Would Batscream try to "eye up" a beast former that turns into a typical prey animal, like a sheep or a doe?
Well, yeah. He also eyes up people with altmodes like…frogs, insecticons, bears, other bats, large cats birds, etc etc.
He’s really not picky.
When it comes to actual animals he does have a definite preference for eating deer and rabbits, though, which he’ll hunt or send Waspinator out to fetch for him. There’s not enough energon to sustain everyone on Paradise in most situations, and actually eating food satisfies his techno-organic nature well enough. Though admittedly, at first he’d refuse to eat pretty much any organic food, finding the process disgusting, but quasi-starvation largely solved that problem for him.