Declining Bird Habitat

Date: 31/03/2016

Photo: of Royal Spoonbills nesting in Weymouth by Judi Goldsworthy

The Manukau Harbour is the most significant shorebird habitat in New Zealand. In the harbour the birds feed on the extensive mudflats at low tide which contain high quality food, gather on the shell banks at high tide and roost along the foreshore. It is essential therefore that the health of the harbour and the mudflats, shellbanks and roosting areas are maintained and that the natural balance is not destroyed.

2011 summer census figures of shorebirds by Ornithological Society

Manukau Harbour 26,171
Kaipara Harbour  20,488
Farewell Spit 17,323
Tauranga – Maketu 10,536
Firth of Thames 9,803

The inner harbour area is of prime importance to the feeding of an endemic shorebird called the Wrybill Plover which occurs at this area in substantial numbers. There are regular flocks in this vicinity of approximately 1,000 birds which is 20% of the world population. The area is also important for the Bartailed Godwit (which migrate to China, North Korea, Siberia and Alaska), Red Knot and South Island Pied Oyster Catcher. The reconstructed foreshore adjacent to Watercare’s treatment facility is home to an increasing number of Royal Spoonbills.

International Importance

At the recent meeting of the East Asian-Australasian Flyway Partnership,  a report was presented titled “New tools for development of the flyway site network: an integrated and updated list of candidate sites and guidance on prioritisation”. This report was prepared by Roger Jaensch dated April 2013.


This report considered potential sites for migratory shorebirds throughout the flyway and used different methods of prioritising criteria to determine lists of candidate sites for each of the countries in the flyway.
 

One of the criteria was the same as a Ramsar listing and under two of the prioritisation criteria the Manukau Harbour was the top of the list for New Zealand. This indicates the importance of the Manukau Harbour in not only a New Zealand context but also internationally. Several of the species of birds that utilise the Manukau Harbour are at their wintering grounds, which is the terminal point of the flyway, and are present as a sizeable percentage of the total population of that species. It is therefore critical that nothing is done in New Zealand that could affect those populations.
 

RAMSAR
The Manukau Harbour is the highest scoring candidate in New Zealand for a new Ramsar listing and preliminary talks have already been held about how to achieve that outcome. The report presented to the meeting of the East Asian-Australasian Flyway Partnership showed that the Manukau Harbour scored very highly under two prioritisation criteria. The first was measuring the proportion of the total size of population which was recorded at the site whereas the second was in relation to the 1% population level for an individual species.
 

These criteria are internationally recognised with the Ramsar Convention applying the 1% population level for new listings.


The Manukau Harbour qualifies for at least 4 species which have more than 1% of their population in the harbour: Wrybill, Bartailed Godwit, Red Knot, and NZ Dotterel.  The Wrybill population in the harbour is about 20% of the total population.
The Ramsar Convention was signed in 1971.

Threats

Increasing sedimentation of the harbour, increasing stormwater and treated wastewater discharges and the spread of mangroves threaten the essential feeding and roosting habitats of the harbour's shorebirds.
 

For further information on Birds of the Manukau click HERE