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BATS that go swimming and voles that fly. It sounds like The Wind in the
Willows gone mad. But that’s the mystery which confronted
researchers tracking mammals in the English countryside.

Katie Parsons of Bristol University was following Daubenton’s bats tagged
with radio transmitters along the Kennet and Avon Canal in Somerset. “They fly
swiftly over a stretch of water, taking insects from the surface with their
feet,” she says. “But one night the signals showed a bat moving at water level,
very slowly. And it was gradually joined by others.”

Researchers from Oxford University’s Wildlife Conservation Research Unit also
faced a similar enigma. They were out monitoring relocated water voles on the
same stretch of water when their equipment suddenly revealed a number of voles
flying over hedges and trees at speeds up to 10 kilometres an hour.

A chance meeting solved the mystery. Parsons got talking to an undergraduate
who told her about the Oxford group. By coincidence both teams had been using
tags that broadcast on the same frequencies. The bat hunters had been following
voles and the vole experts tracking bats. “I unwittingly started following
Ratties rather than Batties,” Parsons says.

“We discussed the possibilities of having a central register for wildlife
transmitters so that this kind of thing doesn’t happen again,” she says. “The
chances of two groups working in the same area at the same time with the same
frequencies are very small but it’s a shock when it happens.”

Britain’s Mammal Society says it may now publish the radio frequencies
researchers plan to use on its annual list of current projects, to avoid the
confusion happening again.