Sleepy Bird as her name implies is a sleepy character in the series.
She is rather lazy and rarely does stuff besides sleeping, and usually flies with her eyes closed. She can be active from time to time, but more often is found asleep or snoozing most of the time. She is also the mother of Baby Bird.
Most of the time, she resembles an Angry Bird, likely due to lack of legs and how short-tempered she is.
In Dinosaurs, she uses a giant slingshot to sling herself towards Pocoyo, Pato and Elly.