Scientists say they have found a "lost world" in an Indonesian mountain jungle that is home to dozens of exotic new species of birds, butterflies, frogs and plants.
"It's as close to the Garden of Eden as you're going to find on Earth," said Bruce Beehler, co-leader of the U.S., Indonesian and Australian expedition to part of the cloud-shrouded Foja mountains in the west of New Guinea.
Indigenous peoples living near the Foja range, which rises to 2,200 metres, said they do not venture into the trackless area of 3,000 square kilometres -- roughly the size of Luxembourg or a little over half the size of Prince Edward Island.
The team of 25 scientists rode helicopters to boggy clearings in the pristine zone.
"We just scratched the surface," Mr. Beehler said. "Anyone who goes there will come back with a mystery."
The expedition found a new type of honeyeater bird with a bright orange patch on its face. The bird, known only to local people, is the first new bird species documented on the island in more than 60 years. The team also found more than 20 new species of frog, four new species of butterfly and plants including five new palms.
Team members took the first photographs of Hans von Berlepsch's "six-wired bird of paradise," which appears in 19th-century collections but whose home had previously been unknown.
The bird is named after six fine feathers about 10 centimetres long on the head of the male that can be raised and shaken in courtship displays.
The expedition also took the first photographs of a golden-fronted bowerbird in front of a bower made of sticks, while it was hanging blue forest berries to attract females.
The scientists found a rare tree kangaroo, previously unsighted in Indonesia. Mr. Beehler said the naturalists reckoned that there was likely to be a new species of kangaroo living at higher altitudes.
The scientists visited in the wet season, which limited the numbers of flying insects.
Mr. Beehler, who works at Conservation International in Washington, said the area was probably the largest pristine tropical forest in Asia.
Animals there were unafraid of humans.
Mr. Beehler said the Indonesian government was doing the right thing by keeping the area off limits to most visitors -- including loggers and mineral prospectors.
The scientists cut two trails about four kilometres long, leaving vast tracts still to be explored.