web browser that
supports HTML5 video
Time clauses with “while” and “when” can be reduced by deleting the subject and “be” verb.
If there is no “be” verb, change the verb in the subordinating clause to its -ing form. Sometimes the subordinator (when or while) can be deleted as well.
In the last sentence, the meaning is ambiguous: Are we fishing or are the birds fishing?
Grammar: Participial Phrases