I forgot to mention - "schleuss" (in the last line) is not a dialectal form for schliessen. My Langenscheidt's says that a Schleuss is a sluice or lock. As a verb in 1680, it probably meant something like "enclose".

Whoever said that "sie sei nicht here" was spoken by the bird is right. It's the weak subjunctive, and the bird is worried that its mate might not be there.

What about "vor die Tur" in the first line. At present, "vor" is supposed to take the dative.