Emily Chan
Since the late 18th century, small colonies of bats have guarded the books in the Joanina Library at the University of Coimbra in central Portugal. The library contains 60,000 books that are all hundreds of years old.
When the library was built around 300 years ago, six-foot stone walls were erected to protect the texts from the elements. But the real heroes are the bats.
At night, a bunch of bats silently swoop through the stacks, picking off pests that threaten to eat away at the fragile books. The bats consume flies, gnats, and other insects before flying out of the windows in search of water.
The library’s records show that the bats were residents since at least the late 18th century. That was when large leather sheets from Russia were purchased to protect the desks and tables from the bats’ scat.
To this day, a fabric made of animal skin imported from Russia is still used to cover the original 18th-century tables.
Library employees clean the scat every morning and dust frequently throughout the day, although the books are now kept behind wire mesh.
They leave the bats alone and let them do their jobs. Two types of bats have been identified at the library: European free-tailed bats and soprano pipistrelles.
In 2015, the Joanina’s massive wooden doors were replaced. The carpenters left the original gaps the bats used to exit the building.
Some speculate that they were introduced to the library on purpose, but those who currently work with them think they made their way in on their own.
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