If you are serious about your game Angry Birds, you may not like to loose game progress files (game levels) when you switching to a new phone or when reinstalling the game. If it is an Android phone, you can easily backup and transfer Angry Birds game progress files (levels) without even root access.
There are many free apps such as angrybirdsbackup, angrybirdsbackup (seasons) and Rio backup available for download at Android Market, but, since they do not include much instructions, it can be a tedious task, especially for newbie.
Just download and install any of the app mentioned (angrybirdsbackup, angrybirdsbackup (seasons), Rio backup) on both devices.
Install Angry Birds on the new phone and then complete ONE level. Then create a backup using the app.
Install the same app on the old phone and create a backup for the same game.
Use a file explorer (for example Astro) to locate the folder that was created on the new device (it will be named the same as the backup app).
In that folder, you will find two files. Delete them from the new phone and then copy the same two files from the old phone and place them in the same location on the new phone.
Then launch the backup app that you installed and select restore. That’s all.
More detailed information available at XDA Developers