Well, I've got some hopeful news:
1) Sunny and Starla (my raven friends) just paid me a visit and I've been seeing a lot of other ravens in the area. Still not seeing/hearing songbirds, but hopefully they're on their way back.
2) I called an avian & exotic animal vet that is thankfully just down the street from my house. The vet said she was surprised they hadn't received more calls/appointments due to the smoke and air advisory. Long story short, she said to monitor the ducks and make sure they have plenty of fresh water and food. If conditions get worse, we start getting ash, and/or any of the ducks show signs of distress, then they should be brought inside or to the vet. Since our ducks are young and healthy, they have a pretty good chance of riding this out until the advisory is over (right now that looks like it'll be Friday afternoon).
In any case, I've set up two pools of fresh water, two water stations, and plan on setting up misters to make the back yard a bit more humid (the vet said humidity is good and even suggested putting them in a shower or steamy bathroom if conditions deteriorate).