the other bird reference occurs in season seven, and i was hoping someone could explain it to me. :) i guess i'm not a "clever girl."
the other reference to "throwing off sparks" occurs in the same other steven bochco episode. i just thought it was interesting that those phrases, "throwing off sparks" and "corpus delicti" both showed up in both episodes...definitely evidence of his particular writing style, i think.
The reference is the nightingale in "Try and Catch Me."
I think Abigail was just testing to see if Veronica could hear the tape recorder through the safe, to make sure that nobody would be able to hear Edmund's screams.