If you see little brown ants with extra junk in the trunk during these cold months they could be winter ants. (Prenolepis imparis) On tumblr yourselfcola spotted some of these girls enjoying some sugary cereal.
https://www.tumblr.com/plenty-of-spirals/731657554362531840?source=share
These ants are called "false honey pot ants" since deep in their nest they have extra fat ants that store fat for the lean times. They are most active in fall and spring, they like cool weather.
Their nests are very deep.
@futurebird
I don't think I've ever encountered those. Their appearance is distinctive. Usually if I get a call about ants in the winter, it's because they are living under a slab house where the ground is a little warmer. usually Lasius or Tetramorium.
@ambulocetus
Since they don't like heat they don't nest in human homes, although they may search for food there.
So people probably don't have much trouble with them.