Herons On The Wing

Here are a couple of great blue herons I caught in the act today. They were hanging out together on a small pier off Broadway in The Village on Longboat Key. As I walked along, each one took off, circled around and landed back on the pier behind me. I picked up on this behavior pretty quick, so I kept walking back and forth on the dock until I got some shots I liked. Pretty slick, eh? I think that IS lens is really helping me on shots like these. I'm moving quickly trying to catch the birds in the air, and the stabilization feature makes sure I don't come out with a blurry mess. Anyone else out there use these lenses? Am I supposed to be able to hear the gyros spinning inside? I can hear it on the long lens (55-250mm), but not the short one (18-55mm). I would expect them both too be the same, but they aren't. Maybe I should send an email to Canon...