First, allow me to set the scene. It is late evening. The sun is a couple degrees above the horizon and dropping fast. I am shooting Snowy Plover in the sandy foredune. So, we have light that is nice and warm, directional but dropping rapidly and birds that are small, well camoflaged, skitish and fast. So what is one to do?
Birds exhibit three different rates of movement which works well for the photographer. Their head and body tend to move at a relative slow pace. The feet move at a relative moderate pace and their wing tips move at a relatively fast pace. That is why we are able to capture stunning images of a huming bird with the head and eye tack sharp while the wings are a blur. The key term in this piece of the concept is relative as some birds even the body is moving quite rapidly just not in relation to the wings.
So, given all this, what one does (or, rather, what I do) is not worry about the fast moving parts and focus on getting a crisp clean head and eye and, if possible, body. The blur of the wings and feet only add to the image by imparting that sense of speed and action that makes it dynamic. Panning moves the camera in the same direction and plane as the body and ignores the up down pumping of wings and feet. Shutter speeds are set as high as I can by selecting a wide open aperature. And, I shoot.
Still, sometimes it just doesn’t work out.
And, Sometimes it does.