The birds stop feeding and disappear about an hour before dusk. They must roost somewhere for the night. That has been my observation. Even if there is birdseed on the ground they disappear till the next day. I notice that in the winter some of them seem to have more feathers, perhaps, for insulation from the cold temperatures. I just love watching birds. And if you can identify a new species, that is even better. Usually, though, I see the same birds. You never know. A bird I saw only a few times was the red breasted grosbeak and last year all a sudden I saw a flock of three outside my window feeding on the ground. In less than two months I will be seeing ruby-throated hummingbirds who have traveled a long distance to come to my nectar I have prepared for them-several thousand miles. I always await their arrival.