Analysis of migrations patterns for Rufous Hummingbird
 
First detection reports collected from throughout the Pacific Northwest from 2000, 2001, and 2002 were sorted into those that follow the coast, those in the western valleys and those east of the Cascade crest.  Figure 1 looks at the relationship between latitude and calendar day.  There is a strong correl- ation between first detection dates and latitude along the coast from the California/Oregon border to Alaska (greater than 99.9%).  A weaker, but still significant correlation is also seen for inland valleys.  There is, however, no correlation by latitude for movement for detections east of the Cascades.

When sorted by longitude, there is an east to west correlation for coastal data, most of this tied to the general westward curve of the coast from British Columbia to Alaska.  Western valleys show a weak eastward trend which may be an artifact of the general trend of interior valleys toward the east as one goes north.

The strong trend (greater than 99.9% confidence) eastward for first detections east of the Cascades which is (based on Figure 1) independent of latitude supports the hypothsis that the majority of Rufous Hummingbirds arriving east of the Cascades come from the west rather than the south

Figure 1: First detection dates sorted by latitude.

Figure 2: First detection dates sorted by longitude.
At the right is a graph of all data from 2000 through 2002 color coded by detection dates and sorted by latitude and longitude.