By Alex Kirby BBC News Online environment correspondent

The world's biggest colony of black-browed albatrosses now faces a far more secure future.

The colony is on one of two islands in the Falklands group in the south Atlantic.

Both islands, which are home to several other bird species, have been given to a US charity, the Wildlife Conservation Society (WCS).

The albatrosses have been declining recently, with many experts blaming long-line fisheries.

Varied bird life

The two islands are Steeple Jason and its larger neighbour Grand Jason, which lie in the far north-west of the archipelago.

They have been given to the New York-based WCS by their owners, the Judy and Michael Steinhardt Foundation.

The Jasons are the species' stronghold

Half of Steeple Jason's 790 hectares (1,950 acres) is taken up by a colony of around 157,000 breeding pairs of black-browed albatrosses. This is almost one-third of the global population.

There is a smaller colony of 52,700 pairs on Grand Jason, which has an area of 1,380ha (3,410 acres).

The islands are also home to several hundred thousand pairs of rockhopper penguins and several hundred pairs of southern giant petrels.

They are uninhabited nature reserves, but still carry traces of the uses to which they were once put, especially overgrazing by sheep before they were removed in 1968.

On Steeple Jason there are the rusting remains of pots which were once used for rendering down penguins for their oil.

Becky Ingham, of Falklands Conservation, said protecting the seabird colonies was one of the organisation's top priorities, and they were delighted at the link to the WCS.

Insurance against disaster

She said: "The world's albatrosses face increasing pressure due to overfishing and mortality from long-lining.

"Secure and undisturbed breeding places become ever more important if they are to maintain or increase their populations."

Rockhoppers will also benefit

She told BBC News Online: "The gift of the islands is obviously of great significance for the Falklands because of the international recognition it brings.

"It's potentially very significant for the albatrosses. There'd be huge disruption if there were a fire there, for instance - you could lose a vast chunk of the world's breeding population."

There are thought to be about 535,000 black-browed albatrosses, almost 75% of them in the Falklands.

The birds have a wingspan of up to 2.4m (8ft), and lay single eggs in October. They are known to live up to at least 30 years of age.

Other birds on the Jasons include gentoo and Magellanic penguins, thin-billed prions, striated caracaras, tussac birds and black-throated finches.

Images courtesy of Richard White, Seabirds at Sea Team, Falklands Conservation