Birds New Zealand representative Bernie Kelly is overjoyed a rare breeding colony of tarāpuka has taken up residence near his home in Hawke's Bay.
Every day Kelly checks on the colony of more than 300 nests, first found at the Tukituki River mouth last October.
He was recruited by the Hawke's Bay Regional Council to mind the site, believed to be one of the largest ever found in the North Island.
The Birds New Zealand Hawke's Bay representative, has recently been setting extra traps around the area to find a feral cat and other predators threatening the population.
"It's incredible how much damage just one feral cat can do," he said.
Alongside council staff and the Department of Conservation, he ended up catching the offending feline after about one week.
Tarāpuka, or black-billed gulls, are the most threatened gull species in the world, and New Zealand's only endemic gull. Populations have declined by as much as 80 per cent in recent years, resulting in its threat status being upgraded to critical in 2013.
The colony's success has been put down to its location, being about 700 metres away from public access, at the water's edge and on a shingle beach.