I found this:
Haynar: Bard Song: Agilmente's Aria of Eagles - Will now require wind instrument to play.
http://www.project1999.com/forums/pr...ad.php?t=13535
However, an archived page from a site linking casters realm clearly states that an instrument isn't required:
http://fernworks.net/~dyeomans/DownL....asp%3FId=1012
It may just be working as intended to reduce the number of players trying to kite entire zones somehow.