From the Super Mario Wiki
Coo Coos are hen-like creatures that only appear in Super Mario Sunshine. They resemble large chickens with two beady eyes, with a star around one. They first make an appearance in Bianco Hills, where they fly around randomly and drop splotches of Graffiti whenever they get near Mario. They later appear in Episode 3 of Pianta Village, where they drop Lava Goop. Coo Coos can be defeated by jumping on them or spraying them to the ground with F.L.U.D.D.. Coos Coos release several Coins with each spray, up to a 1-Up Mushroom.
- Their name is based on the cuckoo, a kind of bird.
- ^ Super Mario Sunshine Prima's Official Strategy Guide, page 18.