Spring 2019 Bird News

Winter is over, the days are lengthening, and the Northern Hemisphere migrants are starting to arrive.

The beach is a dynamic place and winter storms have helped reshape it. At the northern end the creek has eaten into the bank by Dacre’s Cottage and removed areas that Variable Oystercatchers have bred in, but a new spit has started to form at its mouth. New shell deposits are forming offshore as the beach continues to encroach seawards. A late winter storm removed a lot of sand from the beach between the two creeks and has degraded nesting habitat for New Zealand Dotterel by increasing the likelihood of nests being swept away during summer storms.

NZ Dotterel nest

NZ Dotterel nest

The dotterels lay eggs just above the high tide mark and their nests are vulnerable to storms, particularly when the beach profile has been lowered. In the past two breeding seasons we have managed to produce only two dotterel chicks from the Okura shell spit (at the bottom of the Okura River Road), Karepiro Beach, and the cheniers at Stillwater. While predation by dogs has been implicated in the failure of some nests, most were destroyed over the Christmas and New Year period by king tides coinciding with summer storms.

Dotterel chick

Unfortunately, the replacement nests were also washed away three weeks later when another storm arrived. For the first time in twelve years there were no oystercatcher chicks raised at any of the three sites during the 2018/19 breeding season. In the longer term we are going to remove weed cover on the dunes and cheniers to try and encourage the dotterels and oystercatchers to nest higher up. At present there is too much vegetation for the birds to have a 360 degree view, so they won’t nest there.

Exciting developments with regard to Karepiro include working on a proposal to council to create a scientific reserve (see draft proposal) which would include managing the 30 000 visitors each year – possibly using boardwalks to keep people off the southern part of the beach at high tide and to minimise damage to the dunes – and providing a viewing hide and educational material. We are also working with the developers to restore the wetlands behind the beach to increase biodiversity and provide habitat for rarer birds and inanga (whitebait) breeding sites. Pest control continues on a regular basis, which included poison pulsing during late winter prior to shorebird breeding. To date 132 mice, 3 Norway rats, 9 ship rats, 2 stoats and 7 weasels have been caught this year.

Winter birds

South Island Pied Oystercatcher

The winter flock of South Island Pied Oystercatchers was well down on numbers this winter, possibly a result of the shellfish die-off and consequent depletion of food resources, with a maximum of 172 birds recorded in April. This is about half the maximum numbers recorded during the previous four years. They also left earlier for their southern breeding grounds, with the main flock gone by the end of August. There are always a small number of non-breeding birds that stay over the summer and there were still 31 feeding and roosting in the area in early October. Winter flocks of New Zealand Dotterels (maximum 12 birds recorded in June), Variable Oystercatcher (37 birds also recorded in June), and Pied Stilt (maximum 32 birds in May) roosted at Karepiro over the winter months. Up to four Banded Dotterels were seen this winter until June when they left for their South Island breeding sites, and 3 Royal Spoonbills were also recorded. This is the second winter that these large and impressive birds have visited and stayed for a while.

Return of the Godwits

Bar-tailed Godwit

A small number of Bar-tailed Godwits (up to six birds) overwintered in the bay and were joined by their returning compatriots in September when 33 birds were recorded at Karepiro. This number had increased to 46 birds by early October. Whether the numbers will increase to the long-term average of 120-150 birds is uncertain if food supplies are limited. A first for Karepiro was a Pacific Golden Plover seen in early October.

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