A small flock of young Hawaiian geese wandered tentatively out of the cage, took a few strokes in the tea-colored water of Kapaia Reservoir and lifted off on their first flight.

Eleven 3-month-old nene were released yesterday morning as part of an arrangement between Grove Farm Co. and the state Department of Land and Natural Resources. Nene are an endangered species and are the Hawai'i state bird. It was the first release of nene at Kapaia.

While a few of the youngsters blundered into the trees yesterday, most landed on clear ground after a couple of swooping flights over the reservoir. The ones in the trees struggled through the underbrush and found their way to the reservoir's edge, where they called back and forth to the rest of the flock across the water.

"They'll be swimming across soon," said Thomas Kaiakapu, wildlife biologist with the state Division of Forestry and Wildlife.

Populations of nene are roughly stable on other islands where they exist, but program has helped the Kaua'i population grow.

"We have 700 to 800 on the island right now," Kaiakapu said. They are found in four general areas: Kilauea, Koloa, Napali and Lihu'e to Kipu.

The Lihu'e population is most dense at the golf courses of Kaua'i Lagoons, but since the links lie next to Lihu'e Airport's runways and the birds can be a hazard to planes, the state is trying to keep that population from growing. The Kapaia Reservoir nene are from chicks born at Kaua'i Lagoons. They were collected from there and raised in pens, eventually being held for the past several weeks in a large pen on a lawn at the reservoir's edge.

Wildlife officials hope the birds have become comfortable with the area and will develop a growing population around the water.

"If we release them at a young age, they can imprint on an area," Kaiakapu said.

Grove Farm has agreed to mow and maintain 8 acres as nene habitat. But because they can fly, as they showed just minutes after being released from captivity yesterday, "we don't have any control over whether they stay or not," said Grove Farm vice president Marissa Sandblom.

"Our objective was to create a safe habitat where nene geese can feed, nest and flourish," she said.

Nene have a number of predators, including pigs, dogs, cats and rats, but mongooses are believed to be among the most significant threats, Kaiakapu said. Kaua'i has no mongoose.

"I think the main reason the nene is thriving on the island is because of the absence of mongoose," he said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.