It's currently unknown, I think, whether "forest cover" is to be taken literally or not. I've definitely seen the tracks go out into open terrain, but I can't remember if any of the "last" tracks have been in open terrain. In my last case new tracks appeared after a day of fruitless burning on "last" tracks, and I eventually found the missing creature.
Thus, you probably have to search each and every tile within the circle (probably excluding the village). Also note that it's easy to miss the tracks in spruce forest because of the limited visibility. In pine forest you can get away with moving on the overland map and zoom into each tile, look around, and then zoom out again, while you have to be lucky for that to work out in spruce infested terrain. I walk back and forth mostly zoomed in for one row/column of tiles at a time, which is extremely tedious.
Also, you're unlucky to get a boar, as, unless the track changes have modified it, you can't see the difference between the tracks of a tame boar and those of a wild one.
It is the most tedious quest in the game, and one I'm prepared to skip or fail because of the extreme tedium involved.
Topic: Spoiler alert: don't understand quest about missing animal (Read 3939 times)