Wednesday morning I was shooting the moon when the coyote's started in, I started the video to capture the sound. Hear this all the time and I usually don't pay much attention, but the other day I saw a wolf chasing my dog, so I was hoping to catch it howl. What I got was something different, I edited out 30 seconds of dead time and removed as much hiss as I could. Listen very carefully to the higher notes, and play it a few times if you can. I have the original mov file that came out of the sx40, but it's 244mb. In any case it sounds like a couple of them are whistling a tune. I've never heard anything like before, but then I never really paid attention.