This little Black Cap Chickadee, upon seeing its reflection in the window would repeatedly fly up to the glass and retreat just before hitting the window. Sometimes it would brush the glass. This behavior went on constantly for 2 days. Now it's just a couple of halfhearted fly-bys before landing on the feeder. During this frantic window threatening it would occasionally perch on a Rhododendron and glare at me. Normally I don't use image stabilization with shutter speeds faster than 1/100 because of the lag time. But the Sigma 70-300 I used for this shot has a super-fast and accurate stabilization mechanism - love it. It really helped with this little guy because it was never still for more than a fraction of a second... Bob