Wilson‘s Warbler* | Mick Thompson | Audubon Photography Awards
This past year has given us many headlines about Americans’ pent-up wanderlust—and how and when we might return to our pre-COVID travel habits. It made me think of Zugunruhe, or the “migration restlessness” that has long been observed in caged migratory birds, who “whir” their wings while perched and flutter in the direction of their species’ migratory paths. Some have been observed sleeping less, as though sympathetically flying through night skies with their wild comrades (1).
We humans can curb our wanderlust in the event of a pandemic. Migratory birds, however, have little choice. Crucial for successful breeding, migration is inscribed in a bird’s very DNA: scientists have “read” the journey of a single Wilson’s Warbler, for example, in genetic material from its feathers (4). Migration is a complex event, involving learned behaviors and innate physiological transformations. It culminates in marathon journeys to spring nesting habitat and return flights in autumn to congenial wintering grounds. It’s a marvel what birds put themselves through, without complaint, to survive another year.
Packing for a long journey
Rufous Hummingbird | Tania Simpson | Audubon Photography Awards
It should come as no surprise to hummingbird aficionados that these fierce birds punch above their weight when it comes to migration, with some of the longest journeys in the bird world. Rufous Hummingbirds, for example, fly up to 4,000 miles to nest and hatch their tiny clutches—here in the Pacific Northwest and as far north as Alaska. They can put on a third of their body weight in fat in just one day, quickly bulking up to power their long migrations.
Most Rufous Hummingbirds have left us for the year, having feasted on red-flowering currant and insects (and our feeders). Right now, they’re topping up on late wildflowers in the Rockies, pollinating as they go, on their way south to winter homes in Mexico. Bird lovers in Mexico and Central and South America will celebrate their return on World Migratory Bird Day, observed there on October 9 (and in North America on April 12).
Sadly, these miraculous birds are declining in population. Among other threats, climate change alters flowering seasons, causing confused migrations that are out of sync with food sources. Aside from taking steps to reduce carbon, we can help by increasing connectivity between green spaces. Seattle Audubon’s Capitol Hill Connections Project links patches of habitat in Capitol Hill from Seattle University to Volunteer Park, supporting over 100 bird species in this area. Seattle Audubon also has great tips for growing pollinator-friendly vegetation in urban gardens and rights-of-way. (Just remember if you’re attracting birds, you have a responsibility to provide an opportunity for them to feed in safety, so make sure cats are indoors and your windows are bird-safe—it’s tragic to think these powerful birds come so far only to be brought down by a well-fed pet or pane of glass.)
Capitol Hill Connections habitat corridor
Swainson’s Thrush* | Mick Thompson | Audubon Photography Awards
Transformations and superpowers
The Varied Thrush also migrates, but its journey tends to be shorter. In Western Washington, these orange-streaked birds are altitudinal migrants, leaving their mountain nesting habitat to spend winter in our urbanized lowlands. A shorter journey means less need for physical transformation, but this thrush may adopt a different personality: in the forest, they are reclusive, but here, they may become bolder, showing up at feeders and foraging in the open with American Robins. They can be territorial and argumentative as they compete for food.
The Swainson’s Thrush, on the other hand, shares the Pacific Flyway with the Rufous Hummingbird, returning south this fall after nesting in the Pacific Northwest and Alaska. Their white “spectacles” and shy demeanor might remind us of Clark Kent, but twice a year these small brown birds transform into power flyers, “burning the engine” by consuming their own muscle to stay hydrated.
Like most birds, thrushes migrate at night. Changes in daylight trigger shifts in their melatonin levels, causing the birds to become more nocturnal. During their long dark flight, Swainson’s Thrushes can “nap on the wing,” while parts of their brain remain alert for danger.
“Lights Out” for stellar navigators
Technology has illuminated many mysteries of nighttime migration, and now you can check out migration forecasts using BirdCast for the predicted heaviest migration nights in our area this fall. This information gives us a powerful tool to help birds migrate by reducing light pollution.
Night migrators navigate by the stars. Bright, artificial light in urban areas disorients them, leading them to crash into glass and concrete, causing massive casualties. Overall, window strikes kill as many as one billion birds every year in North America (3). To reduce these collisions, several U.S. cities have worked with local Audubon chapters to implement “Lights Out” programs, darkening urban buildings during migration. Sadly, no city in Washington has done so, but Seattle Audubon has a program in the works, so stay tuned.
Best practices to prevent light pollution
- Turn off your outdoor lights when you’re not using them.
- Ensure outside lights aim down and are well-shielded.
- Install motion sensors on outside lights so they’re only on when needed.
- Choose warm LED bulbs (3,000 Kelvins or under) when converting to LED.
- During migration seasons, draw your blinds or curtains to reduce light spill.
Solutions start at home
Skyscrapers aren’t the only problem. Buildings under four stories—including Seattle’s single-family homes—cause over half of these fatal collisions (2).
You and I can pledge to reduce light pollution by making simple adjustments, including drawing curtains and shades at night, installing outdoor lights with motion sensors, and using “warmer” LED lights (3,000 Kelvins or under). You can also request that Seattle City Light adjust shields on bright streetlights to focus light down into the street.
We can take steps to make glass safer in other ways, too. It’s thought that smaller buildings in greener areas are especially dangerous near dawn, when fatigued thrushes and hummingbirds fly low to find a resting spot for the day. Depending on the light, birds don’t see into your living room—they see inviting trees and foliage reflected in the glass. And birds that seem to “shake off” a collision rarely survive: most die shortly thereafter of intercranial bleeding.
Happily, though, we can help birds see our windows as obstacles, not flight paths or rest areas, by installing window treatments to prevent collisions.
Duck, duck, goose
Snow Geese and Mount Baker (Kulshan) | Yoshiki Nakamura | Seattle Audubon–Seattle Times Photo Contest
While we may not travel to warmer climes this winter, we can thank migration for bringing birds to us. Many ducks winter in the Pacific Northwest, including the domino-colored Buffleheads that dot our lakes. Fairytale flocks of Snow Geese transform Skagit Valley fields. These birds and others will feed and replenish fat stores used on their journey. And we’ll get a great deal of joy watching them. By supporting our parks, farmlands, and natural areas—everything from donating to conservation efforts to keeping our dogs on leashes—we can make sure these hard-working birds get the rest they deserve, until they must do it all over again come spring.
This fall, I’ll look up to the night sky and imagine the living river of determined movement above me, the whisper of thousands of feathered wings. I’ll think about how I might adjust my own behaviors, starting in my own backyard, so that more birds can reach their destinations.
* When information is available, we will link to historical profiles of individuals whose names are currently part of common bird names in English. You can learn more about eponymous bird names in Seattle Audubon’s blog post in support of the “Bird Names for Birds” initiative.
References
1. Berthold, Peter, et al. (2000). Migration restlessness or Zugunruhe in birds—a description based on video recordings under infrared illumination. Journal of Ornithology. 141, 285-299.
2. Hager, Stephen B. et al. (2017). Continent-wide analysis of how urbanization affects bird-window collision mortality in North America. Biological Conservation. 212, 209-215.
3. Loss, Scott R., Tom Will, Sara S. Loss, and Peter P. Marra. (2014). Bird–building collisions in the United States: Estimates of annual mortality and species vulnerability. The Condor. 116, 8-23. 10.1650/CONDOR-13-090.1.
4. Ruegg, K.C., et al. (2014). Mapping migration in a songbird using high-resolution genetic markers. Molecular Ecology. 23, 5726–5739.
About Claire Jackson,
Seattle Audubon Volunteer & Member
I’m a freelance writer and editor based in Seattle. I joined Seattle Audubon in 2015, inspired by Brown Pelicans diving into the Pacific Ocean at sunset. To borrow from Blake, every bird is an “immense world of delight,” offering both refuge and a reminder of a universe beyond my human concerns.
Other articles in this issue of Earthcare Northwest
Science for Conservation: Introducing the Seattle Bird Collision Monitoring Project
Volunteers started patrolling the streets of Seattle this month looking for dead birds. Data generated from their efforts will help Seattle Audubon understand the bird-glass collision issue at a local level, and develop effective conservation solutions.
Migration: Inspiring authors, photographers, and makeup artists alike
Seattle Audubon Board Member, Grace Rajendran, has a passion for books and birds. She interviewed the authors of Pacific Flyway, a book about waterbird migration, and then used her creativity to create makeup looks inspired by migratory birds.