Bats may need their own version of the safe cross code to navigate across busy roads, according to research presented in Galway this week.
The tiny mammals have difficulty flying safely across roads, so their habitat is increasingly restricted in our modern landscape, delegates were told at the 10th European Bat research symposium at NUI Galway.
Bats usually follow hedgerows to find their way from one foraging ground to another, Dr Fabio Bontadina from the Department of Conservation Biology at the University of Berne said yesterday. When these are bisected by roads, the bats tend to fly too close to the ground and are often killed by traffic.
"Green bridges" could provide an answer, Dr Bontadina suggested. These bridges are covered in plants to mimic hedgerows and could mark out a "flight path".
"Bats have a problem reaching resources in this fragmented landscape. We were interested in how plants in containers could be used to link hedgerows from one side of the road to the other."
The researchers examined whether lesser horseshoe bats could learn to follow a row of plants leading to their feeding area. Four hundred containers of plants were lined up to form a hedgerow in the bats' natural habitat and Dr Bontadina and his colleagues used infrared video techniques to track their flight path.
Within six weeks, up to 20 per cent of the bats had started to use the "hedgerow" for navigation. "This extended their foraging time and range," said Dr Bontadina. "These bats, each weighing only 5 grams, were travelling between 2 and 4 km a night. The lesser horseshoe bat is endangered in Ireland and the rest of Europe. Extending foraging time like this could help improve their survival."
Dr Bontadina is working with motorway companies in Germany to test whether "green bridges" could help guide bats safely over busy high speed roads. If successful, this strategy could help "to save the remaining colonies of these endangered species."
Prof Jiri Gaisler, from Masaryk University in the Czech Republic, highlighted the importance of monitoring bat populations. Prof Gaisler has been observing bat populations since 1955.
"Bats are very sensitive to negative environmental changes. Thirty or 40 years ago, there were very few lesser horseshoe bats in Ireland and the rest of Europe, due to the impact of insecticides and loss of hibernation areas," Prof Gaisler said.
"While the numbers are now starting to recover, we must continue the improvements in nature conservation seen in recent years. Constructing new hedgerows and protecting the existing hedgerows is very important."