Readers offered several suggestions for dealing with our bowling ball problem:

• Some coarse chicken wire covering the bowling ball and your choice of weak or strong current. Might want to get a sparky (Australian: electrician) to suggest a non-fatal voltage... something like an electrice fence amount of unpleasantry : )
• Being in America you've got access to firecrackers right? Could one be rigged to 'go off' when the ball is lifted from the post?
• Goodwill has bowling balls for .75 to $1.25 here so it's cheap enough to replace them. I say, keep replacing them.