I rushed over to her house a block away and brought the bird back to my house to start a feeding regimen until the weather warmed up a bit. As soon as I got home I called Kelly Bryan, possibly the world's foremost hummingbird expert (also not in bed when his phone rang). I welcomed his advice and moral support, but also wanted him to know about the bird in case he wanted to come over and examine it. He said he would if necessary. Fortunately the bird wasn't injured and fed from a hummingbird feeder readily (sometimes they won't). Because of the frigid temperature it had obviously gone into torpor.
Hummingbirds enter a kind of hibernative state on cold nights where their body temperature drops and their metabolism slows to help them conserve energy when food resources are unavailable.
The temperature dropped down to 22° before it started warming up. Meanwhile, I fed the feisty hummer every half hour. In between feedings I kept him in a bag in a dark closet.
After I was able to read the bird's band number, it turns out it was a male Allen's that Kelly had banded here in October of 2011, as a juvenile. (Sorry for the blurry photo but Annie had to use my camera while I held the bird. She didn't know how to focus it.) We were both pretty stressed worrying about the safety of the bird. As you can probably see, he lost a few feathers in my hand. While I've handled hundreds of hummers, Annie had never handled a one, so it's no wonder she was terrified.
When I saw other hummers coming to the feeders outdoors, I released him, even though it was still not above freezing. He flew like a rocket and seemed very healthy, but I haven't seen him back at the feeders here. Another very aggressive hummer keeps fending off the others so fast I can't tell what they are.