Originally posted by Jitatha:

Probably not, they are not everywhere all the time, and are quite uncommon at times. If you kill trolls in caves, those ones do not come back.
Try bigger forest, chop the trees down and mine, and maybe they will hear you.

They will respawn in caves too. It takes some time but they always respawn.
@OP, if you are hunting trolls for troll hide, be sure to mark areas with trolls on the map. If you see a troll, there must be a troll spawner there (it’s not visible but it is somewhere around) and if you kill it, another one will spawn within a couple of ingame days.