The point at the bottom of each dive is more or less fixed. By the time a Rufous Hummingbird has completed his display, he has staked out a cylinder of air space about 30m high and 20m across. Calliope Hummingbird is a species most regularly found in open, high mountain areas. It has a display which is similar to the front end of the Allen's display. Generally, pendulum arcs are broader and there is no final dive.
Calliopes are also, usually silent.
Anna's Hummingbird is a recent addition to the avifauna of the Pacific Northwest first recorded in the late 1940's in Oregon. Nests with eggs have been found in Oregon as early as February. The Anna's display is also typically more 2 dimensional than the Rufous. Plumage Characters One cannot assume that green-backed male Selasphorus hummingbirds are Allen's Hummingbirds. Most Rufous Hummingbirds have some bits of green and a few have remarkable amounts of green.