They were marsh hens, sometimes called rails. Tuck did a great job putting everything together on that video. There were several segments in that video that were shot with an HD Hero mounted to a remote controlled boat. As you can see from the opening shot of the boat, that remote boat can really move and was keeping up with the skiff. The other ones done that way were following the dog on the retrieve, and the shot of me in the bow with the shotgun.