Hummingbirds "know" they are among the fastest things in the air. They can be very bold once they get acclimated to the presence of a human, especially one who moves slowly and stays in one spot.
Maybe isn't not you training them but they are training you!
I have a bunch of hummingbird shots that I took way back in the 80's. I should probably dig them out and see if they are worth scanning and posting.
Even though I live in a populated suburban area, right next to an airport, there is still a lot of wildlife around. There are squirrels, raccoons, skunks, opossum and all the usual stuff but there are also deer, turkey and even coyote. You can hear them yapping and howling late at night. A few cats that get left out at night end up disappearing.
Several people I know refused to believe that there are coyote in the area until there was a news story saying that a few had been spotted roaming the streets downtown. Even then, people still denied it. "Yeah, that might be downtown but there aren't any living around here." I always call bull$#it on them. I tell them that I have seen them, I hear them at night and, if they still don't believe me, I show them the picture of the dead coyote I took just a half mile from here:
Dead Link Removed
Anyhow, when you're photographing wildlife, whether it be in urban settings or in the forest, you should do your best to follow the old rule:
"Take only photographs, leave only footprints."