Improved survival rates for braided river birds in the Mackenzie Basin

A rare banded yolk in the Mackenzie Basin.  It is one of several bird and insect species that benefit from increased control of predators in the tank.

Liz Brown / Delivered.

A rare banded yolk in the Mackenzie Basin. It is one of several bird and insect species that benefit from increased control of predators in the tank.

The hatching rates of many of the rare birds in the Mackenzie Basin have improved greatly as a result of an initiative to control predators.

Te Manahuna Aoraki, an inter-agency project aimed at transforming the tank into a predator-free zone, released its hatching and breeding statistics for the past year, showing an improvement in survival rates for the country’s rarest birds.

Project leader Simone Smits said that Te Manahuna Aoraki’s team calculated the numbers from monitoring braided river birds over the winter.

“We monitor hatching and hatchling success over the Tasman, Cass, Godley and Macaulay river systems with motion-activated cameras and visual controls,” said Smits.

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“Two of the species we observed, Tarapirhe / Black-fronted Terns and Tūturiwhatu / Banded Dotterels, have significantly improved their breeding success.”

The breeding success of black-fronted terns, a nationally endangered species, is 72-91 percent (the range extends across various braided rivers).

“That is an increase from 27 to 43 percent last season. We monitored 195 nests and the main reasons chicks did not fledge successfully are either because they were older or were lost to flooding, “said Smits.

Tūturiwhatu / Banded Dotterels, classified as Nationally Endangered, had a breeding success rate of 73-91 percent. Historically, the success rate in areas without predator control is 30 percent.

Te Manahuna Aoraki project manager Simone Smits is setting up a tracking device for the life of birds and insects in the Cass River Valley in the Mackenzie Basin.

Robyn Janes / Supplied

Te Manahuna Aoraki project manager Simone Smits is setting up a tracking device for the life of birds and insects in the Cass River Valley in the Mackenzie Basin.

Smits said that since 2018, Te Manahuna Aoraki has expanded predator control across the project area, increasing the safety net from 26,000 hectares to over 60,000 hectares with over 2,200 new traps.

“Not only do these birds live and feed on the woven rivers, they also live near land that is often privately owned.

“We are not surprised by the results. Braided river birds have adapted to flooding, but they have not adapted to the threat posed by pest mammals. Getting rid of as many pests as possible will give all of the native birds and insects in the Mackenzie Basin a greater chance of survival. ”

Banded yolks are prone to predators such as ermines, hedgehogs, and feral cats.

Lucas Smith / Delivered

Banded yolks are prone to predators such as ermines, hedgehogs, and feral cats.

Smits said the project worked closely with landowners in the Mackenzie Basin area.

“This is especially good news as the breeding season for these endangered braided riverbirds is just beginning, and we hope this success will continue to grow over the years,” she said.

“So who knows what the 2021 breeding season will bring, but we hope the future is bright for these amazing braided river birds with our continued focus on removing predators such as ermines, hedgehogs and wild cats.”