Protecting black-fronted terns/tarapirohe in North Canterbury
A multi-year project in the upper Waiau Toa Clarence River is seeing continued protection for the nationally endangered tarapirohe/black-fronted tern.
We are proud to be collaborating with the Department of Conservation (DOC), Toitū Te Whenua Land Information New Zealand (LINZ) and Te Rūnanga o Kaikōura (TRoK) to protect tarapirohe across this unique braided river in North Canterbury.
The upper Waiau Toa Clarence black-fronted tern project is part of our biodiversity programme. Starting in 2015, it is now in its second phase. It aims to increase the regional tarapirohe population through improved breeding habitat.
Tarapirohe only breed on exposed braided riverbeds of the eastern and southern Te Waipounamu/South Island, and the Waiau Toa Clarence population is critically important to the sustainability of the national population.
Funding for this project has been provided by us, DOC and LINZ. Together the three organisations have set aside over $200,000 for the project this year.
Protection for a nationally endangered native bird
Tarapirohe are classified as nationally endangered under New Zealand’s threat classification system, with an estimated population of 5,000-10,000 individuals. They have a predicted rate of decline of 50% over the next three decades if no action is taken to protect them.
Threats to tarapirohe, and other braided river birds, include predators like rats, stoats, ferrets, Australasian harriers, feral cats, and hedgehogs, who prey on tarapirohe nests and eat their eggs. Black-backed gulls are also a major threat to the birds in the Waiau Toa Clarence catchment.
Habitat loss is another major threat, with weeds overtaking areas where the birds breed and providing cover for predators.
Flooding impacts nesting success, though this is a threat these birds are more adapted to.
Project improves nesting opportunities
The Waiau Toa Clarence black-fronted tern project has been working to increase numbers of tarapirohe in the catchment over the last five years, focusing on maintaining and enhancing known nesting sites.
The first phase of the project, which ran from 2015-2020, saw a 'ring of steel' established around tarapirohe nesting sites - predator traps were set around nesting sites in a ring formation.
This provided tarapirohe with predator-free breeding sites. In addition to the predator control, islands supporting nesting colonies were enhanced with deepened channels — a measure that reduces access by hedgehogs — a major predator of tarapirohe eggs.
Weed control was part of the project, reducing the amount of habitat available for predators to hide in.
First phase showed improved nesting rates at protected sites
Our Principal Biodiversity Advisor, Frances Schmechel, said the first few years of the project showed incredibly encouraging results.
“We had two years with dramatically increased breeding rates, six and eight times higher.”
Breeding success was also monitored in areas outside the rings of steel, to compare success rates.
“It was clear from the data that the birds breeding in the rings of steel had a much better chance of nesting success,” Frances said.
From the 2016-2017 season to the 2019-2020 season, the success of chicks surviving to flying (fledging) age was five times higher in the managed areas.
“In one of those years flooding had quite an impact on all the nests, and if that year is excluded then success was seven times higher during the second phase,” she said.
Phase two of project looks promising
The second phase of the project, which kicked off in 2021, saw long trap lines installed on each side of the Waiau Toa Clarence River, to replace the rings of steel used during phase one, as well as additional island enhancement — deepening the channels surrounding nesting areas.
“So far, this season is looking really promising for the breeding success, so it’ll be interesting to see how it compares to the area where we don’t have predator control,” Frances said.
Official data on this year’s breeding season is still being collated.
Frances said she would love to see actions used during this project more widely implemented.
“We hope this encourages other groups and organisations to seek out their own funding and set up similar systems in their local areas.
“The more we can do to prevent these special birds from becoming extinct, the better,” she said.
Connecting the dots across the catchment
This mahi is supported by other work ongoing in the Waiau Toa Clarence catchment. Since 2014, more than a million dollars has been contributed from various agencies and landowners to undertake weed and predator monitoring and control throughout the catchment, all supported by the Kaikōura Water Zone Committee.
Meeting regional targets
- regenerating environment - ecosystems, landscapes and habitats are protected and enhanced, ki uta ki tai;
- the quality of freshwater and coastal waters are protected and improved for community wellbeing;
- and water quantity supports ecosystem health.