Treebore said:
I like playing Druids, I know how wicked they can be, as a summoner and as a shapeshifter, but as a DM I would say that a spellcasting squirrel/monkey/pick animal is casting a spell it would be detected by a Spot check...
If you're close enough to see the animal doing the casting, then you can do this. Just thinking in terms of the real world, I doubt I'd be able to detect a tiny bird or squirrel doing unusual paw or claw movements from very far away. Of course, this is a game, which doesn't necessarily follow the same reality rules, so in this case I'm looking at the closest ones available.
Even when not trying to hide, I'd say that the size modifier of the creature helps or hinders how easy it is to spot what the creature is doing. It's going to be a lot easier to spot a Hippo trying to cast a spell than it is to spot a squirrel doing it. In the case of a tiny animal, the size modifier is +8 (I think). If it takes a DC10 to spot a human caster at a certain range casting a spell, then by the size rules, I would estimate that it's more like a DC18 to spot a tiny animal doing so at the same distance. I think in actuality the tiny animal would be even harder to detect than that, but this at least attempts to follow existing rules.
Treebore said:
...and then a spellcraft check as per the rules. As someone said earlier, no matter what form my Druid is casting a spell is not "natural behavior", so should stand out and be recognizeable to someone who knows what to look for.
Spellcraft requires training to use, so this method of detection largely limits it to other casters and perhaps a few higher level types that have decided to invest in it. I'm not saying that spellcraft shouldn't factor into the detection, just that it may wind up being overly restrictive. If you are up close to an animal casting a spell, I'd say that even an untrained person might be able to notice something it's doing and figure out that it's casting a spell. So maybe for these purposes, I'd make an exception and allow untrained spellcraft checks (DC15+) to determine if those wierd movements are spellcasting. Still requires the spot check to be made 1st.
In addition, crossing species likely makes detection harder. There are spells that factor in species-crossing (Hideous Laughter) and impose a +4 penalty/bonus on the roll. For crossing creature types w/ spellcraft checks, I'd suggest applying that. That moves the DC to 19+. For an untrained person, it will be pretty difficult, but for someone with enough ranks in spellcraft (which I guess could cover topics like alternate species casting), it's a makeable roll.
What I've discussed above are abviously house-rules, but IMHO they cover the situation pretty well while following existing rules.