The worker was getting ready to open the library’s doors when she saw the owl early on Monday morning. She was scared to touch it but colleagues stepped in to help rescue the bird, which staff believe had been stuck in the library over the weekend.
Senior librarian Fiona Myles said the flying visit from the distinctive bird has lifted the spirits of the staff.
"First we noticed the mess. Then we spotted the owl flitting about when she came in on Monday morning. What a surprise. We get loads of pigeons. But a barn owl in the middle of the city, in a library. We do have lots of trees nearby in Greyfriars and the Meadows."
She continued: "The poor wee thing had got caught in the wrought iron window bars and must have been trying to get out when we found it. Our colleague Greg scooped it up gently in overalls and let it out. The art and design library is really high up and owls do like to roost up high so that's maybe how it went up there. And of course, we've been keeping the windows open to let the air get about, because of Covid-19 safety."
She said cleaners suspected the bird had been trapped in the library since Friday.
"We saw signs that it had been here a while. Well, they are known to be wise birds. At least it had plenty of books. It got away fine, and really cheered everybody up no end.
"We've had lots of jokes going around about how it must have been owl post delivering a letter for Harry Potter. It is an old building, very Hogwarts. So I suppose it's fair to say now we are open for business for people and for owls" she laughed.
Ms Myles said they might even consider adopting an owl as their mascot as she urged Edinburgh residents to come in and use the library, which opened part-time on October 6.
"We hope to see people coming in now that we are open again, please remember to book online," she added.