If only 1 save uploaded...
There were 2 Dwarven fortresses in this adventure. I often went to them for different reasons. Mostly to get stuff, which I didn't have in my starting hillock. Animals never accumulated either in hillock or in fortresses. The domesticated animals spawns, just were re-spawning for ever in same places. Dark Tower however had 100.000 troll spawn issue (I was visiting it few times), which entirely exterminated fps there and made the place inaccessible to enter. I just couldn't get rid off animals. No matter how many I hunted down, there were 10x more every time I left that place. I hunted the animals on my road from hillock to both fortresses and time after time there were just more and more of animals on the road. With time there were even animal recruits from those animals, that escaped my ambushes.
Is it even possible in Adventure Mode to exterminate animals? People were writing it is possible, but I lost hope after few months of animal purges. Game got extremely lagy and boring. I think only Fortress Mode offers this rare opportunity to exterminate animal species locally. The worst animals are birds. When birds are tired or hit with bolt, they do not land on ground. They do not fall on ground. Oh no. The birds land and then lie down and rest totally in mid-air, when being totally invulnerable to any shots.
I played this adventure mode for about half year. It was fun. There was lots of stuff still to do and try out. However due extreme lag, caused by endless hordes of animals basically everywhere, it got so lagged... The adventure just died to low fps.