"Dug in," is a phrase used to describe someone who is firmly settled or stubbornly holding their position. In the context of the book "Flush" by Carl Hiaasen, it may refer to a character's attitude or approach towards a situation, indicating determination or resistance to change.
The phrase suggests a sense of persistence or defiance, which can be a theme in the story as characters face environmental or legal battles. In "Flush," such expressions highlight the characters' struggle to protect their surroundings or stand firm against opposition.