Mighty Eagle

The Mighty Eagle is an optional bird that can be unlocked and used in Angry Birds by paying for an in-game app that unlocks the Mighty Eagle for the rest of the game. The Mighty Eagle is the largest, and strongest, of all of the available Birds, and as such, has a limited use. If the Eagle is used on a level that hasn't been completed normally, it can't be used again on another non-completed level until a full hour has passed. If, however, the Eagle is used on a level that the player has already completed, the player won't have to wait before it can be used again. To summon the bird, the player must first purchase him (only once, for $0.99), then, on the top left of the screen during gameplay, an eye button will be placed alongside the "Pause" button. If this button is tapped, all of the standard Birds will instantly disintegrate and a can of sardines will land on the slingshot. Then, the player must simply fire the sardines at the Pig's structure. After a few seconds, the Mighty Eagle will come roaring down from the skies and strike the ground with incredible force, killing all pigs and piercing through any blocks he runs through. Any missed pigs will be instead killed by a massive earthquake the Eagle causes. If the Mighty Eagle is used to pass the level, no stars will be awarded. Instead, the standard scoring system will be replaced by a "Destruction" meter. Depending on how much damage the Eagle causes to the Pig's structure, this meter will fill up to a maximum of 100%. Scoring a perfect percentage ratio will award the "Total Destruction" feather next to the level's icon on the stage select screen. In some scenarios, the default birds will have to be used in conjunction with the Eagle to get 100%. It's species is a Bald Eagle

The Story of the Mighty Eagle
A Red Bird, a Yellow Bird and a Blue Bird happily stare at some newly-laid eggs. Then, a butterfly accidentally knocks over an egg, angering the birds, thus distracting them. The pigs took the opportunity to steal the eggs. Angrily, the birds, next the slingshot, fired themselves at the running away pigs. The pigs' structures couldn't withstand the bird's attacks and ran into their large fortified base.

Upset, the birds were ready to give up. Suddenly, the yellow bird pulled out a can of sardines as an idea to get help from the mighty eagle. Then, the red bird, in fear, went to the cave where the mighty eagle dwells, and asked for assistance while offering the sardines.

A pig came out of the base, scouting later on. He was suddenly knocked on the head by the sardine can. He looked around, and saw the eagle crashing down, and surrendered the eggs, ending the pigs' capture of the eggs.

Trivia

 * The Mighty Eagle isn't yet available in Angry Birds Seasons and Angry Birds Rio.
 * The Mighty Eagle isn't yet available for the PC/Mac version or Android version.
 * The Mighty Eagle isn't yet available in Angry Birds Lite.
 * In the trailer for the Mighty Eagle, the Eagle is shown to live in some sort of cave, and sort of "feared" by the Angry Birds since the Red Bird was very afraid to go ask it for assistance in the trailer.
 * There's a downside to his power, because if you use him to get a Golden Egg, you can't get the Golden Egg.
 * The Mighty Eagle was originally going to be a gray bird with stitches. (http://twitter.com/#!/AngryBirds/status/87870363106676736)
 * The Mighty Eagle will also appear in the 2012 Angry Birds film.