The most common hummingbird in the Pacific Northwest (Oregon, Washington
and British Columbia) is the Rufous Hummingbird, but if you live in the Great
Basin or Rocky Mountains, there are other much more common species.  Females
can be particularly problematic.  Rufous, Allen's and Broad-tailed can be nearly
impossible to differentiate without sustained and meticulous observations.

To add to the confusion, Anna's Hummingbirds have expanded their range and
have now even been recorded in Alaska.  Anna's Hummingbirds are year-round
residents west of the Cascades as far north as Victoria, BC.

Please check the following photo pages from hummingbirds.net to make sure you
do, in fact, have a Rufous Hummingbird rather other more regularly occurring
species for your region.

Rufous Hummingbird (Western Oregon, Washington and British Columbia)
Allen's Hummingbird (Coastal California to southern Oregon Coast)
Broad-tailed Hummingbirds (Rocky Mts, particularly Utah, Colorado and Wyoming)
Calliope Hummingbird (east of the Cascades to Rocky Mts)
Anna's Hummingbird (resident along west coast, most common in southern California)