Guy Fawkes Night is not the only threat to the survival of the lovable hedgehog as surveys show their number has halved in some areas, writes ELIZABETH EDWARDS

Where have all the hedgehogs gone? Fewer sightings over several summers, including in Oxfordshire, have led the British Hedgehog Preservation Society and the People's Trust for Endangered Species to ask these questions in a national survey.

At the beginning of this year, BHPS members members were sent a postcard for its HogWatch survey, asking whether hedgehogs were seen and where.

This has been followed by a more detailed survey to enable an accurate mapping of the hedgehog population to be recorded, including grid references, together with the type of habitat.

The two charities are funding the project, which is being co-ordinated by Dr Paul Bright, of Royal Holloway, University of London.

Observers are also being asked whether they think that hedgehogs appear to be more or less common in their own area than they were five years ago.

Anecdotal evidence has pointed to the absence of hedgehogs from gardens and the countryside. Results from the PTES Mammals on Roads surveys is showing evidence that in rural England, and probably in Wales, populations are declining rapidly. This survey, however, is only of live hedgehogs and not of road accident casualties.

In Oxfordshire, the decline appears to be between ten and 20 per cent, but in other areas it is much greater, as much as 50 per cent in East Anglia.

Hedgehogs are not found everywhere. Where conditions in the countryside appear unsuitable for them they seem to be clustered around villages. In some regions, they are clearly found in more places than others.

One of the reasons for the decline is the climactic changes of long dry periods and short, heavy downfalls of rain. The resulting lower moisture levels in the ground mean that the invertebrates, which are the hedgehogs' staple diet, cannot flourish.

"It is vital to know where hedgehogs are still present and determine why their numbers appear to be falling," said Dr Bright. "This will not only help us to safeguard an endearing favourite of the British garden, but also many other species with similar needs.

"Letting us know if you haven't seen hedgehogs is just as important as letting us know that you have. Hedgehogs have been around for 20 million years - we want to ensure that they will be around in the next century."

So far there have already been more than 16,000 responses to the survey, but the more people who take part, the more complete the picture. Anybody who would like to add the information they can offer can contact the BHPS on 01584 890801 or PTES on 0207 498 4533, or on-line at the www.HogWatch.org uk website.

The BHPS is concerned with hedgehog welfare and has a network of carers who can either take in sick and injured hedgehogs or give advice on how they should be cared for. Contact details are available on 01584 890801.

At this time of year, the public is reminded of the danger to hedgehogs and other creatures who may be enticed by piles of leaves and garden material made ready for Guy Fawkes Night bonfires.

The society's carers have had to deal with very many horrific injuries after bonfires were carelessly lit without having been checked for animals.

The best way to prevent this dangers is not to build a bonfire in advance. If it has been standing for a few days, it should be thoroughly taken apart, not with sharp tools such as spades and forks, and the area checked for sleeping creatures. Ideally, the bonfire should be completely dismantled and moved to another area of clear ground just before lighting.

Any hedgehogs found should be moved, together with any surrounding material, to a safe place where they can resume their hibernation in peace. Another problem approaching is hedgehogs which have not yet built up sufficient fat reserves to see them through their winter sleep. Putting out food, such as tinned cat or dog food (other than fish varieties) and a bowl of water will help then, but any weighing less than about 500g should be taken indoors and kept warm until they have put on sufficient weight. Bread and milk should not be given.

Hedgehogs face other problems in the gardens. Gardeners should be aware when raking up leaves, using strimmers or mowing long grass, or turning over compost heaps, of the possibility of creatures being hidden there.

As hedgehogs often like to drink from a pond, this should have sloping sides so that if one should fall in, it has a means of climbing out.

Not least among the dangers is road traffic and the BHPS sells a device that could be effective in averting accidents - an ultrasonic whistle which attaches to the front of a vehicle. It is airflow-activated and emits a high-frequency whistle which, although inaudible to the human ear, alerts an animal when a vehicle is approaching. Users have found it to be effective. The cost is £7.50, plus £2.50 postage.

After a five-year campaign, the British Hedgehog Preservation Society has successfully persuaded McDonald's to change the packaging of their McFlurry ice cream dessert which has been the cause of many hedgehog deaths.

The hedgehogs have been known to become trapped in the discarded cartons. The society had reports of hedgehogs which had been released by kindly passers-by, and of others that were found dead, but says it will never be known how many others suffered.

The new McFlurry lid has a smaller aperture, and even if the carton is discarded with the lid still attached, it is too small for a hedgehog to push its head inside.

McDonald's said that in consultation with the BHPS it has undertaken significant research and testing to develop this new packaging. The company continues to display anti-litter patrols of its own, said a spokesman.

Fay Vass, chief executive of the BHPS, said: "This is excellent news. We have been in touch with McDonald's about this problem for over five years and we are delighted that they have at last solved the problem. Thanks to public support for our campaign, every McDonald's restaurant in the UK will be using the new lids on their McFlurry cups and many hedgehog lives will be saved."