Birds of the Manukau Harbour
The Manukau Harbour is both nationally and internationally significant as a feeding and breeding ground for migratory birds. Each summer thousands of Arctic waders that have breed in the Northern summer fly to New Zealand to spend our summer stocking up on food. Most of these birds travel via what is known as East Asian–Australasian Flyway, a route that follows the Western Pacific and Asia and which allows birds to make the journey both way in stages, stopping to rest and eat along the way.
The exception to this is the Bar-tailed Godwit, which makes the remarkable journey from its Alaskan breeding grounds to New Zealand in one continuous 11,000km flight across the Pacific, a journey of eight to ten days without sleep or feeding at an average speed of 60km/h. Since no one ever saw the nest of the Godwit (kuaka) Maori believed that they returned to the spiritual homeland of Hawaiki to breed.
Every summer more than 100,000 Godwits gather in New Zealand, and the Manukau is host to a significant proportion of them. The birds arrive thin and out of condition and in the five months they spend here they put on as much weight as possible to prepare for the next breeding season. When it's is time to leave they make the return journey via the East Asian-Australasian Flyway so as to maintain as much conditioning as possible.
They are joined in the Manukau over summer by other Arctic waders such as Lesser Knots, and Turnstones along with smaller numbers of rarer species. Even during the winter months some of these birds may still be found as youngsters not yet ready to breed will remain here.
In the winter months the Arctic waders make way for New Zealand's own internal migratory birds. Large numbers of South Island Pied Oystercatchers, which breed in the South Island in summer, arrive in the Manukau and can be seen roosting in large flocks in fields and coastal land during high tide.
Other rarer birds are harder to spot. The Wrybill, which numbers only around 5000, migrates North from its breeding grounds in the South Island and up to 1500 of these may make their home in the Manukau over the winter. These birds often make use of the bird roosts that have been set up on the Ambury Regional Park foreshore.
Other birds inhabit the Manukau year round. The threatened New Zealand Dotterel (population less than 3000) can also be found making use of the Ambury Foreshore and the fields of Ambury Farm. The Variable Oystercatcher, unlike the Pied Oystercatcher, stays in the harbour all year in small numbers and some breed here. Australasian Pied Stilts also breed in the Manukau. . There is also a resident population of Royal Spoonbills. Other birds to be seen year round include Caspian and White Fronted Terns, Pied, Little, and Black Shags, Kingfishers, and White-faced Herons.
All of these birds depend on the Manukau and the continued health of the harbour is important to these species. Threats include:
- Runoff of sediment, pesticides and pollutants from farms, development and industry.
- Changes in tidal patterns due to sediment and land use changes.
- Spread of Pacific oysters and expansion of mangroves.
- Pests such as cats, rats and off-leash dogs near nesting areas.
by Bruce Buckman
Bird Migration in New Zealand
Birds of the Manukau Harbour, Tim Lovegrove, Natural Heritage Section, Auckland Regional Council
NZ Birds Online
Photo of Royal Spoonbills at Weymouth, Judi Goldsworthy