CEC launches the bat sledge

The bat sledge is not a winter toy for Robin and his boss the coped crusader, but a new tool developed by CEC for undertaking bat surveys in mineshafts. Phil Hills reports.

CEC was invited by Kerrier District Council to undertake a series of surveys of disused mineshafts for a forthcoming capping programme. If bats were present in the shafts then this would have an impact on the way the works could be carried out.

Health and Safety requirements prevented our surveyors from inspecting the shafts by rope and torch and a new technique was required to provide information on whether the shafts were used by bats for roosting.

The sledge is the brainchild of project manager Caroline Arkley who worked closely with local engineer Peter Davey on its development. It consists of a wooden frame with curved runners, designed to allow it to be lowered down and hauled up without snagging on vegetation and other obstructions (many shafts have been used as an informal waste disposal system for many years). The sledge is held in place by steel wires attached to a winch once in place.

The detection system includes a Petterson D240X bat detector which can detect the calls of different species of bats at the same time, linked to a Sony Walkman Professional tape recorder via a sound activated relay switch. The power system was also expanded to contain enough rechargeable batteries to allow the system to run for 4-5 days at a time. All the electronic components are housed within a waterproof box.

The bat sledge has proved to be a success and the detection equipment can be used separately from the sledge in buildings and other structures. CEC is now looking forward to using the system in other locations.

Phil Hills
Consultancy Manager
(CEC - Cornwall Environmental Consultants - is the Trust's consultancy. www.cec.gb.com)