User blog comment:Miskos3/Fairy Tail Episode 231: Gray vs. Doriate, Review/@comment-4933386-20150502105036/@comment-2214433-20150502105215

I'm guessing it's either because Doriate was going to reveal some information to Gray or simply because he was defeated. But given that both him and Minerva were riding the bird before, I guess it's from Succubus.