WAILUKU, Maui — A day after state workers and conservationists found 50 wedge-tailed shearwaters that had been killed by a dog at the Mo'omomi Beach Preserve on Moloka'i, they found 10 more dead birds at the nesting site.

But nesting season is still beginning for the large, dark-brown migratory seabirds, and workers banded 96 healthy adults at Mo'omomi on Thursday evening, and found two more that were already wearing bands, said state wildlife biologist Fern Duvall.

"That's the good news," said Ed Misaki, director of Moloka'i programs for The Nature Conservancy. "The birds are still coming in."

The Mo'omomi Preserve is managed by The Nature Conservancy and is open to the public by passes issued by the agency.

Pets are not allowed in the area. "That's the reason why," Misaki said, referring to the dead birds.

Nature Conservancy workers were at Mo'omomi to do weed control when they found the first bird carcasses Wednesday, he said.

Only two or three birds were nesting in the area when The Nature Conservancy started managing it in 1999, so crews feel an emotional connection to the growing flock, Misaki said.

"It's an indicator. It's like a thermometer — it's telling us we're doing something right," he said. "So when something like this happens, we really feel it."

The workers found a skinny dog that was wearing a collar with a bird still in its mouth, he said. The dog was taken to the Molokai Humane Society.

"It was obviously a pet that got away," Duvall said. "Pets can have a real severe impact on natural wildlife."

Shearwaters live their lives at sea but return to land to nest in burrows, staying there and taking turns flying out to sea to fish until their chicks fledge. Because the birds live underground and are awkward and helpless on land, they are an easy target for dogs and cats, as well as rats and mongooses.

"Now is the start of the annual seabird nesting period," Duvall said. "People should be aware of that."

Warning signs are posted at known nesting sites, but they will help only if humans keep their pets away from the areas.

"The animals themselves don't read," Duvall said.