Just wondering when a monster (say a wolf) gets a chance for an attack of opportunity they would take their bite but do they also receive a chance to trip their foe or must they choose one or the other. I ask because under combat maneuvers it states ("While many combat maneuvers can be performed as part of an attack action, full-attack action, or attack of opportunity (in place of a melee attack), others require a specific action.") and so no PC would get both attacks during an AoO why would any creature receive the added bonus.
They get a free trip attempt with each bite. How the bite is triggered doesn't matter.
Many creatures have special forms of attacks that automatically happen when they successful use a natural attack.
For example, whenever a wolf successfully bites a creature it automatically gets to make a trip check if it desires.
Another example is an giant squid. If it hit with its tentacle attack it has grab and so it automatically gets a chance to grapple you.
Actually, if a PC gets a combat maneuver "as part of an attack action," then they would also get that maneuver as part of an appropriate attack action made as an AoO.
For example, the Disarming Strike feat explicitly allows you to attempt to disarm whenever you confirm a critical -- whether that critical was the result of an attack of opportunity or not.
One issue here, specifically:
"Trip (Ex) A creature with the trip special attack can attempt to trip its opponent as a free action without provoking an attack of opportunity if it hits with the specified attack. If the attempt fails, the creature is not tripped in return.Format: trip (bite); Location: individual attacks."
You can't normally perform free actions when it's not your turn (speaking is singled out as an exception), suggesting that wolves shouldn't be able to trip from attacks of opportunity.
ETA: Apparently there's a FAQ that specifically overrides this rule for the Trip monster quality, but not in general.
One issue here, specifically:
"Trip (Ex) A creature with the trip special attack can attempt to trip its opponent as a free action without provoking an attack of opportunity if it hits with the specified attack. If the attempt fails, the creature is not tripped in return.Format: trip (bite); Location: individual attacks."
You can't normally perform free actions when it's not your turn (speaking is singled out as an exception), suggesting that wolves shouldn't be able to trip from attacks of opportunity.
ETA: Apparently there's a FAQ that specifically overrides this rule for the Trip monster quality, but not in general.
So yes, animals still get that ability if they have it, on AoO.
One issue here, specifically:
"Trip (Ex) A creature with the trip special attack can attempt to trip its opponent as a free action without provoking an attack of opportunity if it hits with the specified attack. If the attempt fails, the creature is not tripped in return.Format: trip (bite); Location: individual attacks."
You can't normally perform free actions when it's not your turn (speaking is singled out as an exception), suggesting that wolves shouldn't be able to trip from attacks of opportunity.
ETA: Apparently there's a FAQ that specifically overrides this rule for the Trip monster quality, but not in general.
Well, for Grab, Trip, Pull, Push, and Rock Catching, specifically. Not just Trip.
That FAQ allows the creature to do one of five different options (Grab, Trip, Pull, Push, and Rock Catching)it does not state that you can do two separate attacks within an AoO. It states in the AoO description that "An attack of opportunity “interrupts” the normal flow of actions in the round. If an attack of opportunity is provoked, immediately resolve the attack of opportunity, then continue with the next character’s turn (or complete the current turn, if the attack of opportunity was provoked in the midst of a character’s turn)". So basically it is saying that it is an immediate action and so within that immediate action the creature is also allowed a free action (trip) if I am reading it correctly.
It's not an immediate action.
You never get more than one Immediate action and using it consumes your next Swift action. Attacks of Opportunity do do any of this (you can get more than one with a feat, you don't consume your only Immediate action of Swift action when you make an AoO).