It's the Logo of the Zanarkand Abes in FFX which was Tidus' Team. In X-2 Yuna has this on her outfit because of him.
The concept is based on the Gull Wings, the Sphere Hunters of FFX-2, the Token is the Logo of the Zanarkand Abes, the Keychain is Yunas Long Pigtail covered in that Red Cloth. And well there is a Seagull on top.
Well I have Final Mix on PS2 so I know what I am talking about. Those small propeller Heartless in Pridelands still appear on top of the Mountain but they drop small HP Orbs so you can't use the Keyblades Ability - the best and fastest way I know is in the Mysterious Tower because Nobodies don't drop HP Orbs. I choose that place because they are not so powerful if you get in the Danger Area of HP.