You step out, cast Invisibility, and step back in. The bird (which seems to be made of glass) ignores you. Without moving any papers around, you can see that the top sheet is a scrawled troop list. It adds up to 400 infantry and 200 cavalry in various places in Arthana; 80 elves; 200 infantry and 7 ships from the Sea Cities; and, in different ink, "Hartwin and 5 golems."
Cast magic missile on the bird. It's made of glass, so it can't be too tough.
Is there a way to let something like a tapestry fall on the cage to cover it?
Make notes of all of the troop numbers and locations and keep searching without disturbing anything.
You put your cleaning supplies in front of her curtain (it's the best you can do), unlock the door with your dagger, and peek inside. It's a messy study. There's a desk strewn with papers, a lamp, and a dusty transparent bird in a gold cage. There are bookcases and two iron-banded chests. The bird turns to you and squawks, "No visitors allowed."
A talking bird? What manner of sorcery is this? Slay the beast and loot the fiend's lair.
Transparent? It must be a guard or ward. Cast invisibility on ourselves and see if the bird ignores us while we search.
Take a brush and start to undust the bird: "No wonder, any visitor would turn around in horror from this mess!"
(can't we close this question?) Right.