60 Years of Migratory Bird Management on the Manukau

The Manukau Harbour is the single most important harbour for migratory wading bird species in New Zealand. Approximately 25% of the national population of wading birds use the harbour at any given time and about 60% of the wading bird population pass through it at some time in their life. From 1960 the city of Auckland used a small part of the harbour to treat it’s wastewater through 515 hectares of oxidation ponds. This comprised of land based treatment followed by four large ponds separated by pond walls (serving as access roads). After the ponds were constructed it was discovered that thousands of migratory wading birds found these walls to be excellent places to roost. Since then, about 20% of the wading bird population that feed in the Manukau Harbour roost adjacent to the Mangere WWTP. The plant staff inadvertently found themselves to be caretakers of some of the best roosting sites in New Zealand. When these ponds were decommissioned and returned to the harbour in 2003 a considerable amount of care was taken to ensure that the birds had viable places to roost. This involved the construction of the largest ‘artificial’ islands roosts in New Zealand. The roosts are actively managed to control weeds and predators, and reconstruction activities are periodically undertaken to remedy the effects of wind and wave erosion. The management of these roosts reflects Watercare’s vision and commitment to operate in a sustainable manner.

This paper reviews the close relationship that these birds have had with the treatment plant since it was commissioned in 1960. It summarises the human history of the harbour and how this has affected these bird populations. It shows the importance of the managed roosts by using data from annual census, providing species specific examples. In addition, this paper discusses how Watercare staff work with ornithological experts to manage these roosts. Involving members of the public to help look after these roosts has been an important community linkage which helps to ensure the conservation work is valued and ultimately successful. Projects continue to involve local groups, schools, and churches who have become involved in conservation and restoration work on and around the roosts. These projects were not only great for conservation, but also great fun for the local community.