My character received the spirit of the forest quest a week before mid winter, and performed the ritual 2 weeks later. However, when my character felt the presence of the spirit, it was so dark that the visibility was a single tile, so the spirit wasn't visible (spirits don't wear light vests like humans do). I waited and turned, waited and turned, ... for a fair while, but nothing happened. Then I took a step in a random direction, and was spoken to by a still invisible grey bearded man. I waited a fair while more, but nothing more was said (or seen, of course). I then walked in a rectangle around the ant nest, but nothing was happening or seen, after which I gave up and went to bed. When reporting the quest to the sage that had given it, it hadn't registered, so I guess it will have to sit there for some months to wait for brighter times (there's still two or 3 usages left on the item bought for the quest)...