Magnus Robb, 43, formerly from Edinburgh, and his team made their discovery in Oman in the Middle East.
The species, completely new to science, is a little bigger than the tawny owl and has been named the Omani Owl.
Tracked down in a remote mountain region of Oman, the owl was first noticed in March this year when it called while researchers were making sound recordings of another species.
Mr Robb, a sound-recordist and author, had not heard anything like it before.
He said: "I was recording a species I know well, when I noticed some faint owl-like hooting in the background with a rhythm I had never heard before.
"My colleague Rene Pop and I tried to find the bird again the next night, but it was only on the last night of our trip that we heard it again. We had to leave for the airport with the unseen owl hooting up on a cliff."
Mr Robb returned a month later with colleague Arnoud B van den Berg.
Mr Robb continued: "Tracking it down again wasn't easy. This owl inhabits vertical terrain and its voice is difficult to hear. Worse still, in April the bird was virtually silent. Eventually we heard one. What a relief to actually glimpse it perched on a rock, confirming that this was indeed an owl and looked like nothing we had seen before."
In May and July the team made two more research trips to look for new individuals, gather photographs and sound recordings, and observe behaviour.
After critical analysis, they concluded this was indeed a new owl for science, and the first bird species to be discovered in Arabia for 77 years.