(click on image for larger version)
In Wisconsin the single hummingbird species we expect to see is the Ruby-throated Hummingbird, but there are nearly annual sightings of Rufous/Allen's and a few Green Violet-ear records, but generally up north. I recently put out a nectar feeder to attract hummingbirds and now there are 3 or 4 regular visitors.
Apparently, hummingbirds aren't interested in the concept of sharing and will often chase each other away from the feeder. They seem to lead of life of constant intensity and when not in hot pursuit of each other, they'll even chase other bird species around. A few weeks ago at Horicon Marsh I observed a hummingbird harassing a Red-tailed Hawk. It makes you wonder just how big these tiniest of birds think they are!
An excellent on-line resource for learning all about hummingbirds and attracting them is Hummingbirds.net. There you will find information on nectar mixes, feeders, migration, what to do with sick or injured birds, conservation efforts, maps, photos and a whole lot more.
Link: Hummingbirds.Net
Link: All about the Ruby-throated Hummingbird from Cornell Labs
Ruby-throated Hummingbird image © 2005 Michael Allen McDowell