(Idea from ShoobaQueen's fanart; check her out on DeviantArt!)
I thought about it, and I think I know where Ghost's fear of birds comes from.
Jimmy is a murderer, so he must run from cops sometimes (at least once or twice, depending if the VenturianTale Gmod world has our sort of laws which I'll go over later).
Officer Maloney is a cop, who can morph into a bird, as he is an alien.
We all know that Jimmy and Johnny are technically the same person, so, technically, Johnny is running from a bird.
This may be why he had a fear is birds. The unanswered question is: why does he say that birds eat you?
A/N - I'm sorry for not uploading on time! So much stuff that my family & friends plan without me knowing! Anyway, I will start uploading more often, whenever I have the time. Thanks for reading, and I'll try to continue, my little adventurers!