Shorebird census surprise on Lake Wairarapa

A record number of nationally vulnerable shore bird species has been counted on the shores of Lake Wairarapa in a recent survey.

A total of 6,773 waterfowl belonging to 26 different species were recorded in the one-day census carried out in July. This number included a surprise find of 281 dabchick which is a record number for the lake.

"This species has a total national population of around 2,000 birds and is only found in New Zealand. The highest comparable record for monitoring carried out between 1984 and 1994 was less than 50 dabchicks at this location, so 281 birds represents a surprising increase in the population," says Greater Wellington Regional Council's Team Leader Terrestrial Ecosystems and Quality, Philippa Crisp.

"Volunteers and staff from Greater Wellington Regional Council, Department of Conservation and Birds New Zealand scanned 18 km of shoreline to complete the counts, often having to walk or wade through unusually high water, dodging obstacles such as drainage ditches, electric fences and treacherous underwater potholes dug out by foraging black swans."

Also spotted were 250 of the world's most endangered gull species, black-billed gulls, five Australasian bitterns and an unusually high count of eleven black-fronted terns. Australasian bitterns and black-fronted terns are both classified as nationally endangered.

A single white heron only known to breed at Okarito Lagoon (West Coast) and a single little egret, both listed as nationally critical species, were also recorded. These two species are only ever seen in very low numbers and appear to be annual winter visitors to Lake Wairarapa.

Among the few species to have declined over the survey period is the South Island pied oystercatcher. The decrease in this species numbers is likely due to threats to the birds South Island breeding grounds.

Hugh Robertson, Principal Science Advisor, Department of Conservation says the data will not only provide an updated picture of the status of shorebirds at Lake Wairarapa it will also contribute to efforts to estimate the regional population sizes and threat rankings of our locally-occurring bird species, contribute to national census of NZ shorebirds and be used to lobby for improved protection of shorebird habitats along the length of the East-Asian/Australasian Flyway.

The New Zealand dabchick, Poilocephalus rufopectus

Photo courtesy of Duncan Watson