What do birds eat when it snow?

Herbivorous, carnivorous, or omnivorous birds exist. While most birds eat seeds, worms, plants, sap, berries, nuts, tallow, or meat, some are picky and won't eat anything. Many birds could have been pecking at the seeds. Their cone-shaped spout, on the other hand, makes it easier to consume these difficult foods.

This is not factaully proven but from what I have see they eat things such as deez nuts  

They dig into snow a little with their beaks, they find other little critters crawling around on a tree. Sometimes it is even easier for them to spot insects when the background is all white. However, your point is legitimate, there is a severe shortage of seeds in the winter. Some people have bird feeders in their yards and the crowd of birds increases 20 fold in the winter, little birdies looking for a hand out. If you do that, just remember, they will come back every winter, including the next generation. 

That's why they eat very heavily before it does.

You can always put some seed or crumbled bread out for them, if it worries you.

(:

ice worms?

They fly south. I knew that when I was 2.