Paths are fences? Anyway, I can't use them as path or as fences.
It's difficult to imagine what they are thinking. I imagine something like "The Settlers / Serf City", but 100% automatic. In that game, one of the guys can go from the home to a lake, fish for a while and return to the home. So it's clear what the guy is doing. I don't expect you to create a very complicated economy like in that game.
My suggestion is to add a few visible task. Some ideas:
Perhaps trees can drop fruits from time to time, and when a Lemming collects one of them it grows or just stop starving.
From time to time there appear little crowns, when they pick one they get a permante crown graphic, and that increase their matting chance and after matting the crown disappears.
More colors, perhaps split them in a top and down color so I can identify them.
Add some random weight to their movement selection so they have "personalities". One of them likes to walk straight, another likes to move in circles, ones want to climb, another wants to go to the beach, ...