Ooh it's soo cold here. The temp. was 10 degrees this morning and the high winds, even gusting to 50 mph, made the wind chill minus 18. It is supposed to be even colder tomorrow. This is challenging for the birds. Our White-throated Sparrows are sitting on their feet, as a way of keeping their feet warm.
These are the times when keeping your feeders stocked with high energy food can be life-saving for some species. Birds do not accumulate fat (too bad it's not so for us humans!) very much, only in times just before migration. Many birds can only go a day or two without eating in extreme weather.
We put out hulled black oil sunflower which has a high fat and protein content. We also have 3 suet feeders available. This morning we had a smart Blue Jay eating the suet. We don't see that often. Suet is very high fat, so provides the most calories, ounce for ounce than protein or carbohydrate. The Blue Jay knew what it was doing.