Rat invasion on Ulva Island

For over a decade Ulva Island has been free of introduced animal pests and is seen as one of the best open sanctuaries in the world.

Over the Christmas 2010 period an alarming discovery was made - rats were found on Ulva Island (including juveniles) which indicated that a breeding population had established itself.

Visitors have always been asked to take responsibility in terms of their personal belongings and check bags and clothing for rats and seeds before setting off to Ulva Island.  Boats are not allowed to be left unattended at the wharf and cannot moor at the island.  But rats can swim.

As a precautionary measure, Ulva Island has a network of traps that are monitored year-round and on average three rats per year are caught and disposed of.  Since Christmas, more than 70 rats have been caught.

With the abundance of food on the island, the Department of Conservation advises that rat numbers are expected to reach maximum population density (regardless of trapping effort) within the next 5-12 months.  The impacts on the island at this point will be severe. 

Ulva Island Charitable Trust is working alongside the Department of Conservation on re-eradication options.

Tissue samples from rats that have been caught are being sent away for DNA analysis to work out if they are related (and may have come from only one invasion event) and to try and establish where they came from. This will be achieved by comparing the DNA of rats on Ulva Island with sample rats from different locations around Paterson Inlet and Bluff.  Some rats are being sent to the vet school at Massey University for further analysis.

Ulva Island ranks highly in the AA guide of 101 things New Zealanders "must do" and each year it draws thousands of international visitors from all over the world.

It is one of New Zealand's premier nature and wildlife destinations and will again be the precious jewel in the crown of the Rakiura National Park.

If you would like to make a donation to help fund this project or future projects please go to our Donations page.  Thank you.

Visit the Department of Conservation website