Could Bran warg into a messenger raven, fly to Kings Landing, and poke Joffrey in the eye?

I am watching Game of Thrones on my own time schedule cause I don't have HBO. I just finished Season #3. However, I want to know one spoiler:

Once Bran has mastered warging, could he warg into a messenger raven, fly to Kings Landing, and then try to poke Joffrey in the eye? If he can't, please explain exactly why he cannot?

I get the feeling that warging has ended my love affair with Game of Thrones.