Story: Wading birds
Page 4 – Dotterels
Dotterels are plump little birds that dart around on beaches and mudflats with a comical stop-start action. Internationally, the term plover is used interchangeably with dotterel. The Māori name tuturiwhatu includes New Zealand dotterels and banded dotterels.
New Zealand dotterel
The rare sandy-brown New Zealand dotterel is white underneath until the breeding season, when its chest and belly turn rusty red. Two populations live far apart: the northern subspecies Charadrius obscurus aquilonius (about 2,200 in 2011) lives on sandy northern beaches down to Riversdale in the east, and to Taranaki in the west, although it was once more widespread. Stewart Island is the home of the scarcer southern New Zealand dotterel (Charadrius obscurus obscurus). Into the 20th century, they also bred in the South Island.
The remaining hardy southern birds nest high up on the open summits of Stewart Island’s mountains. There were 218 in 1955, but by 1992 this dropped to 62 because cats preyed on nests at night, killing the nesting parent, which at night is usually the male. The resulting sex imbalance made the population even more vulnerable. But with cat control, numbers had reached over 260 in 2011.
During the winter these birds head down to tidal areas or across to Southland estuaries. They feed on molluscs, sandhoppers and other invertebrates, fish and crabs. Inland they take insects, grubs, earthworms and spiders. The southern subspecies weighs 160 grams.
Dotty about birds
Controversy erupted in 2003 when Transit New Zealand announced plans to move two pairs of New Zealand dotterels away from a North Shore motorway extension. Transit helicoptered in 200 cubic metres of shell to create new nesting sites for the birds.
The strongholds of the northern New Zealand dotterel are long beaches and shallow, sandy estuaries of the north, where they lay two to three olive-brown eggs in shallow scrapes. Young fly at six to seven weeks. They breed at the age of two or three, and can live to 30 or older.
Their decline is partly due to their approachable nature, making them vulnerable to predators. Breeding has been more successful on beaches where wardens have kept a daylight watch. They weigh 145 grams and measure about 25 centimetres. They are a protected threatened endemic species.
The banded dotterel (Charadrius bicinctus) is easily identified by its breeding dress from May to January: a narrow black band on the neck, and a wide chestnut band on the breast. Its back and wings are fawn coloured. It measures 20 centimetres and weighs just 60 grams. It is the most numerous dotterel in New Zealand, and is a protected endemic species.
The banded dotterel breeds in a variety of habitats: coasts, farmland, and alongside lakes and riverbeds. Biggest numbers are found in inland Canterbury and the Mackenzie Basin. Nests are scrapes on compacted sand or dirt, the male making several for the female to choose from. She lays two to four speckled eggs, which both parents incubate. They feed on invertebrates, worms, and berries. After breeding, most of the inland breeding birds (about 30,000 of total population of 50,000) migrate to Australia for winter. They live up to 10 years.
The smaller black-fronted dotterel (Elseyornis melanops), originally a visitor from Australia, bred for the first time in New Zealand in 1958. Although not numerous, they are most common in Hawke’s Bay, where they were first recorded breeding, but have since spread to the lower North Island and to the eastern and southern South Island, with an estimated population of 3,000. They nest in riverbeds after seasonal floods. After breeding they move to estuaries and coasts, feeding on molluscs, invertebrates and worms.
They are light to dark brown on the back and wings. A black band runs from the bill through the eye to the nape, where it joins another from the chest. They measure 17 centimetres and weigh 33 grams. They are a self-introduced native species.