The animals came in bit by byte

That first time around, or so we are told, the animals were herded in two by two, doubtless encouraged by the odd prod from Noah and sons.

Due to be launched this Tuesday by wildlife broadcaster Sir David Attenborough, ARKive is the brainchild of the late Christopher Parsons, the visionary head of the BBC’s Natural History Unit, and has been created by the Wildscreen Trust, the Bristol-based organisation which hosts an annual international festival of nature documentary film-making. As the Hollywood of the wildlife documentary, base for the BBC and Granada natural history units - as well as numerous independent producers - Bristol makes an appropriate home for this digital "safe haven" for often irreplaceable documentary materials which, like their subjects, may be at risk of vanishing. ARKive is an online compendium of biodiversity, its digital images backed by fact files and web links, but it is also a warning beacon of advancing species extinction. In Bristol the research team is "madly trying to get as much content as possible on to the website ready for it to go live," says the project’s manager, Harriet Nimmo. "The launch is just the beginning, not the finished product."

The project’s species records are organised into two "chapters", one covering UK plants and animals, some 600 of them to date, from footage of boxing brown hares to the only known photographs of the Snowdonia hawkweed, recently rediscovered after a gap of 50 years.

Also underway is the "Globally Endangered Species" chapter - a potentially massive undertaking, considering that the World Conservation Union lists some 6,000 animals and 33,000 plants as endangered. ARKive is beginning by locating and storing records of the 500 species seen as best representing the range of lifeforms most at risk. Thus the archive now harbours the only surviving film of the thylacine or Tasmanian tiger, a carnivorous marsupial presumed extinct since the last known example died in a zoo in the 1930s; and the last known pictures of the vividly coloured golden toad of Costa Rica, now vanished. As an illustration of the timely nature of the operation, take the case of Spix’s macaw, declared extinct three years ago: footage of the last male found in the wild now rests with ARKive.

Nimmo stresses, however, that the project should not be seen purely as "a sort of doomsday collection of things which have become extinct. These films and photographs are really the most powerful and emotive way of raising awareness, celebrating the variety of life on Earth. There’s amazing material here which was scattered all around the world and which is now in one collection and maintained and preserved for future generations in the public domain."

Funded by Hewlett Packard Laboratories (Europe) and the Heritage Lottery and New Opportunities funds, the archive has tapped materials from the more obvious major sources such as the BBC, Granada, international state broadcasting corporations and National Geographic magazine, as well as from small conservation organisations and individuals. Important contributions welcomed in recent months include the complete archives of Eric Ashby, the influential English naturalist and film-maker who died in February, while the collection of another lost film-maker, Dieter Plage, who fell to his death while filming from a hot-air balloon in 1993, is awaiting collection in a bedroom in Norfolk, according to Nimmo. "And just yesterday we had Cornell University in the US, who have the second biggest collection of natural history sound recordings in the world, giving us lots of stuff, including footage of very rare birds like the ivory-billed woodpecker, which went extinct in the 1930s."

ARKive has also accumulated a vault full of associated materials, including around 2,000 wildlife videotapes of entries to the Wildscreen festival, and books, many of them collectors’ items. It also has videotaped interviews with the likes of Attenborough, Desmond Morris - and Parsons himself who, 21 years ago, when head of BBC’s Natural History Unit, produced a prototype CD during an interview with Angela Rippon and predicted the day when such discs would store information and images that would be accessible to home computer-users.

As much as being a launch party, Tuesday’s fling will be a tribute to Parsons, whom Attenborough, a long-time friend and collaborator, described at the time of his death as "one of [the natural history world’s] most influential, most imaginative and, certainly, most self-effacing champions ... His life enriched millions who never knew him, or would recognise his name."

Attenborough regards ARKive as "an invaluable tool for all concerned with the well-being of the natural world. "Over the past few decades, a vast treasury of wildlife images has been steadily accumulating, yet no-one has known its full extent - or its gaps - and no-one has had a comprehensive way of getting access to it. ARKive will put that right."

Other leading scientists and commentators have welcomed the project: Edward O Wilson, the Pulitzer prize-winning entomologist, author and crusading environmentalist, regards it as "a noble project, one of the most valuable in all of biology and conservation practice".

To what extent ARKive will educate and inspire as an information source and celebration of biodiversity, or become an online memorial to an ever-increasing tally of vanished species, remains to be seen. In the words of Andrew P Dobson, professor of ecology and evolutionary biology at Princeton University, "these are images that we should conserve with an intensity equal to that devoted to our greatest works of art. They are images that will haunt our grandchildren."

From 20 May, ARKive becomes accessible on the internet on www.arkive.org