To boldly go where no one has gone before, one group of scientists didn't have to venture into space. They found a lost world right here on Earth.

"It really was like crossing some sort of time warp into a place that people hadn't been to," said Bruce Beehler of the wildlife expedition he co-led in December into the isolated Foja Mountains on the tropical South Pacific island of New Guinea.

During a 15-day stay at a camp they had cut out of the jungle, the conservationists found a trove of animals never before documented, from a new species of the honeyeater bird to more than 20 new species of frogs.

"We were like kids in a candy store," said Beehler, a bird expert with Conservation International in Washington, D.C. "Everywhere we looked we saw amazing things we had never seen before." (Read: Birds on Islands Are Losing the Ability to Fly.)

Boggy Lakebed

The team spent nearly a month in the Foja Mountains on the western side of New Guinea, the part belonging to Indonesia. They used the lowland village of Kwerba (population: 200) as a base from which to survey area wildlife and plants.

From Kwerba, one part of the team ventured by foot up the mountains. Another group helicoptered to a boggy lakebed near the range's high point.

Within minutes of landing, the scientists encountered a bizarre, orange-faced honeyeater bird. It proved to be a new bird species, the first discovered in New Guinea since 1939.

On the second day the lakebed group made another suprising find when a male and female Berlepsch's six-wired bird of paradise came into the camp to perform a mating dance.

Until now the homeland of this "lost" bird had been unknown. It was the first time Western scientists had even seen an adult male.

"We had forgotten it even existed," Beehler said.

Conservation International, the Indonesian Institute of Sciences, and the National Geographic Society funded the expedition. (National Geographic News is part of the National Geographic Society.) The 12-person team included U.S., Australian, and Indonesian scientists.

Tree Kangaroo

The local Kwerba people aided the researchers.

Traditionally considered the owners of the Foja Mountains, the Kwerba hunt game and collect herbs and medicines from the fringes of the pristine forest.

Giant crowned pigeons, small wallaby kangaroos, cassowary birds, tree kangaroos, and wild boars are abundant within an hour's walk of the village. The Kwerba told the expedition members the locals had never ventured farther into the forest.

Walking from the Kwerba village to the mountain camp, the Kwerba said, would take about ten days.

"This is an area where there is apparently no evidence of humans," Beehler said.

The Foja Mountains, however, are not entirely undiscovered.

In the 1970s scientist Jared Diamond—now famous for his best seller Guns, Germs, and Steel—became the first Westerner to penetrate the Foja range. He did not, though, visit the same area as Beehler's group.

"He set the stage for all the work we did and gave us a lot of hints as to what we should look for," Beehler said.

Beehler and his team located a series of display bowers—chambers or passages built by males to attract mates—of the golden-fronted bowerbird. Though Diamond had discovered the species, Beehler's team took the first photographs of the bird.

Another highlight of the expedition was the discovery of a population of the golden-mantled tree kangaroo. It was the first record of this species in Indonesia.

Meanwhile, reptile experts documented 60 different kinds of frogs, including more than 20 new species.

Perhaps the most exciting discovery was a tiny frog less than 14 millimeters (0.6 inch) long. The animal that was detected only when it produced a soft call from among leaves on the steepest part of the forest floor.

"The sheer diversity of frogs and the number of species never before seen by Western scientists demonstrates just how poorly the frog fauna of the Foja Mountains, and indeed of the island of New Guinea, has been documented," said Steve Richards, the expedition co-leader.

A botanical team collected more than 550 plant species, including at least five previously unknown woody plant species. Entomologists encountered more than 150 insect species, including four new ones.

Virgin Territory

In the Foja Mountains there are more than 740,000 acres (300,000 hectares) of old-growth tropical forest that are apparently never visited by humans.

"This virgin territory has not been impacted by humans," so plant and animal species are at natural population levels, Beehler said.

There is no immediate conservation threat to the region, which was designated a wildlife sanctuary by the Indonesian government more than two decades ago.