Kanga is the overprotective mother of Roo who is carried with her everywhere she goes. She likes so much being a mother that she's the Forest mother.
Kanga and Roo weren't a part of the group from the beginning, they joined it after an unsuccessful action by Rabbit, Pooh and Piglet. When Kanga and baby Roo came to the Forest Rabbit wasn't very happy so he Pooh and Piglet made a plan. The plan was to capture baby Roo. In the end Piglet was clean and unhappy and Kanga and Roo stayed in the Forest and became a part of the group.