By Alex Kirby BBC News Online environment correspondent

Safe for now: The Calayan rail

The team of Filipino and UK researchers discovered the bird, a rail, living by a stream in the forests of Calayan.

They think the birds number only about 200 pairs at most, and since they are found nowhere else they might soon be at risk from development pressures.

They say the Calayan rail is flightless "or nearly so": it belongs to a global family including coots and moorhens.

Chance discovery

The expedition was funded by the UK-based Oriental Bird Club and the Rufford Small Grant Committee.

Rufford Small Grants are UK awards of up to £5,000 ($9,215) aimed at small conservation programmes and pilot projects.

The discovery of the Calayan rail is described in Forktail, a journal of Asian ornithology published by the OBC.

The islanders know the rail well

The researchers, the Babuyan Islands expedition team, were surveying the birds, mammals, reptiles and amphibians of the Babuyan group at the northern end of the Philippines archipelago.

On 11 May one of the team, Carmela Espanola, was walking in the forest almost 1,000 feet (300 m) up the slopes of Calayan when she spotted a small group of unfamiliar dark brown birds with distinctive orange-red bills and legs near a stream.

Her notes and photographs, with her recordings of their loud, harsh and rasping calls, helped to establish that the birds were new to science, though not to the island's people, who call them "piding".

The team saw adult and juvenile birds several times over the next few days round their rainforest camp, and estimated there are probably 100-200 pairs in the area, which contains coralline limestone outcrops, caves and small streams.

Reluctant aviator

In order to register the rail as a new species the expedition had to kill one bird, and when they dissected it they found its flight muscles were too weak to carry it far, prompting their conclusion that it is "almost" flightless.

Richard Thomas, or BirdLife International, told BBC News Online: "The Calayan rail has never been seen to fly, but it may be like the Okinawa rail, which flutters up into the trees like a chicken in order to roost."

Unlike most rails, this is a forest bird

Of the 20 species or subspecies of rail that have become extinct since 1600, 90% were flightless.

Most members of the rail family are waterbirds, though in tropical parts of Asia many are forest dwellers like the Calayan rail.

Genevieve Broad, the co-leader of the expedition, said: "I felt sure the Babuyan Islands would hold some interesting discoveries, but I didn't expect to find a totally new species.

Alien threats

"I hope this will bring the recognition these islands deserve as an important site of biological diversity."

The island's population numbers about 8,500 people, and there is thought to be no imminent threat to the rails.

But conservationists are concerned that new roads around the island and to its centre could mean new settlements, habitat loss and introduced predators like cats and rats, which have been implicated in most flightless rail extinctions.

Close-up images courtesy and copyright of Des Allen, rail in forest by Carmela Espanola.