Habitat restoration project proving its worth for endangered birds

Grant has spent the last decade working extensively with DOC and Environment Southland, finding a way through the concessions and consents required to undertake gravel extraction and restore braided river habitats at the same time.

On the Aparima River, near Wreys Bush, an exciting project has reached the halfway point and results are starting to be seen, while challenges continue to present themselves.

The gravel extraction process has been changed to mechanically remove the accumulated sediment and weeds (grass, gorse and broom) smothering gravel banks over large areas rather than digging ponds. Gravel is then redistributed, creating clean, low beaches for the birds to return and nest – more like the original braided river. It’s been a learning curve understanding how to create the best living and nesting conditions for different bird species and Grant says watching them has been fascinating.

“The gulls aren’t that fussy, but the terns definitely are – they like particular gravel depths and even seem to prefer areas with scattered dead grass clumps.”

He’s also learnt a bit about their personalities. As a consent requirement, he must not dig when the birds are nesting, but he’s finding the gulls are increasingly hunting the digger out and almost playing around it.

“They’re quite entertaining to watch and will even land on the digger.”

While the original vision was Grant’s, he pays credit to many people who managed to turn his vision into a plan, build on it and are continuing to work with him to see it through.

DOC has been leading a project on site since 2016, monitoring gains and issues associated with Grant’s alternative gravel extraction methods. Clement Lagrue (science advisor ecosystems based in Dunedin) took over as lead for the 10-year project in 2020 and is excited by the progress being seen.

“The monitoring project we’re undertaking focuses on nesting success, diversity of species and numbers. The restoration of the river has definitely attracted the birds back to the river, providing great nesting and feeding habitat for birds we know are struggling.”

However, Clement says they are now dealing with a new issue – predators. Ferrets, rats and feral cats are having a huge impact on nesting birds.

“Nest-predation has been a constant issue since the beginning of the project. We now need to protect those birds we are attracting back to the river and monitor whether this makes a difference.

“Last nesting season, a black-fronted tern colony established at the restored site, which had 28 nests. Within one week 25 of those had been raided by predators.”

The problem with predators has led to an additional aspect to the habitat restoration trial, which involves setting up a network of traps, assisted by funding from Environment Southland’s Environmental Enhancement Fund.

The project team plans to get 200 traps in place for the upcoming bird nesting season, and they are getting good support from landowners whose properties border the river. Predators travel some distance to get to the river and the trapping needs to intercept them before they get to the birds.

“We cannot do this without landowner involvement,” Clement says.

Grant said the project is actually having some additional benefits in terms of relationships and understanding different perspectives. A number of university students and DOC seasonal workers have been involved in the monitoring programme and they need to make contact with landowners to access the nesting areas.

“It’s been great because the farmers are taking an active interest in the project and can tell the students where the nests are and the students are seeing farmers in a different light to perhaps what they might have envisioned – it’s definitely turned into a bit of a PR exercise.”