Owls "nailed to the walls" of Breton farms

One more item gleaned from The Phantom of the Opera (a pretty good book, but not an addition to this blog's category of recommended books).

I was startled to encounter (on pg 144 of my paperback copy) this sentence:

"If we really saw Erik, what I ought to have done was to nail him to Apollo's lyre, just as we nail the owls to the walls of our Breton farms; and there would have been no more question of him."

The reference to Apollo's lyre is to an ornament on the roof of the opera house.  My puzzlement is to the indication that owls were once (19th century, apparently) nailed to farm walls.  I would think most farmers would consider owls to be beneficial in terms of rodent control, so that act would not be appropriate as a triumph over a pest.  Was it perhaps done on an outside wall rather than indoors, to frighten away other granivores (?birds)?

This blog has readers in Brittany.  Perhaps one of you could inquire of an elderly grandparent...

Addendum:  A tip of the blogging hat to reader Abie, who has found what appears to be the explanation (Google-translated from Chouette effraie):

The Barn is the basis of many legends and ghost stories. Indeed, by its hiss, screeches, its ghostly flight and cavalcades in the attic which serves as a cottage, lent credence to a spectral presence. In the Middle Ages the owl was the symbol of heresy . It thus appears about 40 times in the works of Hieronymus Bosch which in Temptation of St. Anthony (it is painted on the character's head after St. Anthony). The bad reputation of the "white lady" has earned him nailed to the doors of the barns where she lived, a practice that was supposed to protect thunderstorms, chase disease, ward off bad luck and scare other owls. This bad reputation is evidenced by Buffon in 1780 who wrote about the Barn:

"It grows sour different sounds all so unpleasant that this, together with the idea of the vicinity of cemeteries and churches, and even in the dark of night, inspires horror and fear to children, women, and even men subject to the same prejudices and who believe in ghosts, sorcerers, soothsayers to: they look like the funeral frightens bird, the messenger of death; they believe that when it is attached to a house, and that she sounds a different voice of its common cry is to call someone at the cemetery " .