In case it's already been mentioned but I missed it, there is a heatmap function in Fumarporros' TheHunterTools, which can be found here..
http://thehuntertools.huntertalk.de/ Direct link to the specific tool here..
http://thehuntertools.huntertalk.de/thtrack/The only issue with it, for me personally, is that it requires you to manually enter each animal.
(you can mark kill spots, animal tracks, calls and sightings) I used to use it religiously but found it to be
extremely time consuming and so stopped. Also, for what it's worth, the tool became a bit redundant. By noting my kill spots so much, over time it was pretty easy to learn where my reserves' hot spots were/are anyway. The tool itself didn't assist me
directly, since I never once referred back to it for guidance on a single hunt. It aided me indirectly, by simply helping me learn hot spots more as a matter of consequence, rather than the direct data it provides
after the fact. It's a little conundrum or something. If you try it out, maybe your conclusions will vary from mine.
A few other things I learned using it..
You're going to end up only heat-mapping your most commonly used routes and areas. We can't "heatmap" a location that's a kilometer away, only where we go. Makes sense, right?
Everyone's reserves are set up differently and your "mileage may vary" from others', so to speak. Where one player has a hot spot, another player may have a dead spot. Some of the world items that we place in our reserves have a direct impact on the animal behavior/routes we all see in our own reserves, such as feeders, bird decoys, and motion predator decoys. The electronic caller can do the same, but only if/when they're turned on and being used of course. Also, if you ever move these items around, you may effectively be altering your reserves' animal behavior/routes/hot spots.
Heatmapping during MP hunts isn't wise. I personally never used the heatmap tool during MP hunts unless it was with a single friend and we were hunting side by side, because animal behavior/routes could and would be vastly affected by simple multi-player activity alone.
In the end, I think what most "heatmap seekers" really want is a heatmap that's already been filled out. When it comes to putting in actual effort in creating our own personal heatmaps, the result of that effort most likely becomes moot. My advice is; Unless there's ever an automated and persistent heatmapping system created and put into place, don't worry about heatmapping too much. You will learn the hot spots in your reserves as you play and simply enjoy the experience. In this case, I personally think less work is more fun.
Hope my experience in this area helps some, good luck and happy hunting.