I claim the ornamental design for a mud mat for waterfowl hunting, as shown and described.
FIG. 1 of the drawings is a perspective view showing the top, left side, and front of a mud mat for waterfowl hunting embodying the design of my invention;
FIG. 2 is a top view of the mud mat for waterfowl hunting;
FIG. 3 is a perspective view showing the bottom, right side, and back of the mud mat for waterfowl hunting; and,