One of the first lessons that we went over in Texas while working with shorebirds is the plain of focus. Over half of the images you see out there of shorebirds are taken while using a tripod. By using a tripod you are above the bird and thus looking down on the subject. The result is more information in the foreground and background, as demonstrated below.
For the purpose of this lesson try not to focus on the lighting or gesture of the subject. While both of those are important they might make it more confusing to understand this one topic.
If you compare the top image and the bottom imagine, the foreground holds the biggest difference. While both backgrounds blur out a lot the foreground holds more information in focus and thus becomes more of a distraction. If you’re working on a beach that has a lot of traffic and debris you want to manage that as best as possible. A panning plate, in a frisbee, on the ground allows you to slide along and pan with the birds creating better images. The results speak for themselves but it is difficult to get used laying in the sand. Most people are uncomfortable with the big lens that close to sand but by being careful and practicing eventually it becomes muscle memory.
Images Captured with Nikon D5, 600f/4, TC-17EII, on Lexar UDMA Digital Film