To a bird, the scariest thing is a cat with a shotgun. Since people aren't scared of cats, though, the scariest thing to them is just a shotgun. Like this one.
(In-game plural: shotguns)
- The Mines/The Jungle/The Ice Caves
- A Shop (50 Gold)
- The Jungle/The Ancient Burial Ground
- A Tombstone (with a heavy pickaxe equipped)