I just returned from a successful December bull hunt in 22N where we filled two tags with a 4x5 and a 5x5. We use all the right tools, including Swarovski binoculars, rangefinders, GPS, etc... The problem that sometimes occurs is when an animal is taken on the other side of a canyon, the view of the surrounding terrain always changes after the hour long hike to get to where you "thought" the animal went down. This is especially true in the evening hunt. This results in lost time searching, and the potential of loosing the animal all together.
My question is if there's an instrument on the market that can be used to mark the exact spot of the kill, and would guide you there via GPS? Basically, you shoot, see where the animal dropped, then "mark" the location of the animal in the instrument and allow it to guide you to the downed animal.