Well...I am sad to announce that she died about half an hour after I posted this message. The other female hummers are usually very aggressive but were coming to the feeder and seemed curious to her that last half hour (none were there earlier). I walked out of the room for a bit and came back to find her not there. I knew she would be under the feeder when I went outside to check.

Aw, how heartbreaking. That's something I hope I never have to witness; I'm sorry you had to :(

Lisa,

I'm so sorry to hear about the hummingbird, but wanted to share some of my experiences working with hummers in an aviary. It's hard for us to know what was wrong with her, so it's entirely possible that there was absolutely nothing you could have done that would have made a difference. It sounds like she may have been pretty sick.

On the other hand, if you ever see such a sight again, I would like to suggest something you might try. Place her in your cupped hands, and blow some warm air onto her. Sometimes, birds can go into a torpor, but may recover if they are given a warm environment and food. When I worked at the aviary, sometimes I would encounter a bird that looked like a total goner. There it would be, lying on the ground, looking dead. On more than one occasion I was able to bring one back simply with the warmth of my hands and breath, and by placing its bill into a sugar water solution. As the bird warmed up, the tongue would flick out, feebly at first, and then more rapidly. The next step was to put it in a warm cage for awhile, with a sugarwater feeder inside, and give it a chance to make a full recovery. Inside of an hour the bird was alive and vigorous again and could be introduced back into the exhibit. With no lingering ill effects, it went on to live a normal lifespan. Amazing. It was so miraculous that I felt like a faith healer!