Angry Birds 2/Extra Birds

What are the Extra Birds?
“Have you noticed the question mark next to Terence? Tap it and you will see we have made space to expand your flock!”

To unlock the extra birds, you need to collect special keys available on the map. Remember that whichever bird you choose can only be unlocked once.

The extra birds behave a bit different from the usual flock:


 * They get unlocked by special keys. Just like the rest of the flock, you can find the keys in the level map and choose which bird to unlock.
 * They don’t have hats. Because of this, their card power is determined by the bird's level as well as the hatchling and slingshot level.

In older versions of the game, the extra birds will join your flock in 4 hours and then go to sleep in 9 hours. To pick an extra bird, the player must select the bird’s expired sleeping time and then press Pick! and then the playtime will start to run. If one of the four birds are sleeping, the player has a choice of waiting and choosing another bird to join or to pay gems to skip through the wait time. Remember that the birds are only playable when the playtime is available and will expire when the playtime ends, simultaneously starting the sleeping time.

In the newer version of Angry Birds 2, the extra birds work differently. One of the four birds will be still playable without sleeping.