Hidden sensors used to snare bird criminals: Oliver Gillie looks at the electronic equipment that is helping to protect vulnerable species

BIRDS vulnerable to wildlife crime are being protected by remote surveillance devices this year, in the hope of catching egg thieves and other criminals who destroy them and their eggs.

Cameras operated automatically by infra-red beams or vibration sensors have been buried by the Royal Society for the Protection of Birds on remote moorland to provide a continuous watch on vulnerable nests, particularly those of hen harriers and red kites, two of Britain's rarest birds of prey.

Cameras have also been used to monitor rare wading birds which are so vulnerable that the RSPB is not prepared to say what or where they are.

The RSPB will prosecute anyone found disturbing birds if they get photographic evidence, Duncan McNiven, investigations officer for the RSPB, said. 'This method of protection is still in its infancy and we are finding the best way of using it. The best way to stop people disturbing birds is to catch them and bring a prosecution.'

The new generation of surveillance devices tried out this summer consist of a camera triggered by the interruption of an infra- red beam or by the detection of vibration caused by footsteps. These devices are more economical on film usage than the old Super-8 movie cameras used in the past, and so can be left unmanned for much longer.

However, the infra-red trigger may be activated by the birds or other wildlife. The vibration trigger can detect the difference between a man and a sheep but aeroplanes may trigger it.

'We are trying to stay one jump ahead of the egg collectors,' Mr McNiven said. 'Our priority has been birds of prey because they have so many enemies. There are at least 300 egg collectors in the country and they are a particular nuisance because the rarer a bird, the more they want to collect the eggs.'

The RSPB is having teething troubles with the technology. A camera placed on land owned by North West Water in the Forest of Bowland broke down while surveying a hen harrier nest, and the next day four eggs were stolen from the nest.

In the first seven months of this year, the RSPB received more than 700 reports of wildlife crime. Birds of prey have suffered heavily from persecution, the society said yesterday. The tally is 26 peregrine falcon nests robbed and eight adults killed; two hen harriers shot or poisoned and 11 nests raided or destroyed; 21 buzzards killed; four red kites poisoned; two golden eagles killed; one sea eagle shot; three goshawks shot; and five sparrowhawks shot or trapped.