Conditional sentence

AnonymousCan we use this tense for hypothetical past?

No.

Hypothetical: If the birds had migrated to Oahu, they would have had to fly nonstop.
Non-hypothetical: If the birds migrated to Oahu, they had to fly nonstop.

CJ

CalifJimHypothetical: If the birds had migrated to Oahu, they would have had to fly nonstop.

That looks the same as counterfactual conditional. So the meaning whether hypothetical or not depends on the context, right? I wonder if native speaker would also use "would have" in the if-clause in this case though it seems ungrammatical. Thanks.

Hypothetical: If the birds had migrated to Oahu, they would have had to fly nonstop.

AnonymousThat looks the same as counterfactual conditional.

That's not surprising because "(past) hypothetical" and "counterfactual" are different names for the same thing.

AnonymousI wonder if native speaker would also use "would have" in the if-clause i

I've read from a source that hypothetical means based on guess. It's confusing.

AnonymousI've read from a source that hypothetical means based on guess.

It doesn't.