The birds have no such heat source. They must keep moving, keep eating, or perish. So I watch cardinals and jays and sparrows and grackles flit out and back, up and down. They cluster around the feeder, drain it in hours. In between, they fluff their feathers and bury themselves deep in the azalea bush.
Downy woodpeckers nibble at the suet block. Sometimes a pileated woodpecker joins them. The squirrels want in on the action, too. Why they don't partake of the large pile of seed on the ground below the feeder I'll never know. I think they just like to mess with us.