A few years ago I went on a birding walk at UBC Farm with some experienced birders. It was fascinating seeing the forest and the farm through their eyes and ears. I was profoundly struck by how birders use their ears to identify birds and are able to pick them out of a chorus of birdsong. We were sitting on a picnic bench after our walk, and the leader said he heard a Barred Owl. He told us it sounded like this: "Who cooks for you? Who cooks for you all?" I listened closely and sure enough, I could hear it! Since it was daylight, it never would have occurred to me that we'd hear an owl in the late morning. The phrase "Who cooks for you?" is called a mnemonic device. It helps birders recall the library of bird songs they store in their memory. You might think of a different phrase altogether, or use phonetics like this: "hoo hoo hoo HOOO?" I think using "Who cooks for you?" is so much more fun.
I've just taken a book with a CD out of the library called The Art of Pishing: how to attract birds by mimicking their calls by Peter Dunne. Yes, there are lots of silly puns to be made from the subject, which is why some birders call it spishing instead. Pishing is using vocal sounds to manipulate the behavior of birds using their distress calls and the calls of their predators. Pishers make bird sounds like "pish pish pish", to get songbirds to come near to assess the danger. Imitating the sound of the Barred owl then makes them come together and chatter, presumably because their is strength in numbers. The CD teaches you some of the sounds that birders use to help them call out songbirds. There is also an etiquette around pishing: 1) if there are other birders around, ask them if they mind if you pish 2) don't pish in the early morning when birds need to fee the most 3) Don't pish if there are a lot of actual predators around the birds because you'll stress them out and confuse them.
The Starling Cloud Choir (see the post above): For our purposes, using the human voice to imitate birdsong is the way we will create little clouds of birdsong in the garden. So take a listen to this Barred Owl song and get practicing!