thx for the feedback everyone :)

Sailing along black forest coast has been the best troll generator for me. (Look for caves).

At night whole forest comes if you make noise, but have not seen any increase in trolls. (could be spawn RNG, those that have them close will get more trolls, those that are looking for them wont get any more from night spawning).

Trolls spawn near troll caves, copper deposits, and Haldor. Once you kill the troll that is there it takes ~3 games day for a new one to spawn in that location.

I found the best way to increase troll spawn is to go mining copper at night

some spawners are generic; eg if you kill the necks you get deer, kill the deer and get boar... etc. Some seem to be more focused, like right outside a troll cave.
try killing everything that moves in your forest patches and it could trigger one, but this is an ongoing counter to the 'just get 50 troll hides instead of metal' threads. About 1/2 the new worlds I have started have not had enough trolls to make a full set of upgraded armor in a reasonable timeframe.

Originally posted by Xea:

I found the best way to increase troll spawn is to go mining copper at night

Seconded. In my current multiplayer game we were wondering where the trolls were... and then we went copper mining at night and sure enough, a 1-star troll showed up.

Start cutting down trees.

they will come

its luck of the draw when it comes to worlds last time i started up a world the entire map contained 3 very very very tiny lil slices of swamp they probably accounted for less then 1% of the total land mass