Stashed inside the Biblioteca Joanina at the University of Coimbra, Portugal, are more than 60,000 books, many of which are first or historical editions dating back hundreds of years. Preserving such precious volumes demands care, attention, and, in this case, bats. Every night, colonies of bats emerge from behind the towering bookshelves, swooping across the 18th-century library in search of the beetles and moths that would otherwise chew up manuscript pages.
At first, it may strike some as unusual, but these bats serve as an effective source of pest control, and, according to the library, have lived within its 6-foot stone walls since at least the 19th century. It was around this time that Biblioteca Joanina purchased large leather sheets from Russia to protect its desks from bat droppings throughout the night. Even today, librarians still employ this method, unfurling the sheets over the furniture and, come morning, dusting away all the droppings. The library’s windows are also left open, allowing bats to flutter outside and into the palace’s gardens to drink water.
Given their nocturnal habits, these bats are challenging to encounter while the library is open during the day. That said, Joanina librarians have noted that, late in the afternoon on rainy days, some bats may begin to stir, emitting chirps and squawks that almost resemble singing. Beyond this, the library offers evening concerts, which typically occur right around a bat’s dinnertime.
Biblioteca Joanina is only one of two libraries in the world that houses bats alongside its books. Just north of Lisbon is the 300-year-old Library at the National Palace of Marfa, in which another colony of bats resides. According to Hugo Rebelo, a bat biologist at the University of Porto, these colonies are mostly composed of grey long-eared bats and some serotine bats. At Biblioteca Joanina, there are two types of bat colonies as well: European free-tailed bats and soprano pipistrelles.
Though its bat colonies are certainly a draw, Biblioteca Joanina is an evocative example of Baroque architecture as Portugal’s oldest library. The structure spans elaborate decor, ornate balconies, two-story book shelves, and dramatic, gilded arches separating rooms. Its monumental façade also combines the simplicity of white and earthy tones alongside decorative pillars that crown the entrance.
To learn more about Biblioteca Joanina, visit the University of Coimbra website.
Biblioteca Joanina in Portugal is only one of two libraries in the world that houses bats alongside its books.
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These bats emerge at night and eat up the insects that would otherwise feast on the library’s rare manuscripts.
European free-tailed bat, one of the species found within the library. (Photo: Emanuel Yellin, via Wikimedia Commons, CC 3.0)
Soprano pipistrelles, one of the species found within the library. (Photo: Evgeniy Yakhontov, via Wikimedia Commons, CC 3.0)
Sources: These Portuguese Libraries Are Infested With Bats—and They Like It That Way; In This Beautiful Library, Bats Guard the Books
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