Under a cloudy sky, the lighting was right at any subject angle and throughout much of this day at Blind Pass in Captiva, Florida. This giant softbox-like lighting permitted me to maneuver to the ideal angle for this subject (from the side) and the NatureScapes Skimmer Ground Pod II allowed me to comfortably work from right on the sand.
This low perspective caused the background content to be farther away. That distance, combined with a long focal length and close primary subject, meant that the background became significantly blurred. When it becomes a blur, the background's color and shapes become the primary concern.
In this case, the ocean was my background. The wave patterns, including breaking waves, supply the gently-changing color and shapes.
When the ocean is in your frame, shutter release timing often matters as the ocean is constantly changing. A wide variety of waves shapes worked well for this situation, but my final selection included not only the willet with ideal head and body angle, but also with most breaking waves (white color and shape) avoiding the bird's outline.
As I've said before, the Canon EOS 7D Mark II and EF 100-400mm f/4.5-5.6L IS II Lens make a great birding combo.