The Department of Conservation and the owners of Great Mercury Island are working together to remove rats and feral cats from the island.

Date:  17 July 2014

Work has begun on making Great Mercury Island/Ahuahu, a pest free sanctuary for native wildlife. 

The Department of Conservation (DOC) and the owners of Great Mercury Island - Sir Michael Fay and David Richwhite - are working together to remove rats and feral cats from the island. 

“The level of community support for this project has been amazing” said DOC Project Manager, Pete Corson. “The work to sustain a pest-free Great Mercury Island begins now and it is up to all of us to make sure the island remains pest free. The message is simple. Check your boats and gear for stowaway pests, tell everyone Great Mercury Island is pest free and enjoy a pest free Great Mercury Island. Thank you all for your continued support”.

Approaching Huruhi harbour, Great Mercury Island. Photo: Kelly Smith.
Approaching Huruhi harbour, Great Mercury Island

Removing these predators involves precisely targeted aerial applications of bait using specially designed buckets carried by helicopter. The helicopter pilots use satellite navigation (GPS) technology to ensure the bait is spread only where intended. 

After three years of careful planning, helicopters began the first bait application this week on Tuesday July 15. Weather permitting, this first application, covering the island, was due to be completed by Thursday July 17. A second, and final bait application, is scheduled to be carried out on Great Mercury from three weeks, weather permitting. 

The public is being kept off the island during the bait application to ensure they and the people involved in the operation are kept safe. People on boats need to stay 200 metres away from the island’s coast during the application, to ensure they and the pilot stay safe.;

Removing rats and feral cats from Great Mercury will make the island safe for resident populations of native birds including kaka, kakariki, and little blue penguins, plus native geckos, skinks and insects. It will also enable DOC to move endangered native wildlife onto Great Mercury in the future.

The rats on Great Mercury also pose a threat to native wildlife on six other islands in the Great Mercury Group. That’s because several of these islands are within a rat’s swimming distance and rats could spread from island to island.

These other islands - Red Mercury, Green Island, Atiu/Middle island, Kawhitu/Stanley Island Moturehu/Double Island and Korapuki  - are all pest free nature reserves managed by DOC. The islands are nesting sites for seabird species of international importance, such as Pycroft's petrel. 

DOC has used aerial applications of bait to safely and successfully remove pests from more than 60 islands. This includes Tiritiri Matangi, Little Barrier/Hauturu, Motuihe, Rangitoto and Motutapu in the Hauraki Gulf Marine Park. These islands now provide safe pest free havens for endangered wildlife. 

For example, Motutapu - 30 minutes by ferry from downtown Auckland - was declared pest free in August 2011. It now provides a safe home for 21 critically endangered takahē. There are only 260 takahē in total. 

Pest free Motutapu is also helping secure the survival of Coromandel brown kiwi. Coromandel brown kiwi have been moved to Motutapu to establish a breeding population on the island. In the future Coromandel brown kiwi from Motutapu will be returned to the Coromandel boosting the number and genetic diversity of this rare kiwi.


Local contact: Aniwa Tawa
+64 7 869 5639

Media contact: Nick Hirst
+64 9 307 4866 or +64 27 704 7773

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