The mice darted "into their underground dens" as the owl dived at them? Independent Clause Dependent Clause
These are independent clauses. I say "these" because there are two independent clauses because of the proposition phrases!
The all uses of subordinating conjunctions? I have already taught this lesson, so I have given you the link. I can still explain this here, though.
You may be thrown off by the modifiers, thinking they are subordinating conjunctions, but they are not. If you may have noticed, there are nouns directly after the prepositions so it is a
Be aware of modifiers that look like subordinating conjunctions. Just because a sentence is long doesn't mean it has an independent and a dependent clause.
Think before you do. It's that simple.
Hope this helped you!