might not be naivety about new predators but rather, that their passivity is an evolved, adaptive trait in response to living in a restricted environment - basically that the same suite of genetically linked changes that causes tameness and physical size changes in domestic animals is also at work on island animals
That's very cool!

Still thinking I should use those giant owls in a fic even though I haven't written any fic at this point in years. (I managed to get giant penguins into a Stargate: Atlantis fic, which made me very happy.)