Nigel is an character that is part of the Next Generation Angry Birds group.
Out of all of the birds part of this group, Nigel is most definitely the coward. He is often unaware of his surroundings, and most things can startle him. Even a leaf blowing through the air is enough for him to fall on his back.
His relationship with the other birds can very. If it's with someone like Lago, they can get along and hang out. But if it's with someone like Adien and Ethan, they can frighten him and make him think the're going to hit him or something.
When you shoot him into the air, and he falls onto the structure, because he is cowardly, and starts to shake around to keep him from falling, therefore, shaking the structure as well. His power is very similar to Blu's ability from the Angry Birds Rio game.