The Eggs

The eggs are the bird's most desperate items they want in the game. This is why the birds are angry because of the pigs who stole them.

Number of Eggs In Every Game
There are 3 eggs and appears foverer in the original game and Trick or Treat, 1 in Season's Greedings and Go Green, Get Lucky, and 2 in Hogs and Kisses.

More facts

 * They are called "Poached Eggs" in the beginning.
 * The eggs are only shown in Angry Birds Rio when Nigel locks them in a cage. The pigs steal them after they get shipped to Rio.