Rare bats hanging around old ArcelorMittal mines

Some of Luxembourg's biggest and rarest bats are scouring the night skies near Bascharage looking for bugs to eat.

And the Grand Duchy's largest industrial company is claiming credit for helping the winged mammals about the size of a blackbird or small owl sleep away the cold season in peace. Steel-maker ArcelorMittal was long required to keep curious humans

out of its former iron mines in southern Luxembourg that closed 50 years ago. Mine openings used to be blocked by steel doors with two narrow slots for ventilation.

But almost four years ago, ArcelorMittal responded to requests by state naturalists, replacing the doors with metal grates, which have crisscrossing horizontal and vertical metal bars - much like barriers at medieval fortress entrances.

The grates allowed bats easier access to the dark and quiet stone

walls inside, which bats grip with their hind legs as they hang for months waiting for winter to pass and their food source to reappear. A check of the mines in the "Giele Botter" section of former ArcelorMittal mine-turned-nature-preserve between Bascharage and Petange found they now offer sanctuary for five species of bats, said Jan Herr, site coordinator for the country's Nature and Forestry Administration. That included the rare greater horseshoe bat. "The tunnel at Giele Botter is not special in the sense that this species has been located in various other old drift entries in the region," Herr told Luxembourg Times in an email. "But it was nice to see that the [in this case voluntary] opening of a so-far inaccessible entry by [ArcelorMittal] so quickly produced positive results."

That makes it more likely that the grates will be used at still-unsecured mine tunnels, which Herr emphasised are dangerous to enter.