational planning for the eradication of the last seven mammalian pests from Motutapu and Rangitoto may have taken more than a year to complete, but it has paid dividends. Implementation of the first two phases of the pest eradication have gone like clockwork and the project is now well ahead of schedule.
First phase of operation
The three aerial applications of bait undertaken to target rats and mice were carried out on 19 and 20 June, 9 July and 6 August 2009. The excellent coverage achieved, coupled with near perfect weather conditions during and after each drop meant that rodents on Motutapu and Rangitoto were exposed to bait right through the harshest period of the winter, ensuring that the changes of operational success were maximised.
Second phase of operation
The second phase of the operation, which includes follow up work on rabbits, cats, stoats and hedgehogs, was instigated after the second bait drop.
Rabbits
An intensive search effort aimed at locating surviving rabbits began following the second bait drop. The four person rabbit team led by Derek Brown encountered just one live rabbit in two weeks of spotlighting, a spectacular and entirely unexpected result. "We expected the rabbit population to be knocked back by the poisoning, but never to the point of nearly removing the entire population," says Derek.
Incidentally, only one other rabbit has been seen on the islands despite further searches including several sweeps of the island with rabbit dogs. "While it is still early days, the prospects of successful rabbit eradication appear positive," reports Derek.
Stoats
Two weeks after the last application of bait, the islands' stoat and hedgehog trap network was activated. All 1,050 traps have been checked four times now with no stoats detected, providing an earlier than expected indicator that the islands' stoat population may be no longer. "If stoats had been present following bait application, they would have been very hungry and it is more than likely they would have been picked up in the first check of traps", says Kellie Mayo, leader of the stoat/hedgehog team.
Hedgehogs
Hedgehogs have been the great survivors of the suite of pest animals present on Rangitoto and Motutapu and are still present in relatively high numbers on Motutapu. "Hedgehogs have always been somewhat of an unknown quantity because they have not been targeted on this scale in this type of habitat before", says John Nielson who is using specially trained dogs to locate survivors.
Slugs and snails have proliferated in the lush pasture since stock were removed from the Motutapu, providing hedgehogs with an abundant natural food source. "This makes trapping hedgehogs particularly difficult, although we expect trapping results to improve now that stock have returned and the island dries out over summer", says Kellie Mayo.
Cats
Cats are still present on the island but several have now been trapped and a number shot by the rabbit team. "It is possible that we are now dealing with the last few individuals", says Michelle Weakley, leader of the cat team.
Michelle noted that cats seemed to thrive after the bait application because of the availability of animal carcasses. "Interestingly, some cats were eating just the muscle tissue of dead animals and may subsequently not have been at risk of secondary poisoning because brodifacoum does not concentrate in this area of the body", she says.
Rats and mice
Surveillance across the stoat/hedgehog trap grid has failed to detect any mice or rats, providing an early indication that the islands are now free of rodents, although two years of monitoring is required before success can be truly confirmed. This result highlights the importance of being absolutely vigilant when travelling to Rangitoto and Motutapu. Checks of boats, gear and equipment before departing are critical to ensure these pests are not inadvertently reintroduced.
Bait Drop on Rangitoto Island.
The third and final phase of the aerial rodent baiting operation was successfully completed on August 7, 2009. The weather again played its part, with the calm, sunny conditions and thorough planning once more resulting in a textbook operation.
The Department of Conservation, Auckland Area, applied Pestoff 20R cereal baits containing brodifacoum (0.02gm/kg) to the following areas of Conservation managed land to eradicate rodents (rats and mice) for the purpose of restoring island biodiversity.
DESCRIPTION OF THE AREA
The treatment area is described as all land above mean high water spring (MHWS) on the islands of Rangitoto and Motutapu and surrounding islets and rock stacks (see map below).
TEMPORARY CLOSURE OF RANGITOTO AND MOTUTAPU ISLANDS
Pursuant to sections 53(1)(a), 53(1)(b), 55(1)(a) and 55(1)(b), for reasons of public safety, Rangitoto Scenic Reserve and Motutapu Recreation Reserve was closed to public entry during and for seven days following each application of bait between 15 June and 31 October 2009. The campsite at Home Bay on Motutapu Island and the Motutapu Outdoor Education Camp (MOEC) was closed for the period 15 June – 31 October 2009.
METHOD OF CONTROL
Cereal baits containing the pesticide was distributed by helicopter over the islands on three separate occasions, taking up to three days per application, with each application being two or more weeks apart. Baiting began in the first period of favourable weather after 15 June 2009. The baits are cylindrical pellets, dyed green, approx 2 cm long. This pesticide is poisonous to humans and domestic animals.
Always remember:
· DO NOT touch bait
· WATCH CHILDREN at all times
· Poison baits or carcasses are DEADLY TO DOGS
Warning signs will be placed at all main entry points to Rangitoto and/or Motutapu islands.
A detailed map of the treatment areas may be viewed at the Auckland Area Office, Takarunga Road, Devonport during normal working hours (9am to 4pm Monday to Friday).
For further information, call Sandra Jack at the Auckland Area Office, (09) 445 9751.
Public concern over wildlife deaths in the Hauraki Gulf
You may be concerned about recent media reports of dog, fish and other marine wildlife deaths in the Hauraki Gulf. DOC is also concerned about this issue and has been working as part of an interagency group led by the Auckland Regional Council to investigate the causes of the deaths. We have included a fact sheet that we hope answers your concerns.
Kind regards,
Amy Cameron
Media officer
Auckland Conservancy
Department of Conservation | Te Papa Atawhai
Auckland Conservancy | 12-16 Nicholls Lane, Parnell | Private Bag 68908, Auckland | New Zealand
DDI: 09 307 4846 | VPN: 7046 | Mobile: 0275 111 222
www.doc.govt.nz
More info:
Treasure Islands - The latest on Motutapu and Rangitoto Island restoration programme [pdf file] 297kb
