date shot: 10/21/10
location: Fort Harrison State Park, Indianapolis, Indiana
environment: low shrubs and trees at edge of woods
I have seen this bird at the same park during the month of October, and have gone back and forth through the field guides, but I can't seem to settle on an ID. If this bird is migratory, I am curious as to how long it typically stays in an area. We have had a warm autumn, and there still is plenty of seeds and berries. Last night was the first time below freezing, so that might reduce insect availability.
Try option C, none of the above. Looks like you have yourself a Ruby-crowned Kinglet. They are migratory (lots of them nest up here), primarily insectivorous but are remarkably hardy when it comes to cold. They seem to be able to glean enough insects from branches and leaves when it gets cold. The broad eye-ring is a good mark along with the tiny size (and call once you hear it).
Agreed that it's a Ruby-crowned Kinglet. The incomplete eye ring (i.e. broken at the top) is another good mark. One mark that isn't often useful in the field but shows in your photo is that the legs are black and the feet are paler.