The birds in question, though, are threatened black-billed gulls (tarāpuka), New Zealand’s only endemic gull, typically found on braided rivers in the South Island.
The project, the Thomsons Catchment Project, near Omakau, is a farmer-led initiative aimed primarily at reducing sediment flow coming out of the Thomsons Catchment into the Manuherikia River.
However, the construction of a nearly 1km meander through 5ha of new wetlands appears to have created a habitat now being used by a variety of birds.
The project manager, the Department of Conservation and Otago Fish & Game all lauded the news following the first bird monitoring of the site after construction of the Central Otago wetland took place this week.
Otago Fish & Game officer Ben Sowry said more than 350 gulls had begun nesting in the first year after the wetland was established.
Fish & Game had been involved as a liaison partner with Thomsons wetland for the last four years after the organisation was approached to conduct bird surveys for the years before and after the wetland’s development, Mr Sowry said.
"The first two years of the survey, mallard ducks were the predominant species.
"In the third year, the survey was not completed as the wetland was under construction.
"The water was drained and there was heavy machinery in the wetland at the time."
This year, despite none being previously counted in the area, there were 353 black-billed gulls counted this week.
"It’s exciting to have these birds showing up and successfully breeding so early in the development of the wetland," Mr Sowry said.
And while a "massive decline" in mallard numbers was unfortunate, he said it was likely those birds had migrated to ponds nearby and it was hoped they would return to the wetlands after further planting.
Thomsons Catchment Project project manager Nicola McGrouther said everyone involved in the project was very excited by the unexpected presence of the gulls — and there was now interest among those developing the wetlands to set up an ongoing bird monitoring group to survey the increasing bird biodiversity.
The gulls arrived in September, disappeared after a flood, but later returned to begin breeding after the group finished planting 41,000 carex secta (swamp sedge) plants in the area.
It had transformed an area that was once simply paddocks with duck ponds, she said.
The shallow water is also proving popular with pied stilts.
"Early on in the piece we put some rocks in, white rocks go through the middle as a bit of a flood zone — as a bit of a pressure valve if there’s a big flood, so that the water doesn’t back out too much.
"And they [gulls] have taken a shine to the rocks, which is awesome," Ms McGrouther said.
