We are working on learning to identify birds solely by their songs. In an effort to do this, we are hanging out in the back yard and watching for birds that we can easily identify by sight, and then listening to their songs so that we will recognize them in the future. The other day we did this with a beautiful red cardinal who was hanging out in a tree just outside the fenced part of the yard.
I happened to have my iPhone with me, so I decided to check out the cardinal call that is on my Peterson's Field Guide application to see how true to life it is. Well, as it turns out, it must be pretty realistic, because the cardinal heard it and started circling just over our heads trying to find the other bird! I felt badly - like I was purposely deceiving him and stressing him out - but it was pretty cool to see him so close up, and to hear him responding to the phone "call"!