It's not so simple as "Too Warm" (Or whatever excuse you wanna pick).
Salt Lake had a ton of water added into it in the last few years. Which pretty much always helps ducks. This is a vast piece of water that supports astounding numbers of ducks. Add in better food, and the birds will find it. They have been stopping there for thousands of years. They will find it.
California got a ton of water the last few years. So much so, that they went from planting 80,000 acres of rice (Pretty much the best crop for ducks calorie wise) to 500,000 acres. Plus a bunch of wetlands that were previously dry (Read "Plants grew there in huge volume" Which is duck food) flooded. The volume of habitat and food available there is hard to comprehend unless you have flown over the region over the last few years.
S OR/NO CAL have lost a ton of important wetland acres. Klamath is well documented over last 30 years. As is Tule. These waters used to support MILLIONS of birds. Which are now going elsewhere. If you take away the places they have gone for a a thousand years, they are gonna bail eventually. We have also lost a ton of water from Summer Lake CA/OR/Nevada border. All of which used to be loaded with birds.
Add in a warm and very importantly dry (If snow buried feed, ducks will hang out for a few days waiting for a melt. But past that, they gotta migrate to food) winter. I have seen several times when E OR/WA/ID got widespread snow, and a few days later, the West side gets a ton of fresh ducks. Never happened this year.
IMO, a lot of the birds stopped their initial migration in Canada. And stayed there, as warm weather didn't force them to move any farther South. Why so many birds short stopped this year is a mystery to me. But I would bet with good confidence we will begin to hear crazy good hunting reports from areas that traditionally peter out in before Xmas. It's well known that ducks love to hang out at the freeze line (So long as food doesn't get buried in snow....which it usually does at some point).
The thing that shocked me most was the lack of wigeon. They predicted a 55% population increase on them. Which makes for a ton of yearling (Easy to fool into decoys) birds. The lower river usually holds a bunch of wigeon. And it did this year.....but it sure as hell didn't see 50% more than were there last year (Or previous seasons). I can only speculate that they stopped short, and never came this far south. Someone had a helluva year on those yearlings. But it wasn't me.
Considering how reliable my usual spots have been for the last 30 years, and how slow they have been all season, all I can say is this year is an anomaly. I fully expect next year, we will go back to seeing our regular amount of traffic in areas we always have. The last 10 years have been great for me. Even though numbers on paper are declining.
If we see a 3 bird limit on pins next year, I would be astonished if my average doesn't go up. I pass on more pins than teal...or spoons....or divers (Save lower river).
Lots to look forward to.