A quarter-inch of ice lay on the surface of the flooded Arkansas rice field in early January. Tank, a 6-year-old German wirehaired pointer, sat quietly in the blind as we waited for the morning’s first ducks. A heavy overcast made it seem colder than it was.

Tank, a solid brown male with a white chest patch and spiky beard, showed his impatience only through the quiver in his knees and an occasional puff of anxious air huffing from his jowls. His pale yellow eyes stayed fixed on the sky.

Four mallards circled in low toward the decoys. Two of us missed; one connected on the trailing bird. From his perch, Tank could see the body-shot drake sail straight away over the field, dropping in the woods almost 300 yards from the blind. With the “Back!” command barely out of his owner’s mouth, Tank hurled himself from the blind, smashed into the ice-coated water and began chunking his way across….