I was at Lilydale Park in St. Paul, Minnesota the other day when I heard a Cooper's hawk calling. I played a Cooper's hawk call to see what would happen--in my experience it has been soundly rejected by Cooper's hawks. This time, the bird called back, flew closer and called again. I was stunned. The bird came closer, continued to call and then flew right over my head. It was a blue jay doing a spot on Cooper's hawk call. I managed to get a bit of video: [youtube]http://www.youtube.com/watch?v=8Nc1Glrhfrs[/youtube]

Here's a link to a video I took of a Cooper's hawk and you can hear it calling for comparison. Here's a Cooper's hawk call on Xeno-canto.

I was impressed because I have heard blue jays imitate other birds like broad-winged hawks, red-shouldered hawks and even crows, but there's usually something a little off, either they do it too fast or too quiet. But this bird had the sound and the pace down pat. It was interesting to note all the other birds calling in warning in the background. I did notice that the robins gave their warning call, but not the same one that they give for a real Cooper's hawk, the high down-slurred whistle. The robins were wary, but they seemed to sense it wasn't a real Cooper's hawk.