From The Wall Street Journal:
During the day, as visitors file through the University of Coimbra’s 300-year-old Joanina Library, the creatures remain hidden behind the grand, gilded bookcases.
At night, they come out to protect the books.
They are a group of perhaps a dozen resident bats. As lovers of literal bookworms—they eat the moths and beetles that devour glue and paper—they are also the library’s unwitting conservationists. And their presence is driving Joanina’s staff batty.
The bats are getting too much attention. The librarians want people to know Joanina for its books and the knowledge they contain, not for its flying mammals. Instead of fielding scholarly inquiries about rare, hand-illustrated Bibles or century-old world atlases, staff members find themselves mostly answering questions from visitors about the lives and habits of the bats.
“It pains me,” said Jorge Manuel Neves Justo Alexandre, who has been caretaker of Joanina since 2000. “Here you have all this beauty, this knowledge, and they are asking where the bats poop.”
Mr. Alexandre was recently discussing the issue with Celeste Mateus, a library worker who was vacuuming the main entrance, when a visitor interrupted. “Are the bats behaving?” asked Pinto Almeida, a judge from the Portuguese town of Coriscada.
. . . .
The university—which was named a Unesco World Heritage site five years ago—is partly to blame for the problem. It promotes Joanina’s bats on its website and in booklets, and the gift shop sells pencil covers of a smiling bat holding a candle and reading a book. The university drew around 500,000 visitors last year, more than double the number in 2013, said Joanina deputy director António Maia do Amaral.
The library’s bats are small, often no more than 1 1/2 inches long, from a species called pipistrelle. A second species, called European free-tailed, may be present as well, based on a bat expert’s evaluation of the sounds they made during an inspection years ago.
The creatures are seldom seen during the day, when they mostly sleep behind the shelves. They sometimes fly out at night through cracks in the doors to feast on flies. Mr. Maia do Amaral said that visitors’ best chance to see them is on evenings the library holds classical music concerts.
No one is sure how long bats have been at the library, built in 1728 and furnished with black lacquered shelves, wood carvings and gold brought in from the Portuguese colony of Brazil. The library’s six reading tables are covered every evening with leather shrouds, which shield the wood from corrosive bat droppings and need to be vacuumed regularly. Mr. Maia do Amaral said he found old documents that showed the university imported lengths of leather from Russia in the late 1700s—he suspects for the same purpose.
. . . .
Mr. Maia do Amaral acknowledges that many of the library’s visitors aren’t really interested in those facts. “An old director used to grumble that the bat obsession was offensive to the library’s intellectual nature,” he said.
Still, he appreciates the bats’ help in preservation. “The glue used in old books in particular is made for an insect banquet,” he said, calling the bats his “honorary librarians.”
Link to the rest at The Wall Street Journal and thanks to Patricia for the tip.
PG says the photos of the library in the OP are spectacular. If the WSJ’s paywall won’t let you through, you can do a Google Image search for the Joanina Library