Referred to as the "GaoHeart", the Soul Bird (ソウルバード,Sōru Bādo) is special creature that can increase the power of the Gaorangers' Power Animal combinations, excluding GaoHunter.
Originally, Tetomu performed a ritual to turn the Kage Mushroom into the Gao Egg (ガオの卵,Gao no Tamago) that then hatched into a small blue bird that Kakeru Shishi named Pyochan (ピヨちゃん,Piyochan). During the battle against Highness Duke Org Shuten, Piyochan matured into the Soul Bird to heal the Power Animals and help the Gaorangers defeat Shuten. Since then the Soul Bird has been used as the cockpit in the formations, at the command "Soul Drive, GaoKing!" or "GaoMuscle!". When used with GaoKing, Animal Heart is upgraded to Super Animal Heart, where the blast attack is not only shot from the Power Animal's mouths, but from a cannon inside the Soul Bird as well.
When the Vase Org had transported GaoKing and GaoHunter into another dimension, a feather from Pyo escaped and became Yo, an evil, red-eyed version of Pyo, while in place of the trapped Pyo, a pure good Pi was left. Eventually, Tetomu convinced Yo to help the Gaorangers and become the Soul Bird and GaoMuscle Striker was formed for the first time. After the Vase Org was defeated, the two Soul Birds became one again.