Sound step to conservation

In the important matter of wildlife conservation, making use of the best tools is essential and a new 'tool' has come the way of work with bats. The Northmoor Trust at Little Wittenham has recently taken delivery of the Anabat, a piece of surveying equipment designed to improve data on local bat populations and so aid their protection in the Thames Valley.

The device can differentiate between the sounds of different species and the nature of their calls.

"It is a brilliant piece of equipment," said Mike Rogers, the Northmoor Trust's ornithologist, who also carried out survey work on bats. "It will give us a much better means of detection," he said. "You can go out and use it like a normal bat detector and point it directly where it is thought the bats may be.

"All the sounds are then recorded on to a flash card. This is put into a computer and you can find out exactly which species have been calling. Each bat gives a different sound and each makes calls that are 'hunting' calls or more social ones.

"The equipment will also tell us whether the sounds have been echo-location, or just the bats nattering to one another. Bats have a cheeping, social call, more in the human range of hearing, but the echo-location sound is of much higher frequency - some Horseshoe bats have a range as high as 100 kilohertz or more."

Bats are said to be able to make as many as 27 different sounds. In using their sixth sense of echo-location, they make high-pitched sounds bounce back, enabling them to find their way around and to catch prey on the wing.

This sense is a very highly developed one which is enhanced by the long ears and the shape of the face of the bat. Having used it to track their flying insect prey, they catch these between their hind legs and in one movement scoop them into their mouths.

All British bats are insect-eaters. Regular monitoring of bats and insect numbers is therefore of great importance.

At a recent conference, Mike met fellow conservationists, who reported on their own successes in using the Anabat.

"They said that they have been finding it invaluable. It takes a lot of the guesswork out, and is most valuable in providing information."

On a recent bat walk at Little Wittenham, Mike and David Endacott, of the Oxfordshire Bat Group, took a party of interested visitors around the grounds at dusk. On their walk they visited the maternity roost, where the young bats are now maturing.

At the last count, this roost housed some 207 bats, mostly common pipistrelles, or soprano pipistrelles - those with the particularly high-frequency sounds - and a small number of brown, long-eared bats.

The young are generally born towards the end of June and continue to be fed by their mothers until they have perfected their own flight and echo-location skills.

The Bat Conservation Trust also highlights the importance of monitoring, across a range of habitats, in order to track changes. The data collected has already mapped changes in population and is helping to indicate whether these are long-term trends.

In Britain there are 17 native species. Because of the decline over the past 60 years, all are protected by law and it is strictly illegal to harm a bat or to interfere with a roost.

From next May, the trust, in partnership with Oxfordshire Bat Group, will begin its next programme of monitoring, which will continue each year between May and September.

The trust is aiming to recruit volunteers who will be trained to use the requipment - groups of around ten people will have the opportunity to join the bat survey co-ordinator fortnightly.

Local special interest groups will be invited to take part and to make use of the equipment themselves, should they wish to undertake surveys in their own localities. The data will add to the information gathered throughout Oxfordshire.

Mike is looking forward to working on the new project.

"Ever since bats started to use the nest boxes on our site, I have been fascinated by these little creatures. Little is known about bats but with the help of local volunteers and with the new equipment, we will begin to learn a lot more."

The Anabat is funded by the John Spedan Lewis Foundation, South Oxfordshire District Council, Natural England, and the Thames Valley Environmental Record Centre.

Another way in which the bats in the trust's grounds can be supported is by sponsorship of its bat boxes. These are similar to the bird boxes which, Mike found, the bats were using.

"The boxes are very strongly made, so no doubt the bats feel safe in there, also there is a nice rough lining on which they can take hold."

The trust is placing ten boxes around its estate and sponsors can 'Rent a Roost' at £20.

Details of training in bat monitoring and the bat and other wildlife adoption schemes are available from the Northmoor Trust on 10865 407792. A sponsorship order form can be found on the website www.northmoortrust.co.uk