KAILUA, Hawai'i — High in a Big Island forested oasis surrounded by lava, scientists have made their first releases of endangered Hawai'i creepers.

Four of the birds raised under a San Diego Zoo conservation program were placed Friday into Kipuka 21, a fenced island of vegetation along Saddle Road, which cuts between the peaks of Mauna Kea and Mauna Loa. The first two creepers were taken to the area two days earlier.

During the week's "soft release," the creepers were placed in a aviary high on a scaffold in Kipuka 21. Provided with water and food, the creepers will get a chance to become familiar with their surroundings before they are set loose, said David Leonard, wildlife biologist with the state Department of Land and Natural Resources.

Within three weeks, the Hawaii Endangered Bird Conservation Program expects to release 11 'akepa, one of the smallest species of creeper.

The 'akepa will be set free in family groups, including a youngster hatched this spring and believed to be the smallest bird ever hatched in captivity, weighing less than a gram, or 1/30 of an ounce.

"That little guy will go out with a pseudo-family group. After we finished rearing it, we fostered it into a family," said Alan Lieberman, the Zoological Society of San Diego's program manager for the Hawaii Endangered Bird Conservation Program.

Scientists hope the birds will stay in the area, bringing the total number of native bird species at Kipuka 21 to seven.

The newly released birds were raised at the Keauhou Bird Conservation Center.

The Hawai'i creeper is olive-green with a white throat and a dark gray raccoonlike mask. An active rain forest bird, it feeds primarily on insects gleaned from branches and tree trunks, and also on nectar. The Hawai'i creeper travels in family groups and sometimes flocks with other native birds.

The male 'akepa is bright red-orange; the female has a greenish top and yellow belly. They gather in small flocks and nest in tree cavities. Their diet consists primarily of insects and spiders.

They use their odd-shaped bills to pry open 'ohi'a buds, small seed pods, and galls in search of food. They have been known to drink nectar from 'ohi'a and other flowers. Their "kee-wit" calls are quiet and their songs are a short, warbling trill.

The Hawai'i creeper was listed as an endangered species in September 1975 under the Federal Endangered Species Act. The 'akepa and Hawai'i creepers are endangered because they exist only on the Big Island, in a narrow band of forest between 4,000 and 6,000 feet elevation.

Kipuka 21 is ideal for releasing such birds, and for bird watchers to catch a glimpse of them. Natural lava flows allow visitors to stand level with the forest canopy. The area has been the subject of focus by the state Division of Forestry and Wildlife, where volunteer-aided efforts have created trails and fenced out rooting feral pigs. Plans are also in the works to purge the area of invasive predators, such as feral cats and mongooses.

"The kipuka is a very special place where several species of rare Hawaiian forest birds can be seen regularly," said Scott Fretz, wildlife program manager for the Division of Forestry and Wildlife.

"It's right off Saddle Road, so it is very accessible," Fretz said. "We are in the process of developing a nature trail, overlook and parking area so that residents, visitors and schoolchildren can experience a unique Hawaiian rain forest and learn about Hawai'i's wildlife and habitats. The site is not yet open to the public, but we expect it to be in a year or so."

Leonard, the wildlife biologist with the state Department of Land and Natural Resources, said scientists hope the creeper and 'akepa will stay in the area, allowing visitors to view the seven native species in their natural environment.

"That's really exciting," Leonard said. "This project has a lot of potential to make our jobs easier."

Biologists believe the birds were native to the area in the past, but they haven't been spotted there for several years. Invasive predators have taken a toll on the species, but scientists believe the birds will thrive in the protected area.