Rio Characters are characters that only appear in Angry Birds Rio. Here is a little info about them.
Blu- Blu has the ability to push rocks. He is only seen in Angry Birds Rio. He is first seen in Theme 7-1.
Jewel- Jewel is a Rio character in Angry Birds Rio. She has the power to fly straight. Blu is sometimes holding on to her.
Nigel- Nigel is a bird that is not on the birds' side. He is not an obstacle or anything. Sometimes you will see him if you fail a level. He is only seen in Angry Birds Rio. He is the only enemy bird.
Luiz- Luiz is a dog. He is an enemy but he sometimes helps you. If a ball lands on ground, he will chase it. He is playable and he is only seen in Angry Birds Rio.
Caged Birds- None