When I saw what this common tern did,
I had to laugh. Terns are interesting birds and I always get very "focused" when they appear on the scene. Things play out before you and if you are not paying attention, you will never see these fascinating details. That was the case with this bird. I have had the wrong idea since youth that birds are limited in what they can do while in flight. For example, thinking that a flying bird cannot turn it's head because it has to watch where it is going. That myth has just kind of hung on in my thinking despite knowing better.
I had been tracking this tern with my lens when it turned and flew directly at me. One of the most difficult shots to take (at least for me) is of a bird flying right over me. I use a tripod which is a little shorter than I would like. Not by much, but I have to stoop over a little even when it is fully extended. To point the lens straight up in the air and continue to look through the viewfinder is a difficult manuever because I have to bend over quite a bit more and try to keep the bird framed. All the time, there are some physics in play regarding the speed of the bird. While it is out in front of me, it appears to be flying at a relatively slow speed, but as it gets closer, the speed increases. It is kind of like a visual equivalent of the doppler effect. By the time the bird is directly over me, it is really moving.
In most cases when this happens, it is all I can do to keep a bird framed and the action of attempting to point the camera through a fast arc causes me to shake the whole set-up enough to end up with blurring in the resulting photos. So, in the split second when this tern went over me, I thought for sure I had missed the picture. I immediately brought it up on the LCD screen and to my great surprise, the image was tack sharp! I couldn't believe it. As a bonus, it was nearly perfectly exposed. The icing on the cake, however, was the fascinating detail that a tern can fly and scratch it's chin at the same time.