If you have been seeing a lot of new twitter birds in profile pictures, those are not actual profile pictures, but the new default profile avatars for users who do not upload their profile pictures.
Many other users with profile pictures too have been sporting those avatars, but that is due to a technical problem on twitter’s end.
The new twitter birds avatar are available in 6 different colors and are randomly chosen for different profiles.
This is definitely a refreshing change from the previous plain old default avatar with o_O. What do you think?