Pacific Flyway

The Pacific Flyway spans a vast latitudinal range, from the Arctic breeding grounds in Alaska and Canada to the wintering habitats in Mexico and Central America. Key stopover sites include the Fraser River Delta in British Columbia, the Klamath Basin on the Oregon-California border, the Sacramento-San Joaquin River Delta, and the Salton Sea in Southern California. These wetlands and estuaries are critical for refueling, as many birds travel thousands of miles without feeding. The flyway also includes inland routes through the Great Basin and the Rocky Mountains, connecting to coastal corridors. The Central Valley of California alone hosts over 5 million waterfowl each winter, making it one of the most important wintering areas in North America¹.

The Pacific Flyway supports a remarkable diversity of migratory birds, including waterfowl such as the northern pintail and cinnamon teal, shorebirds like the western sandpiper and long-billed curlew, and passerines including the yellow warbler and Wilson's warbler. Migration timing varies by species: some, like the Arctic tern, travel from the Antarctic to the Arctic, while others, such as the Allen's hummingbird, migrate shorter distances along the coast. The flyway also hosts raptors like the Swainson's hawk, which migrates to Argentina, and the peregrine falcon, which uses coastal cliffs as nesting sites. Many species exhibit leapfrog migration, where northern populations winter farther south than southern populations, a pattern observed in the dunlin².

Conservation of the Pacific Flyway is a collaborative effort involving federal and state agencies, non-profit organizations, and international partners. The Pacific Flyway Council develops management plans for waterfowl and other migratory birds, setting hunting regulations and habitat restoration priorities. The Migratory Bird Treaty Act of 1918 provides legal protection, while the North American Wetlands Conservation Act funds habitat projects. Major initiatives include the Central Valley Joint Venture, which has restored over 200,000 acres of wetlands, and the San Francisco Bay Joint Venture, which protects critical shorebird habitats. Climate change poses a growing threat, altering migration timing and reducing wetland availability due to drought and sea-level rise³.

Beyond the well-known waterfowl, the Pacific Flyway supports several lesser-known migratory phenomena. The bar-tailed godwit makes one of the longest non-stop flights of any bird, traveling over 7,000 miles from Alaska to New Zealand, often using the flyway's coastal winds. The Calliope hummingbird, the smallest bird in North America, migrates up to 2,000 miles from Mexico to the Pacific Northwest, relying on flower-rich mountain meadows. The flyway also includes a significant nocturnal migration of songbirds, which navigate by the stars and geomagnetic fields. Historically, the passenger pigeon used the flyway before its extinction, and the whooping crane once migrated along the coast. The Salton Sea, an accidental lake formed in 1905, has become a critical stopover for shorebirds, despite its high salinity and pollution challenges.

Flyway

A major geographic route used by migratory birds, encompassing breeding, stopover, and wintering habitats.

Stopover site

A location where migrating birds rest and feed to replenish energy reserves.

Leapfrog migration

A pattern where northern populations migrate farther south than southern populations, resulting in a staggered distribution.