I swear that various hummers have their own favorite flowers and colors. Several of mine seem to prefer yellow, yellow anything. I hung a bright yellow thistle feeder from my window one year, and within 10 minutes I had a hummingbird hovering around it checking it out. Once they get used to coming around for their favorites, they'll eventually start feeding from the others too. So I try to keep a good variety of flowers and colors now to attract them. They're worth the hassles, I love seeing them every summer.
