Bird

Birds are winged, bipedal animals. They can be seen flying above most settlements in the Capital Wasteland, like Megaton, Temple of the Union and Evergreen Mills. They can also be seen in the sky in New Vegas. It is unknown how birds survived the Great War and the nuclear blasts, also they do not appear to have been effect by the radiation unlike most animals that survived.

Fallout 3

 * Birds are not gameworld objects and cannot be interacted with in any way. They exist only as a distant visual effect like far away buildings or terrain.
 * They circle around certain areas that contain some degree of notability (whether friendly or hostile) Megaton, Old Olney and the Alien crash site.
 * Because birds are a visual effect, they can fly through any surface in the Capital Wasteland.
 * Birds also look like flat sheets of black cardboard if you can get close enough.
 * You cannot hit the birds in Fallout 3 but you can in New Vegas.
 * Birds in Fallout 3 stay in the sky and do not land like in New Vegas.

Fallout: New Vegas

 * Birds also appear in Fallout: New Vegas; see raven.
 * They cannot be targeted via V.A.T.S. but can be shot and killed free hand for a small gain of 1 XP.
 * They spawn on the ground and fly away if approached.
 * Birds are marked as "Friendly" on your compass.
 * Birds are not attacked by enemies, so when a friendly mark on the compass appears amongst a group of enemies, the player may believe that a friendly character may be under attack. When the player approaches to save the character, the bird will fly off, leaving the player to fight the enemies.