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History of the Mainland Island Restoration Operation (MIRO)

A Landcare Report in 1995 showed the extent of damage being caused by possums on vegetation in East Harbour Regional Park. Foliar browse was found to be particularly heavy on a range of broadleaf trees and especially on the northern rata. MIRO volunteers started trapping possums around Hawtrey in the rata forest, while Hutt City Council provided householders adjacent to the bush with Timms traps to catch possums on the urban fringes. This became known as the Possum Busters campaign. It continued for a number of years but gradually wound down. MIRO however continued to trap within the Park, moving traps as areas were cleared.

In 2004 when GWRC took over as Park managers, they proposed the set-up of a park-wide network of possum traps and agreed to fund it if MIRO would provide volunteers to service the traps. The network which now extends right across the 2000ha of the northern forest block comprises over 60km of trap-lines and currently there are 477 possum kill traps and rat bait stations. The network continues to be added to as required.

After possums the next predator to be targeted was rats. Attempting to control rats across the Park was not feasible - rather a Mainland Island of approximately 300ha centred on Butterfly Creek catchment was selected. In lieu of paying for the possum control across the northern forest which MIRO were already carrying out, GWRC commited to funding the establishment of a grid of rat bait stations 150m by 100m inside the Mainland Island. Contractors are employed to re-stock bait stations with bait every two months troughout the year.

With the successful control of pests, MIRO has translocated to the northern forest block Mainland Island 108 North Island Robin - 28 sourced from the Wanganui Conservancy (2008), 40 from Kapiti Island (April 2011) and a further 40 from Kapiti Island (April 2012).  The ongoing monitoring and banding of the Robins is now part of MIRO’s responsibility.


Successful East Harbour Breeding Pair of Robins translocated from Kapiti Island

A Nursery to assist restoration of the Parangarahu Lakes Area was set up in 2005.  The lakes block (now known as the Parangarahu Lakes Area) was added to the Park after the cessation of a grazing lease to a local farmer in 2004. The area was to be allowed to regenerate naturally but to speed up the process MIRO proposed the establishment of a nursery to grow eco-sourced trees to attract birds and facilitate the spread of native seed into areas of gorse. 

Planting Trees from the MIRO Nursery at the Lakes Block

GWRC commissioned a plan to guide the restoration. This plan identified the tree species required and also identified suitable plots for selective planting in the area. The MIRO nursery was established in 2005 and the first 800 trees from there were planted in the winter of 2007 in a specially fenced plot near Lake Kohangapiripiri to protect the small trees from hares. MIRO and GWRC have now planted over 6,000 trees from the nursery in 5 plots around the lakes with GNS Science providing the land for the nursery at their Gracefield site.  MIRO will be working with GWRC and the Taranaki Whanui on best practice management of the Lakes Area.

MIRO is now working with GWRC on what role it would like MIRO to play with the newly acquired Baring Head block.