It’s National Library Week, so let’s pay a visit to a couple very unusual libraries where some of those who help protect the books are bats.

Both libraries are in Portugal.

One is the Joanina Library on the campus of the University of Coimbra.

The other library is at the National Palace of Mafra.

Both buildings are centuries old.

They’re both home to some extremely rare old volumes, and they both have bat colonies.

While the librarians probably could take steps to remove the bats, that’s probably not on the table.

That’s because the bats are actually performing a pretty useful service.

When they fly around at night, they eat up insects that might try to eat and therefore damage some of the libraries’ books.

But for those who might want to visit the two libraries in person and thank the bat colonies for their tireless service on behalf of book lovers everywhere, take note.

The libraries are closed at night, meaning the bats are mostly active when people aren’t around.

Those who know the libraries say you can sometimes spot them around twilight, if you know where to stand.

You can also sometimes hear them late in the day, or if it’s a particularly cloudy and rainy day.

Even if you can’t spot them, you can definitely see the effects of their presence.

The librarians at the University of Coimbra put traditional coverings out to protect each table from overnight bat droppings.

And each morning, they have to clean the floors.

The Brautigan Library in Vancouver, Washington is a physical and online library that collects unpublished manuscripts.

It’s named for author Richard Brautigan, who wrote a book that envisioned a space for “the unwanted, the lyrical and haunted volumes of American writing.”

And now there is one!

These Portuguese Libraries Are Infested With Bats — and They Like It That Way (Travel + Leisure via Yahoo!)

The Brautigan Library (Futility Closet)

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