The varied thrush, whose song sounds like a raspy whistle, is a shorter-distance migrant, wintering in Oregon and northern California. They may start leaving Alaska as early as August.
Yellow warblers, small songbirds weighing just 10 grams, spend their winters in Central America or northwestern South America.
As Alaska's brief summer winds down, the daylight hours lessen and the weather is more often blustery and rainy. This change signals the migratory birds who spent the summer in Alaska finding mates, defending territories, building nests, and raising young, to begin their journey south.
Migratory birds face many challenges along their route. They may become disoriented by light pollution and collide with the windows of tall buildings. They have to avoid predators when they stop to refuel and rest. They face adverse weather conditions.
Migratory birds are masters of navigation, using multiple aids to guide them to their wintering destinations. They use the sun, stars, polarized light of sunsets, and the earth's magnetic field for directionality. Experienced adults benefit from their knowledge of the flyways, including landmarks and stopover sites.
Three species of birds who migrate to and from Alaska each year have experienced steep declines over the last few decades: Yellow warbler, varied thrush, and Northern pintail.
Yellow warblers, small songbirds weighing just 10 grams, are named for their bright yellow plumage. They are long-distance migrants who spend their winters in Central America or northwestern South America. Similar to many other songbirds, they primarily migrate at night, but can also fly during the day, and travel in same-species flocks.
The varied thrush, whose song sounds like a raspy whistle, is a short-distance migrant. They may start leaving Alaska as early as August. They migrate in large flocks and spend their winters in the same location. Alaska's varied thrushes migrate further south than those that nest in central and southern parts of the Pacific Northwest. The Alaskan thrushes essentially leap-frog over other varied thrushes to reach their wintering sites in Oregon and California.
The Northern pintail, a dabbling duck, are long-distance migrants. They spend time on molting grounds, typically in the Yukon-Kuskokwim Delta, to grow new feathers in preparation for their flight south. Pintails gather in large staging flocks, gathering more members as they migrate in wavy lines with some ducks flying alongside each other. Pintails fly mostly at night with adult males and unsuccessful females moving south first followed by the young and successful females. Pintails have high fidelity to their wintering locations. Most that nest in Alaska spend their winters in California but some opt to go west and winter in Asia.
The Bird Treatment and Learning Center, based in Anchorage, is permitted by the U.S. Fish and Wildlife Service to rehabilitate any species of bird protected under the Migratory Bird Treaty Act (MBTA) that was signed into law in 1918. The MBTA "provides that it is unlawful to pursue, hunt, take, capture, kill, possess, sell, purchase, barter, import, export, or transport any migratory bird, or any part, nest, or egg of any such bird, unless authorized under a permit issued by the Secretary of the Interior. Some regulatory exceptions apply." The species protected under the act must "occur in the United States or U.S. territories as the result of natural biological or ecological processes." The MBTA is essential to the conservation of wild birds. Bird TLC's rehabilitation program supports conservation efforts by caring for injured, ill or orphaned migratory birds with the goal of returning them to the wild.
Lisa Pajot is an ornithologist and Bird Treatment and Learning Center volunteer.
