Well, you can always try trapping some zombie slugs and having your gladiators fight them in the arena.
For finding areas rife with conflict, however, I would suggest finding a named mountain for underground goodies, jungles for elephants, gorillas, and mandrills, and serene areas for unicorns. Also, oceans for fish (sometimes landwalking zombie fish) and setting up shop right next to a goblin stronghold.
The thing with any biome, is that it may or may not be full of wildlife, even if it is downright "evil". You can find serene woods with vicious packs of bloodthirsty unicorns, and sinister plains of torment where you may find the occasional mutant butterfly wandering through the sliver barbs.
It's up to luck, really. Both good and bad.
As for biome selection, it indicates what types of biomes might be included in your fort site. The flashing areas indicate the biome in question, and on the side of the screen it will show what kind it is. For instance, you can set up a fortress on a cliffside (no trees, light vegetation, calm surroundings), but there's a forest at the bottom (heavily forested, lots of shrubs, untamed wilds), and a desert at the other end of the map [some trees, no vegetation, calm surroundings, sand).
Be sure to check the stone list underneath each biome to see what you might be getting. You can end up with quite a variety if you place yourself at a sort of "borderland".
s a forest at the o