There are two distinct areas in the East Harbour Regional Park – the large northern block is called the Northern Forest (the other area is the Parangarahu Lakes). This part of the park comprises the bush covered hills between Eastbourne and Wainuiomata which are clothed in some of the best beech/rata forest in the Wellington area. The damp valley floors contain lush semi-swamp forest including kahikatea, pukatea and nikau palms. MIRO volunteers undertake trapping and species monitoring with the aim of restoring ecosystem health by reducing pests to low levels. A “mainland island” has been established in the part of the Northern Forest between the Butterfly Creek picnic area and Mount Hawtrey. In 2006 Greater Wellington established an intensive rat-control programme in this 300 hectare core area using closely spaced poison bait stations.