Whale Song-Singing Double-Breasted Angle Hooper is a rare species of bird that is capable of singing whale song. It is the natural enemy of the platypus in the wild.
Mothering a Whale song-singing double-breasted angle hooper
At some point, a Whale song-singing double-breasted angle hooper laid its egg in the tree at the Flynn-Fletcher house. When Phineas and Ferb were climbing down from their tree after attempting to make the "sunniest day ever", they knocked the egg out of the tree and caused it to roll into Perry. Believing the egg to be Perry's, and noticing their pet's sudden absence, the boys immediately built the Platy-posterior to keep the egg warm. Fresh from a nature documentary, Candace burst in and took over with her "warm and fuzzy" approach to raising the egg. When the egg hatched at last, it proceeded to attack Candace (who was wearing her platypus "mom suit"), prompting Ferb to inform everyone that the Whale song-singing double-breasted angle hooper is the natural enemy of the platypus in the wild. The bird left after Heinz Doofenshmirtz flew overhead singing whalesong, possibly thinking he was its mother. ("Perry Lays an Egg")