This is a titmouse. A group of these are, yes, titmice. These birds do not migrate from where we live and are here all winter. That pretty much explains the sunflower seed. They eat what winter affords and we add to that with seed. Several varieties of birds who winter here are attracted to the seed, even an occasional Red Bellied woodpecker. The woodpeckers prefer what insects they find on and in tree bark but will take sunflower seed. A companion with titmice is the Carolina Chickadee. These tiny birds hang with titmice and are always together when feeding here. They do not hog the seed but grab one and go immediately to a tree and open and eat the seed there. Just as quickly, they return for another seed.