6th/final time I'm posting this, so just gonna copy/pasta from my alla post
I just picked up a pair of Birdbanes tonight and can say from my personal testing (400-500 hit sample size) that Birdbanes are indeed piercing damage.
Target was lesser colibri, used identical gear in both trials.
Note the average melee low and high, as well as crit average low and high
Destroyers:
http://i36.tinypic.com/wjg9r6.png
Birdbanes: http://i37.tinypic.com/30s7z1l.jpg
if these had about 30 less delay, they would beat destroyers at bird camp, despite the fact that they the extra damage does not apply for ws. However, these are still a great pair of situational h2h (Jailer of temp for one) and great for up and coming mnks/pups for lower level colibri parties.