Nesting birds face dangers

A unique habitat restoration process taking place on the Aparima River in Wreys Bush is facing new challenges as a result of its success in attracting endangered native birds to nest.

Wreys Bush Concrete director and operator Grant McGregor has been working on restoring the habitat of the Aparima River upstream of the Wreys Bush bridge for more than a decade through utilising gravel extraction techniques to remove sediment, grass and gorse and create low-lying gravel beaches for birds to nest in.

The project, which has been monitored by a Department of Conservation team since 2016, has been successful in attracting birds such as black-billed gulls, listed as nationally critical and facing an immediate risk of extinction, and black-fronted terns, which are nationally endangered, to the restored habitat to nest.

However, DOC science advisor and project leader Clement Lagrue said they were now facing new challenges in the form of predators, four-wheel drives and domestic dogs.

‘‘It’s good, because before Grant did the work, there was so much grass, so there would be no birds. It’s a new problem we’ve created for ourselves,’’ he said.

In recent months, dogs and four-wheel drives have come within metres of the endangered birds nests, with one banded dotterel nest being destroyed by a dog this month.

Lagrue believed people were simply not aware of the colonies of rare birds that had begun nesting on the restored site.

Birds generally nested in the area between August and January, he said.

‘‘We don’t want people to stop coming to the river, it’s just making people aware. It’s not all year round. It’s not everywhere. There’s plenty of other places down stream of the Wreys Bush bridge.’’

Stoats, ferrets, hedgehogs and feral cats – which Lagrue estimated now had a population of about 80 in the Wreys Bush area – were also threatening the restored habitat.

‘‘We knew the predators would be an issue, but there’s been years when basically no chicks have hatched because of the predators,’’ he said.

‘‘Last year, we had a single colony of black-fronted terns with 28 nests. Within a few weeks 25 were gone.’’

It was hoped a new trapping network funded by Environment Southland, involving about 200 traps placed near the river and in farmland around the restored river site, would help the issue.