The university that has bats ‘for hire’ to protect its centenary books from woodworm

The sun sets in Coimbra and an usher approaches the door of the gigantic rococo parallelepiped in the courtyard of the Faculty of Law. He flips the closed sign over and turns the latch. Inside the building, the rest of the workers they unwrap huge old leather covers and place them on the shelves, tables and furniture. They open the windows, set the alarms and go home.

The next morning, before the Joanine Library with its 70,000 books (many of them from before 1800) open its doors, the workers will return to the building, remove the covers and collect excrement from the floor. Since at least the 19th century, the well-being of the library has depended on a delicate balance between culture and nature: every night, two colonies of bats roam the baroque rooms of the Joanina feeding on dozens of types of “bibliophagous” insects.

The delicate balance between nature and technology

According to the Lisbon researcher Jorge Palmeirim, who has spent a lot of time studying the colony, each bat can catch half a thousand insects in a single night that fly between the specimens. It is not enough to feed themselves, that is why they go outside; but they always come back. This has been one of the keys to the excellent conservation of manuscripts, despite the fact that the complex architecture of the early 18th century leaves hundreds of pathways for insects to sneak in.

“We don’t know how many there are,” explained Antonio Eugénio Maia do Amaral, the director of the library to the Hoy newspaper. “They are two colonies, of few individuals, quite small if we pay attention to the sounds that we have managed to record during the night. We imagine that the bats they have lived in the Biblioteca Joanina at least since the end of the 18th century. [Y lo sabemos porque] At that time, purchases of leather table covers began to appear among the current expenses of the institution, which are still used at night with the aim of protecting them from bat waste”

This is how for two centuries, threats as serious as woodworm (Nicobium castaneum) or silverfish (Lepisma saccharina) have been able to keep at bay. Unfortunately, with the growth of the collection (and the addition in recent decades of two underground floors of deposits and work rooms) they have meant that the colonies are not able to protect the priceless heritage from the library.

For this reason, in 2017, Joanina was forced to acquire an anoxia chamber where the books would be deposited for periodic disinsection. Yet the librarians continue to care for the colonies, protecting the delicate balance that has sustained the library for 200 years. This looks more and more like the picture of the future: a place where technology and nature work to build a better world.

Imagen | Nils Bouillard