It is discouraging to spread precious seed on a field that you have spent a year or more getting ready to reintroduce to native plants only to look over your shoulder and find birds hopping, pecking and consuming the future.
I assume planting in the snow is to get an idea of coverage.
I dilute my seed with kitty litter to get a better spread and also, the litter makes it easy to see where you have or have not spread.
My strategy is to drag my planting with a chain link drag just before and just after planting to loosen a bit of dust and cover the seed slightly. I also wait untill january to plant, there are fewer birds around then. and the seeds are vulnerable for a shorter period of time but they still have time to stratify. If you can time your sowing , do it just before a rain or snow. As a final measure, I get a bunch of store bought bird seed and spread it in another area to bait the birds away from my prairie project.
I have thought about a cat decoy,or a raptor decoy or better yet tie up a cat in that field to scare the birds.

just kidding about the cat...kind of...

I've planted prairie seed on top of snow, too. when I seeded my prairie, I planted half of it on bare soil, and raked it in. The other half I seeded in later, on top of the snow, raked it in, too, and made sure my bird feeders were topped up. I laid out an irresistable spread for them 2 weeks previous to my snow sowing, to get them used to the feeder idea. Suet, cranberries, bread, dried corn, sunflower seeds..the idear was to distract the little jerks.

Dragging the seed in sounds like a good idea, also waiting until this time of year to do it sounds good, too.

Who knows...this will be the second spring, and I'll let you know what gets big enough to the point where I can identify it! I did see some monarda and some dock or compass plant last year, though. Lots of seedlings...I just don't know what kind, yet.

I thought about the cat option, too..but mine are worthless as predators, except on each other. April

Thanks for the good ideas. I feed my birds year-round and the feeding stations are located well away from the plot. I would still like to have input on any experience anyone has had. Winter planting over snow in winter is a technique recommended by several seed supply "authorities."
It just occured to me that the seed might make a welcome target for hungry.