At-risk gulls return to Opuha Dam

For the second year in a row, endangered tarapuka (black-billed gull — Chroicocephalus bulleri) are nesting on the lower weir structure at the Opuha Dam, near Fairlie.

Tarapuka are endemic to New Zealand and their population is in decline, especially in the South Island. They were once listed as the most endangered gull in the world, a status only recently lifted following better understanding of their remaining numbers.

Nevertheless, the species is in trouble, so Opuha Water Ltd (OWL), which owns and runs the Opuha Dam, is ensuring the birds are disturbed as little as possible to let them get on with nesting and raising chicks.

OWL chief executive Andrew Mockford said there were two colonies of the gulls on either side of the control structure on the lower weir of the dam. The larger northern colony had about 210 birds present and the smaller southern colony had about 57 birds.

"Most birds are sitting on nests with about two eggs per nest. The birds have been incubating for about two weeks of their 24-day incubation period. After hatching the chicks will go into creches for a further 30 days, taking the breeding period through to late January.

Mr Mockford said OWL staff were taking all necessary measures to minimise disturbing the birds while carrying out their essential duties.

"Clearly Opuha Water has provided a safe nesting site on the weir, encouraging the birds to return. The site is fenced off from public access and we’ve also set out some traps to protect the birds from introduced predators."