The mystery killer in the garden pond: Our frogs are dying and experts fear the problem may herald even more serious environmental concerns, says Nicholas Roe

GAIL HUGGETT meets us at the front door of her home in Reigate, Surrey, and leads the way into the back garden saying: 'You think they're alive at first, but when you touch them they don't move. I've been burying them in the compost heap.' She is talking about an environmental tragedy of possibly worldwide significance, the evidence for which, she tells us, is waiting in a bucket at the bottom of the garden.

It is raining. The garden is small. Halfway along the path we discover two tiny ponds, the kind found outside many homes, and between them stands a green plastic pail containing an inch or so of water.

Peering in, we see the plump bodies of six dead frogs. They are stretched out in sad detail, fingers splayed like those of little children. It is a stark and affecting sight. It is also only a minor part of the developing drama we have come to witness.

In the past three weeks Mrs Huggett has picked up a total of 95 frog corpses in her garden. Two doors along, Barbara Haysom has gathered 78. Yet another neighbour has lost his entire frog population; dozens upon dozens of corpses litter his lawn.

Tom Langton, an ecologist who is investigating this bizarre phenomenon, listens to these details, then borrows a key from Mrs Huggett and goes next door where the owners are away on holiday. Walking into the back garden we find yet more frog bodies, including one sitting right in the middle of a picnic table, looking wizened, dried out, frightening.

The really worrying fact, however, is that this road is simply one of many across the country where outbreaks of unexplained frog deaths have been taking place. In the past four months, researchers have noted 250 cases, mostly concentrated in garden ponds in southern England, but others appearing throughout Britain.

The worst has involved 500 corpses on a single site in Buckinghamshire. Reports of more than 100 bodies in a pond are not unusual. All the deaths have no known cause. Some of the dead amphibians have a reddening of the skin, leading to speculation that they were suffering from an infection known as 'red leg', which involves bacteriological invasion. Not all the dead frogs are coloured, however, which points to the deaths as being part of a wider problem.

Mrs Huggett describes her own experience: 'We put the two ponds in 10 and 11 years ago and the frogs came on their own. The first year I didn't get any spawn. Then the second year it was one blob, and since then it has built up steadily.

'My neighbour came around the day after we got back from holiday and said she had found a lot of dead frogs. I went down to my own ponds and the big one smelt awful. I looked next day and that is when I found all those dead frogs. The water had gone putrid, so I lost all my goldfish as well. When I looked round there were all these other bodies sitting there, dried up, like the corpses of the people at Pompeii.'

Stories elsewhere are similar. Animal experts are wary about what to make of the phenomenon until a series of post-mortems and environmental tests (partly funded by the Royal Society for the Prevention of Cruelty to Animals) has been completed.

Meanwhile, Andrew Cunningham, veterinary pathologist at the Institute of Zoology at London Zoo, who is co-ordinating the research, says: 'There is speculation that amphibians are the most vulnerable type of animal to environmental pollution because they have a very sensitive, permeable skin and are semi-aquatic, so they get the worst of both worlds. It could be that they are an indicator - like a canary in a mine.'

The first hint of a problem emerged in 1986, although few spotted it. Mr Langton, who runs Herpetofauna Consultants International, a company specialising in advising government and industry on the care of amphibians, was asked by an environmental charity to study frog numbers in London.

He discovered a vast spread of colonies thriving in garden ponds, which had been established as fashionable gestures of environmental concern. Less pleasantly, he bumped into half a dozen strange stories of mass deaths. He published details of these in a paragraph or two in a newsletter.

Time passed and frogs continued to die in growing numbers.

'In 1990 and 1991, I was aware of people still reporting the phenomenon and it seemed to be growing,' Mr Langton says. 'There were now dozens of reports a year and I was approached by Andrew Cunningham and Peter Bennett at the Institute of Zoology. We had a meeting and decided to collaborate.'

Mr Cunningham had been receiving a growing number of letters on exactly the same problem. He says: 'Nobody has really done a study of what kills frogs in this country, so we don't know what background of disease there is. It is the same for most wildlife.'

Together with Mr Langton and Dr Bennett, a research fellow at the institute, he organised a research project and in May this year began appealing for evidence of sudden, unexplained frog deaths. Replies flooded in with disturbing speed.

'I have had people in tears on the telephone,' Mr Langton says. 'There have never been so many deaths reported in such a short time. They could be talking about their children.'

A 60-point questionnaire reveals exactly how many areas of possible concern exist in an ordinary garden: the use of pesticides, for instance; the way ponds are topped up with chemically treated tap water; and the health of other animals or plants which share the same environment.

Ten sites are being studied in depth, with soil and water tests, and post-mortems are being done on fresh corpses: frogs from both Mrs Huggett's and Mrs Haysom's gardens have been taken for examination. It is a grisly business.

Twenty-five post-mortems have been carried out so far, and conclusions will be announced between now and the end of the project next May.

Meanwhile, what can be said about this strange, distressing outbreak? Three things. The first is that it is possible, although unlikely, that there is no link between the deaths. But if a common cause does emerge then all frogs may be under threat. If that is the case, it will be interesting to see how a nation which threw up its hands in horror when seals died on distant beaches will react when a disaster takes place out on its own patio.

Second, as Mr Langton points out: 'The frog is an incredibly important animal. Anything affecting frog numbers can possibly have a further impact on other animals.' Badgers, snakes, birds, foxes and many other creatures feed on frogs; nobody can say what will happen if these creatures lose that food source.

Finally, there is the worrying possibility that the phenomenon is part of a much wider problem. Evidence of a decline in amphibian populations has been emerging recently in many parts of the world. An entire species of frog has become extinct in Tasmania.

The Species Survival Commission of the International Union for the Conservation of Nature, a non-governmental advisory body, last year set up a task force based in the US to monitor the trend. It may be that they find a single cause for the growing number of deaths. It may also be - less dramatically, but more importantly - that Britain turns out to share a problem in which pollution, construction, waste and general disregard for the environment are combining to wipe out our most sensitive creatures.

Either way, the analogy of the canary in the mine becomes that much more alarming. The one comfort is the ironic fact that by bringing nature into our back gardens - by putting in neat little ponds, for example - we may have done ourselves the favour of installing the equivalent of an early warning system.

Then again, beyond the final full-stop lies another consideration entirely. Mrs Haysom says she loves having dinner outdoors on a summer evening listening to the frogs call. Mrs Huggett says: 'I love frogs. If they go completely, I will be terribly sad.'

Reports of unusual frog deaths should be sent to: Frog Mortality Project, PO Box 1, Halesworth, Suffolk IP19 BAW.

(Photographs omitted)