Key factors to hummingbird identification include appearance, behavior and territory. Aspects of appearance that bird watchers need to keep an eye out for are throat color and markings, eye markings, bill color and curvature, plumage coloration, tail characteristics, and body shape and size.
The primary factor to identifying a hummingbird is through the physical appearance. The Rufous hummingbird has orange feathers, the Calliope hummingbird has a pink-striped throat, and the Anna's hummingbird has green and gray plumage with bright pink throat feathers.
If physical appearance isn't enough to identify a hummingbird, then looking at behavior is another key factor to consider. For instance, some hummingbirds hover while sucking nectar from flowers while others perch while feeding. The Anna's hummingbird hovers over flowers. Some hummingbirds move their heads and tails when drinking while other hummingbirds make noise during flight. Aggressiveness is another important behavioral characteristic. Some hummingbird species are combative toward other birds such as the Rufous hummingbird.
The third key factor to identification is territory. Knowing which hummingbirds reside in which geographies narrows down the possible identity. The Anna's hummingbird ranges only throughout the West Coast of the United States and into Arizona. The broad-tailed hummingbird inhabits the Rocky Mountains and the Southwestern United States.