I have found www.eqdruids.com to be an invaluable resource.

Here is what they say in the Battle Tactics section; it pretty much agrees
with what Su said, but gives a slightly different perspective. This is a
direct cut and paste from the web page, so please don't flame me for the
slightly offensive language contained herein.

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I have been sent many emails on both sides of the coins on animal slaughter
for druids...here are the FACTS...role play to what you want.

The only animals you SHOULD NOT kill due to faction hits are the bears
inside the city of Sure Fall Glades.

If you kill animals near certain NPCs (Holly...bitch) and other rangers and
druid NPCs throughout various zones, they will assist the animal and kick
your butt. You do not suffer a faction hit for this combat, just a corpse
retrieval.

On the flip side, animals are the only way to obtain pelts and skins. In
addition at some levels they are the only obvious choice in killing for
experience. In addition we have four lines of spells devoted to jacking
with animals. To me it is clear that game intends for druids to whack on
animals with no remorse. Many people feel this is against their own sense
of role-playing a druid. It is important to note that many monsters who we
would consider an 'animal' are not (i.e. spider variants). The best way to
tell is to try to cast a charm animal variant spell on them and see if you
get a message about only being able to cast on animals.

As a player, I prefer to kill MOBs that have loot that is worth messing
with. With the exception of ruined pelts at low levels, I have found
animals to be not worth the monetary effort (well mammoth tusks and grif
feathers are nice).

Do as you will, but I think that you will get very little reward for NOT
killing animals and your experience on Norrath will be more difficult as
many of your spells will go unused.

However in the sense of a druid is a protector of nature, make sure players
(and yourself) clean up all corpses so they don't lay around to decay, also
use anything you pick up of a corpse, don't just dump it on the ground. In
my sense of role-playing, Norrath will ALWAYS spawn more monsters than
players can wipe out, so my job is to help maintain an effective balance...

******

Hope this helps

Froondor
lvl 36 Wood Elf Druid
Tarew Marr