PSA: Aviar attacks with his hero

After I posted my pets guide, I linked it on reddit and got an interesting reply: "Aviar only need to be in proximity of one of your heroes being attacked to activate. Whoever is attacking that hero will be silenced."

I also saw this in another context: while working on my Lava3 article, I asked the guy who posted the strategy I am using why he was using Aviar since (if it only is defensive) it would seem to be very hard to get to have any effect.  He replied, "Aviar, the owl, has been described wrong. It does activate when your hero is in battle. As such it gives us additional silence same as garuda."

Where there's smoke, there's fire.  Or may be.  I decided to test it myself.

After kicking myself for not testing this yesterday (when Guild Wars was on), I finally decided that the best way to test was to try it out in a easy dungeon (basic dungeon 8/14).  So I rigged up my Treantar with lifedrain crests, then I assigned Aviar to a level 20 cupid I have.  I carefully put in the Tre first and let him kill troops.  Then, when a nearby enemy Paladin stepped up to fight, I put in the Cupid.

Sure enough.  Aviar fires green bolts at the Paladin.

Now, this is not sufficient to distinguish the two theories on offer.  But seeing as there are other pets which attack the hero that their owner is attacking, and none which are activated proximately, I am going with theory two.  Aviar procs based on its hero attacking, not being attacked.