By Giles Wilson BBC News Online, Falklands Islands

Penguins are as synonymous with the Falkland Islands as ravens with the Tower of London. But the mysterious death of thousands of penguins could raise difficult questions for the islanders. When David Pole-Evans spotted whales off the coast of the Falklands in April, it was for him a moment of history. Not since the days of whaling in the 1930s had they been seen from Saunders Island, a 46-square mile outcrop which Mr Pole-Evans farms with his father.

The penguins were just standing round, not looking very fit or healthy

David Pole-Evans

But he spotted something else as well. The rockhopper penguins - one of the four species found on the Falklands - seemed out of sorts.

"They were just standing round, not looking very fit or healthy. You can tell when stock isn't very happy and looking at these penguins, there was something wrong."

It reminded him of 1986 when the penguin population had taken a huge hit for reasons no-one was really able to determine. He feared the same thing was happening again, and informed the island's conservation officials.

Just weeks later, his fears were confirmed. Thousands of penguins were dead on the beach, in the water, or being picked off by the striated caracara, one of the world's rarest birds of prey. He estimates a death toll so far of up to 9,000 rockhoppers and up to 1,000 of another species, gentoos.

Isolated problem

Officials from Falklands Conservation say they are mystified, although they are relieved that similar deaths are not happening in other places around the islands.

Will satellite tracking help solve the mystery?

Some post mortem examinations have been carried out, but wider conclusions are not easy to draw. Nick Huin, the organisation's scientific officer, says: "We're worried, because we don't know exactly why it's been happening."

In a bid to learn more about the habits of the penguins, satellite tracking devices have been fitted to 10 birds to allow researchers to track their movements over hundreds of miles across the oceans in real time via the net.

But environmental researcher Mike Bingham, who photographed and documented the dead birds, is convinced it's a simple matter that the birds have died from starvation.

Nick Huin: "We're worried"

When penguins moult, they must come ashore because they are no longer waterproof. But to be able to stay on shore long enough to moult means they must fatten themselves up beforehand.

This year, as in 1986, they came to dry land much later than normal, perhaps indicating they were having trouble finding their diet of crustaceans and small fish.

The squid fishing industry, on which the new-found wealth of the Falkland Islands is based, has also had a bad year with low catches of the ilex squid which is exported to the Far East.

Over-fished, underfed

The Falklands Island Government is negotiating with the fishing companies about discounts for next year's fishing licences to compensate for the bad year.

There's no question whatever that the penguins have starved

Mike Bingham

It could be that whatever has caused the low squid harvest - complex Atlantic currents, for example - could be having an impact somehow on the penguins. But Mike Bingham blames fishing as well.

"I think the two things combine. I think we've got a natural cycle of a low abundance of squid which both the penguins and the fishing industry are relying on. Obviously if the fishing industry is taking out a large number during bad years, it exacerbates the problem.

"I'm sure the government will give different reasons, but there's no question whatever that the penguins have starved."

Eco-tourism boom

A conflict between fishing and tourism is just what the Islanders are keen to avoid. Fishing licences bring the government �22m a year, and are the major reason the islands have become independent of any subsidy from London (excluding the �70m spent each year on the Islands' military presence).

Sea lions are among the attractions

But at the same time, an increase in tourism is one of the great hopes of the islands, which want to win a reputation for being clean and green, and which boast of their 347 types of plants and of being the breeding grounds for 70 different animal species.

Tony Pole-Evans himself runs three self-catering houses for people wanting to get close to the bird and sea life.

The islands government is spending �1.3m a year on environmental research, and believes its fishing is the best managed in the world.

Nick Huin says the situation with the rockhoppers will not go unmonitored. Breeding pairs will be studied at the start of the Falklands summer, and then the chicks will be observed in February.

"I don't think we'll fully know what's happened until next summer," he says.