Rarest of the rare: Colony of endangered seabirds discovered at PTA

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They’re the little birds that could.

In a discovery that surprised researchers, a nest of the endangered band-rumped storm-petrel has been found at nearly 7,000 feet above sea level on Mauna Loa, making it the seabird’s only confirmed colony in the state.

The breeding site is located on land that’s part of the U.S. Army’s Pohakuloa Training Area, and was documented by the installation’s team of biologists tasked with identifying and protecting endangered species.

“What we’re seeing now is these are really the small relics of the last survivors,” said Lena Schnell, senior project manager at PTA’s Natural Resource Office. “The reason they are up at high elevations is speculatively because of predator pressure.”

But they face threats even that high up. So far, the PTA team has captured six feral cats near the underground nest.

“There are feral cats all over the island,” she said. “… We suspect they’ve learned there’s a food source there.”

Rats and barn owls also pose a threat. The birds are the smallest and rarest seabirds in Hawaii. Schnell said they can fit in the palm of a hand.

The species is found in the Atlantic and Pacific oceans. They return to the same breeding grounds each year, but spend much of their time at sea.

Nests are thought to be located on Kauai, but none have been confirmed, said Schnell, who first began looking for their nests 25 years ago at Hawaii Volcanoes National Park.

According to a research report, which will be submitted to a journal, the birds were first detected at PTA on acoustic monitors from 2010 through 2012. Additional monitoring, including remote camera surveillance and night-vision surveys, from 2015 through 2017 confirmed the nest near Pu‘u Koli.

No military training takes place in that area, Schnell said.

Initially, the team of biologists was looking for calls of the Hawaiian petrel.

Instead, they picked up sounds of the band-rumped storm-petrel, at 10 to 20 times the rate recorded in the park, Schnell said.

“We said something is really going on up there,” she said.

The high point came when a fledgling emerged from the burrow, walked in front of the camera, and took off.

“I want to say it’s one of my crown moments at PTA,” Schnell said. “The seabird project is near and dear to my heart.”

Schnell said PTA will continue studying the colony to learn more about the species and their prospects for survival.

“The Army takes stewardship of the threatened and endangered species under their care very seriously,” she said.

There are 26 threatened or endangered plant and animal species at PTA, including 15 only found in that area, Schnell said.

Email Tom Callis at tcallis@hawaiitribune-herald.com.