A Masterton conservationist was horrified to see a rare native dotterel in a dog's mouth on Wairarapa's east coast, and is urging a quicker action from the council to protect the birds.

Several New Zealand dotterel established a colony on the Riversdale Beach shoreline a few years ago, but they have been facing considerable natural and manmade pressures.

Conservationists have been clamouring for tighter restrictions on dogs, which have been allowed free rein on the beach.

SHELLEY OGLE Native dotterels have been struggling for several years to establish a nesting colonly at Riversdale. (File photo)

Masterton conservationist Tony Price visited the dotterels' nesting site at the northern end of the beach a few days after a recent storm, and saw that the fenced-off area had virtually been wiped out.

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To add insult to injury, he spotted a dog carrying a dead dotterel.

PIERS FULLER/STUFF Masterton conservationist Tony Price, who saw a terrier with a dead dotterel in its mouth, says signs are not enough to protect the birds.

"I was absolutely horrified to see a dog with an adult dotterel bird in its mouth. It was a fox terrier, and it definitely was a dotterel," he said.

Joanna McVeagh, of Birds New Zealand, said Price's report was a "horrifying scenario". "It's completely barmy that that is designated as an off-leash dog exercise area."

She welcomed news that Masterton District Council had a proposed change in its bylaw out for consultation, but said its reluctance to do so earlier had contributed to the problem.

PIERS FULLER/STUFF A banded dotterel spotted at Riversdale Beach this week, despite a storm surge destroying part of its nesting habitat.

Council manager strategic planning Tania Madden said the proposed bylaw would require dogs to be on a leash on the beach from August 1 to January 31, which coincided with the birds' breeding season.

Conservationist and councillor Chris Peterson said the Riversdale dotterels were a "pretty important colony".

"At the northern end from August to December you should have a situation where dogs are prohibited, or have to be on a leash."

PIERS FULLER/STUFF Signs have been put up at the nesting areas urging people to keep dogs on a leash, but conservationists want a bylaw in place.

He pointed out that, under the Wildlife Act, people could be fined of up to $100,000 for interfering with the nesting of endangered birds.

However, he said dotterels did not help their own cause by nesting in places that were easily accessible to predators.

"This is where push comes to shove with all this biodiversity stuff. Do we just say, 'Forget it, it's all too hard'?"

SHELLEY OGLE Dotterel eggs, lead in the sand, are especially vulnerable. (File photo)

The Department of Conservation does not actively manage the colony, though the regional council has carried out predator control and put up fences.

DOC spokesman Jim Flack said beachcare groups, local volunteers and DOC staff had been raising awareness of threats to dotterels, fencing nests and dealing predators in some sites.

Native dotterels have been growing in numbers and expanding their range over the past 20 years, thanks to community conservation effort on beaches around the North Island, particularly from East Cape to North Cape, where the bigger populations are.