It is often said that creating a garden pond is one of the most positive things we can do to encourage wildlife. The best of them attract frogs, toads, newts, snakes and other reptiles and amphibians.

Three conservation groups have joined forces to ask us to survey the amphibians and reptiles that have found a home in our gardens.

The British Trust for Ornithology, Froglife and Herpetological Conservation Trust have joined forces to launch the Reptiles and Amphibians in your Garden survey, which is taking place until the end of June.

The survey asks which of the possible inhabitants, the common frogs, common toads, smooth newts, palmate and great crested newts, grass snakes, and smooth snakes, slow worms and common and sand lizards have been seen there since January 2008.

A particular concern is the evidence of disease among these populations and the survey asks for any reports of deaths of a group of five or more frogs at any time since January 2006.

The request for information goes back to the hottest year 2006 as there is a concern that temperature and disease may be linked.

John Baker, of the Herpetological Conservation Trust, said: “This is the largest survey of these species focused on gardens in Britain and it has been designed to complement other studies that are tracking the fate of amphibians and reptiles in the countryside.”

One wildlife gardener who has been keeping records for many years is Tony Rayner, who lives in Cholsey. “We have been doing so since we came here more than 20 years ago,” he said.

He and his wife Ro have a garden containings three ponds, one of which he describes as ‘active’, and as being in the best condition of the three, holding water very well and with interesting plants growing in its margins.

“We used to have a lot of frogs”, he said, “and a lot of toads, which would come quite close to us. But now we don’t see anything like the numbers that we used to see.

“The frogs used to breed here in their hundreds, but they have virtually gone.

“We have just a few common newts, and have had a strong colony of grass snakes.”

He has observed that severe frost has had an impact on frog numbers, but he found that on that occasion the depleted numbers soon built back up again.

Now Mr and Mrs Rayner are biding their time and hoping that their frogs and toads will return naturally to their garden.

Conservation organisations advise that this is the best policy, and frog spawn and toad spawn or adults from elsewhere should not be introduced because of the risk of bringing in diseases or seeds of alien plant species.

This policy will be followed by Pond Conservation, a national charity with its headquarters at Oxford Brookes University, as it promotes its project for the creation of new ponds, the Million Ponds Project.

Its communications manager, Ruth Welters, said: “Ultimately, the aim is to reverse a century of pond loss, ensuring that Britain once again has over one million countryside ponds. A critical element of the project is that these new ponds will have clean water.

“This is because most countryside ponds are now badly damaged by pollution, and evidence shows that pond wildlife is declining across the UK.”

Many ponds once used for watering livestock have been filled in or have disappeared over time.

If people would like to establish a wildlife pond in their own gardens, Pond Conservation suggests that it would be best to start afresh by digging a new one, even if one already exists, and to create there the ideal conditions.

These include filling the pond with collected rainwater, and not tap water. The idea is to make the pond of only a shallow depth, about 50cm is enough.

“It is important to have a really shallow edge, only 1-2cm deep,” said Dr Welters. “Most of the insects will be there, and dragonflies and beetles could fly in.”

The best form of covering for the pond liner is gardening sand, rather than soil, which will bring in unwanted nutrients. Plants such as the rare stoneworts like to colonise bare sand and clay below the water surface.

“If the pond is prepared in this way it won’t become green and slimy,” said Dr Welters. “Sand is nutrient poor and therefore more suitable than soil.”

The pond could have different depths within its area — and if there is space, more than one could be dug in differing situations. All should be sited where they will not be affected by any run-off of surface water, and where streams could in-flow.

To qualify as a ‘clean-pond’, the new garden feature needs to meet three criteria: that it is filled initially with clean water, that it is left to colonise naturally, without artificial introduction of water creatures or plants, and that those which arrive should be left to thrive without undue disturbance.

“New ponds let you start with a clean slate,” said Dr Welters.

“Animals and plants have evolved to live in ponds over many millions of years. The best way to protect pond wildlife today is to create water bodies that mimic the clean wild ponds common in the past.

“This isn’t hard, because natural ponds come in all shapes and sizes and depths and many are tiny and seasonal. The main requirement is clean, unpolluted water.”

The importance of this is emphasised by the fact that around 80 species associated with ponds are considered as under so much threat that they have priority status under the UK’s Biodiversity Action Plan.

Among them are the reed bunting, yellow wagtail, and the song thrush. Breeding song thrushes need dense woody vegetation for nesting cover that is situated close to the damp soils that provide them with the invertebrates on which they feed.

Bat species such as the barbastelle and noctule fly over water as they hunt for their prey, and aquatic insects are an important part of the diets of the soprano pipistrelle, which often forages near freshwater habitats.

Ruth Welters said that water voles could benefit from living near ponds, where they might be less at risk from predators.

Many snails are found now only in very restricted areas, including the mud snail, which lives in pond water low in nutrients or around seepages.

The BTO can be contacted for survey forms on 01842 750050, or via the website www.bto.org.uk Information about the Pond Conservation Million Ponds Project is available on 01865 483249 and at www.pondconservation.org.uk