Noel and Rystral found a nice glade filled to the brim with cabbages! But while sitting down to take a break and munch on delightful treat, their bodies seemed to change. After one cabbage was devoured, another seemed to pop up in its place! Far too late to stop, they failed to realize that this batch of vegetables were enchanted Gysahl Greens! The magic of the food changed their bodies, giving them feather, and making them large and unable to easily move, but why would they want to? Surrounded by an endless supply of food, they wouldn't need to worry about that anymore. They could stuff themselves for as long as they wanted. On that note, I've also heard adventurers seek out these particular chocobos as magical storage devices.