I owned lurchers that mapped the fields without any sort of device,plus they had an habit of retrieval that few ever witnessed,because they were lurchers.Its all about devices now to assist shit lurchers.Get yourself out on a frosty full moon in the depths of winter,break ice across rough land and let the mutt earn its corn,it will blend into the night,it will hunt and cover the ground,it will chase,lose and use its snout to reconnect and retrieve.Try it.