The Owlbear is not a natural creature. It was made by a crazy wizard and is a threat to the actual environment that it exists in, similar to an invasive species.
According to the
Forgotten Realms wiki there’s some in-universe debate about where Owlbears actually came from. Though even if they were created by the gods or came from the Feywild that still that doesn’t negate the fact that they’re extremely destructive so I definitely agree it’s an acceptable druid action to decide culling is the best option.
