In all seriousness, you're probably talking about the "tracking" feature that the game has whenever you discover a place where the animal has been.
If you are hunting through the frontier, you'll notice that sometimes you'll come across a white magnifying glass icon over some dirt or shrub or flowers, etc. When you examine this point, it will show a brief cut scene. After that, you will see a notification
saying something like "A rabbit rested here" or "A deer drank water from here" or "A beaver fornicated with a wolf here and left his semen all over the place."
At the same time, the animal you have investigated will show up as a red dot on your map so you can track it. The red dot will not go away until you kill the animal or you leave the area (or start a mission).