Endangered visitors flocking to Opuha Dam

A flock of tarā puka, regarded as the world’s most endangered gull, has set up a small nesting colony on the downstream weir of the Opuha Dam.

As the species, also known as the black-billed gull, are endemic to New Zealand and critically endangered, Opuha Water Ltd (OWL), which owns and operates the Opuha Dam, has put protection measures in place to look after the special, albeit unexpected, guests.

OWL chief executive Andrew Mockford said the birds were sited at the dam this week, and after liaising with an ornithologist and the Orari River Protection Group, it purchased a number of traps.

These have been set out in the vicinity of the colony to protect the birds from introduced predators such as rats and stoats, Mockford said.

‘‘We have also put in place temporary water level controls, so the birds’ nesting site doesn’t get flooded during nesting and while there are flightless chicks around,’’ he said.

Orari River Protection Group secretary Karen Miles said the discovery was ‘‘very exciting’’.

‘‘To have them at this site is really encouraging, as their population has been in steep decline for a number of years.’’

She said the next stage would be monitoring the gulls during the breeding season.

‘‘It will be interesting to find out how many fledglings there will be,’’ Miles said.

Mockford said being able to positively contribute to the birds’ future ‘‘fits very well with OWL’s long-term strategic goal of achieving an enduring biodiversity corridor centred on the Opihi River system’’.

‘‘We never expected to see this very threatened gull set up in our own backyard. It’s pleasing and very exciting,’’ Mockford said.

According to the Department of Conservation, the number of tarāpuka throughout the South Island has rapidly declined, with some studies recording a population crash of 80 per cent in the past 30 years.

Forest and Bird spokesperson Megan Hubscher said the birds breed in braided riverbeds of the South Island, so their nests, eggs and chicks are vulnerable to attack by all kinds of introduced mammals – dogs, cats, hedgehogs, and humans in particular.

Ornithologist Jim Jolly said the decline of the birds’ population was down to its habitat being encroached upon by both predators and land use change.

‘‘There’s been a steady loss of habitat for the birds, who reside at braided rivers. So many of our braided rivers have narrowed or are now full of weeds,’’ Jolly said.

‘‘What Opuha Water is doing is great, it’s helping create some habitats for the birds.’’