My suggestions, summarised:
* Frequency of large carnivores: reduced significantly. No carnivores at the start of a game in Dwarf Fortress Mode, regardless of area's calmness.
* Frequency of small carnivores: unmodified, but no carnivores generated at the start of a game in Dwarf Fortress Mode.
* Frequency of large herbivores: reduced. Elephants should be rare treats.
* Frequency of small herbivores: increased substantially in Dwarf Fortress Mode, unmodified in Adventure Mode. Dwarves should be hunting rabbits, beavers, pheasants, wild cattle, etc.
* Lethality of small carnivores: reduced. A dwarf should have no major trouble killing a small animal, even if dwarves are shorter than humans; a dwarf should get at worst minor injuries from attacking a small carnivore.
* Appearance of large carnivores: by determination at the start of a new season only.
* Group sizes of all creatures: reduced. Wolves should come in packs no larger than four, for instance. Even one wolf is dangerous.
* In Dwarf Fortress Mode, only large carnivores should be aggressive towards the dwarves. This is not also true in Adventure Mode, which is more hostile because it needs a faster pace to make encounters meaningful. Even elephants would rather run away then risk fighting a dwarf, in the economic version of the game. If a non-aggressive animal gets too close to a dwarf, it merely retreats without initiating combat, so (for instance) a dwarf can walk right through a herd of elephants to collect logs.
In the existing game, starting with a Hunter means the loss of at least one dwarf, guaranteed. The dwarf will attack an animal without getting any equipment and either become grievously wounded or killed. If a hunting dog is assigned, the hunting dog will also be killed. If the dwarf survives, he will become miserable and throw tantrums until he goes berserk. This has the fun side effect of starting the civil war bugs. =)