Bernie Kelly discusses the colony of tarāpuka found at the Tukituki River mouth in East Clive.

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.

MATTHEW SALMONS/STUFF Tarāpuka chicks tell mum it's lunch time.

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.

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"It's incredible how much damage just one feral cat can do," he said.

ANDRE CHUMKO/STUFF Birds New Zealand representative Bernie Kelly has helped with trapping predators after the discovery of the colony.

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.

ANDRE CHUMKO/STUFF One of the 15 traps Kelly has helped to monitor. A ferret was caught in one recently.

"Most people aren't aware how endangered the black-billed gull is. We're lucky to have them breeding here," Kelly said.

Tarāpuka, distinguished by their long, thin black beaks, are mainly found in braided rivers across the South Island, however they are also scattered around coastal North Island areas and Lake Rotorua.

Regional council terrestrial ecologist Keiko Hashiba was also thrilled the population had colonised there.

JORDAN KAPELLY/STUFF Tarāpuka are the most threatened gull species in the world, and New Zealand's only endemic gull.

"I suspect they all chose this spot because it's basically a great habitat and they all benefit from the predator control. Plus a local champion like Bernie who checks on traps and the colony just about every day makes a huge difference."

Kelly said intense storms had hampered conservation efforts, with one last week causing strong winds to push chicks inland.

Luckily, however, the chicks were caught in marshy areas, and parents looked after them until weather improved. They then herded them back to a stony outcrop.

LUC HOOGENSTEIN/STUFF One distinguishing feature of tarāpuka are their long, thin black beaks.

More than 100 chicks survived out of the original 170, which was a "really good" number. On Thursday, the council was tallying the results of a drone-count of the birds to get a more exact figure.

Main threats to the survival of tarāpuka include habitant disturbance and predation.

Under the Wildlife Act 1953, the disturbance of protected birds, or destroying nests, can result in imprisonment and/or a fine of up to $100,000.