The BBC's big beast takes a virtual walk on the wild side

Today, the BBC launches its most ambitious online project since iPlayer. Ian Burrell reports

I am watching astonishing footage of a large polar bear single-handedly attacking an entire herd of walruses. As the bear sets about a tusked female in an effort to prise away her pup, the familiar voice of David Attenborough tells me that "the bear's claws and teeth can't penetrate her thick hide".

It's only last year that Attenborough himself was a big beast of television, flashing his fangs at corporation executives in defence of the BBC's famed Natural History Unit in Bristol, which was under the threat of cuts. Now he seems to be back on board, a convert to the BBC's multimedia future.

"He's a believer – he sees it and thinks crikey!" says a delighted George Entwistle, the grandly titled controller of knowledge commissioning at the BBC, as he gives an exclusive preview of "Wildlife Finder", perhaps the BBC's most ambitious online project since the launch of iPlayer.

Attenborough is the star of the venture, naturally. He's there on the home page offering his "favourite clips" from his unrivalled career in chronicling the world's worldlife. There are short films of him with a Galapagos giant tortoise, him with Rwandan gorillas, him with an Australian lyrebird as it demonstrates its extraordinary repertoire. No one on Facebook could touch him.

"The web has totally changed how we can link together information, connect people and reach audiences in an on-demand world," enthuses Attenborough, 83, as he introduces visitors to the Wildlife Finder site. " now allows you to browse and search through BBC natural history content from the past 30 years so that you can enjoy the natural world, its animals, their habitats and behaviour as and when you wish."

Attenborough's favourite moments are just a sample from a collection of 500 clips of mammals, fish, birds and reptiles that go live on the new website today, all of them chosen from the vast BBC Natural History archive. By early next year, there will be 3,000 short films available, all between two and eight minutes long.

The project represents a pivotal moment in the history of the BBC, the point when a significant part of the corporation's vast archive is made available to the public in perpetuity. "This is the first really concerted experiment in saying 'What have we got and how do we get it to people in a way that's not going to go away but is simply going to be there,'" says Entwistle, the former editor of Newsnight. "I think it's enormously exciting."

With the BBC increasingly accused by media rivals of spending licence fee money on projects outside its core remit, this is a good example of public service. "We are not commissioning loads of new content here. We are talking about the stuff the licence fee payer has been paying for over decades," says Entwistle.

"We have been like a museum that has been gradually amassing the most amazing collection but has not been open to the public. All you have been allowed to see is the new stuff." He hopes the project will pave the way for similar archive-based sites dedicated to the arts and to science.

Although there is already a substantial amount of natural history footage on the user-generated site YouTube, Entwistle says the key differentiation in the BBC's new offering is the consistency of quality. "The amazing thing about these clips is that they're taken from finished documentaries, so you've got the voiceover and the music, the production values of the original film."

The polar bear, like the lions, the snow leopards, the empress penguins, have been recorded in audio too, and so the bear amid the walruses comes with a link "What do they sound like?" Users are offered background information on the species and its habitat, which Entwistle hopes will be a valuable educational tool. "It's academically structured, we aim for it to be very informative," he says. "It's an adult product intended for adults but I can imagine GCSE students onwards engaging with this with real value."

The site is linked to the BBC's new Earth News service, through which a pair of journalists have been attached to the Bristol unit to pick up stories uncovered by the 70 or so television and radio teams that the natural history office sends on expeditions around the world each year. Recent scoops have included the discovery of new species – including the giant rat and the finger-sized parrot - during the making of the Lost Land of the Volcano BBC1 series, filmed in Papua New Guinea. "BBC news has loved this stuff," says Entwistle. "The truth is that people love animal stories and the giant rat is irresistible."

Another parallel project is Earth Explorers, a site which encourages the teams making these programmes to report via blog, Twitter and webcam on the films they are making, rather than waiting until the end of the production process (which was three years in the case of Life, the big Attenborough-fronted natural history series starting on BBC1 next month).

According to Entwistle, the great naturalist is more relaxed about the evolution of wildlife programmes. "I think he sees that Wildlife Finder draws on the tradition of which he has been a part," he says. "It would not be possible had we not made amazing natural history films for decades and will only go on being good if it's replenished by that same process."