Here are the Animal Track Videos for all 12 Levels. Just click on the desired link and a new window with the video should open.
Following these videos you should unlock the achievement in no time. This is the most time consuming achievement if one already has finished the game... Good luck...
Playing the same level over and over won't unlock the achievement for you. You actually have to collect 90 different animal signs. So in case you finished the game already without getting the achievement, then you will have to replay each level only focusing on the animal signs. The results of hunts and mini games do not matter. Make sure you finish each level so that the collected animal signs get saved... The achievement will pop up as soon as you collected your 90th animal sign.
Also, check your results for each stage and see how many signs you have gathered so far, and see how many additional ones you need. This is the "hardest" achievement in the game because one won't find all the signs unless one follows these videos and in order to get the achievement you need pretty much all the signs for each level. This was the only achievement I had bigger difficulties with when playing the game.
Thanks to Perfekti0nist for this info:
On level 6 is an additional animal sign for the grizzly bear! Right after the footprint in front of the tree, before you enter the bear area, you'll find animal droppings that seem to belong to the bear.
Props to burner6999 for the Videos...