His secret? Years of experience and a kennel full of superbly trained tracking dogs. His dogs are worked on leash and are capable of following wounded deer for miles. Run out of blood sign, no problem, they will key on body scent. Rain, snow or a day old trail no problem, John and his dogs can generally work it through. Like the Energizer Bunny they just keep going and going until the deer is recovered or John decides the deer was not mortally wounded and reluctantly calls a halt to the search.