Ball pythons are well known to eat mainly rodents, a captive bred ball python will be picky about whether its eating a rat or a mouse, or whether its thawed or alive, some even rumor they can be picky about the color but I dont think that one has any real basis. My point is, I dont think it would want to eat a bird.
Get a good locking pvc enclosure for your BP and a lock for the bird cage for peace of mind as Kippykins said and handle one while the other isin its enclosure, but the chances of it happening are already slim.
Sent from my SM-G900P using Tapatalk