Corpse

In the Angry Birds universe, the term "Corpse" is used to describe the state a Bird goes through after they crash into an object on the board. In this phase, the Bird will appear badly wounded and injured, with dazed/black eyes and crooked beaks. This is also the time when the Bird's strength significantly decreases until it can no longer destroy blocks without the aid of motion. Once a corpse remains still for several seconds, it'll disintegrate into the air.

It should be noted that Black Birds don't have a separate appearance after landing on a structure, as they just flash shades of red before exploding. The Big Brother Bird doesn't have a corpse sprite- it reuses his basic sprite, and the White Bird has two different corpse sprites, depending on if its egg was dropped or not.

Corpses can also prove to be trouble to the player, as if a bird launches into a corpse, it'll have little to no effect on the structure, and if a White Bird fires its egg onto a corpse, it'll bounce off in another direction before it explodes.

These corpse sprites are changed in Angry Birds Rio and Angry Birds (Google Chrome)

The Corpse Glitch
A glitch can be performed when a bird's corpse sprite is replaced by another one when the bird is supposed to be a corpse. To perform it, have a bird fly in the air while using its ability. Fire a second bird at the first bird while the first one is still in the air, using its ability. If done correctly, the first bird's corpse sprite will be replaced by its ability sprite. Rarely, the Boomerang Bird doesn't have crooked beaks if it hits an indestructible structure, but remains opened.