The route is elliptical rather than a straight there-and-back. Northbound birds move early along the lowland Pacific coast, arriving with the first coastal blooms. Southbound birds instead take the Rocky Mountains and Sierra Nevada, where subalpine meadows peak in late summer, so the loop keeps the birds in step with flowering rather than with geography.
Relative to body size the journey is among the longest of any bird. A rufous weighs roughly three to four grams, so the migration is on the order of a million body lengths, a comparison frequently cited with varying arithmetic.
The species breeds farther north than any other hummingbird, reaching southeastern Alaska, and is notably aggressive at flowers and feeders, driving off larger hummingbirds. North American survey data show a sustained decline, and the species is assessed as Near Threatened. Which part of the annual cycle is driving that decline, breeding habitat, migratory stopovers or wintering grounds, has not been isolated.