Here on our farm in Brazil, we are currently having encounters with one. I had been out weeding when I heard the familiar clicking. I looked up and one was sitting on a nest. Although we have seen the nests, after they left, we never encountered one in use.
Two days after we saw the nest we had heavy rain overnight and the next morning the sodden nest was hanging on a half broken twig. Using cable ties we secured it to the branch and hoped that she would return to her two eggs that looked like Tic Tacs.
Shortly after that, the eggs hatched and we two baby hummingbirds. Then our feeder broke and the hummingbirds here are very fickle. I have three feeders that I bought in the States. The hummingbirds here don't use them. They only like the cheap plastic type. I couldn't find a store that sold one in a 20 km radius. My husband then took the plastic flowers off the broken one and stuck them onto my nice one. Finally she started feeding again.
Then, last night, another storm and the branch was damaged and one baby fell out and is gone. Using a strong branch from another tree, we strengthened the the branch where the nest is. The nest was wet and has a hole. The mother didn't return to the nest until late afternoon. I will be glad when this young one has flown the nest, it is so stressful being a surrogate parent.