Ulva Island rat eradication
Ulva Island (256ha) is located in Paterson Inlet, Stewart Island. It has high natural values and its relatively unmodified state makes it an important island for the conservation of threatened species. Until recently, it was free of rats after a successful eradication programme, which concluded in 1996.
However, as an open sanctuary with full public access, the risk of re-invasion by rats was always high and the discovery of Norway rats on the island in late 2010 has highlighted that risk. A rat-eradication scheme has been put into place and biosecurity measures have been increased to prevent a re-invasion occurring in the future.
The Sydney Cove and Post Office Bay areas are the most likely areas for a re-invasion due to the high numbers of visitors to these places. Rats can swim ashore from moored boats, stow away in bulk supplies and building materials or even arrive in kayaks, packs and picnic baskets. They are very clever at getting aboard even the best-kept boats without detection, particularly at night.
Ulva Island is a key eco-tourism destination due to its pristine forest and abundant wildlife. Rats were initially removed from Ulva Island over 13 years ago and the island is now home to many endangered birds, including mohua / Yellowhead and tieke / Saddleback. Ulva Island is one of a few 'open sanctuary' islands where the public are able to visit without a permit.
Once Ulva has regained its rat-free status, quarantine measures such as rat-kill traps and bait stations will continue to be maintained on the island, around likely re-invasion points. However, for Ulva Island to remain rat-free, there will need to be a genuine commitment from the visiting public.
Don't visit the island at night and complete a thorough check of boats, packs and supplies at wharves before departure to Ulva Island, not just for rats, but also other potential stowaways - mice, seeds, etc. All boat owners visiting the island should also ensure that boats have rat-traps and/or bait stations aboard and that these are checked prior to each trip. Any rat sighting should be reported immediately to the Department of Conservation office on Rakiura/ Stewart Island (Tel: +64 3 219 0002).
Ulva Island is significant nationwide as part of the leading edge in island conservation management. The project has been invaluable in the knowledge and skills it has provided for the wider programme of removing pest species from other offshore islands around New Zealand. The attempt to re-eradicate rats from Ulva Island will be watched with interest by the international community.
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