This Tiny Bird Crosses the Atlantic Ocean Nonstop — Here's How
This Tiny Bird Crosses the Atlantic Ocean
We analyze the astonishing migratory behavior of the tiny peep, the Blackpoll Warbler.
On an October morning in 2013, a researcher in Bridgeport, Connecticut, examined a mist net. She pulled out a bird so small it hardly fit in her palm. This bird was a Blackpoll Warbler.
Weight: Less than half an ounce (about the same as a sheet of paper)
A tiny geolocator, similar to a sesame seed, was attached to the bird's back before it was released. When the bird was recaptured the following spring, the data from the geolocator amazed everyone in the lab.
The Blackpoll Warbler migrated from New England to South America, nonstop, over the open Atlantic Ocean. This journey took 72 hours and covered about 1700 miles.
Scientists are still trying to understand how the bird's wings, fat reserves, and navigation system work together.
The affirmation of this single data point has changed what ornithologists believe small birds can do. This raises an important question: How can something so small achieve such great feats?
Get Acquainted with the Blackpoll Warbler
The Blackpoll Warbler is not a well-known bird species. It lacks the powerful symbolism of an eagle or the emotional appeal of a robin. Here are some features of the male:
This bird primarily inhabits the boreal forests of Canada and Alaska, making it hard to spot.
Among ornithologists, however, the Blackpoll Warbler is legendary.
Unlike many North American migrants, the Blackpoll Warbler does not head south directly. Instead, it:
Moves eastward toward the Atlantic Coast
Glides smoothly over the open ocean toward South America
This migration path is unusual, risky, and difficult, and it showcases one of the most astonishing feats in animal migrations. The birds that complete it are among the world's greatest long-distance athletes.
A Journey That Should Not Be Possible
To understand the uniqueness of this migration, consult a map. While many birds can stop along the way, the Blackpoll Warbler does not.
In late September and October, these birds gather on the Atlantic Coast—Nova Scotia, Maine, Massachusetts, and Connecticut—waiting for a special weather window. They take off when a high-pressure system creates consistent northwesterly tailwinds.
The Blackpoll Warbler flies for 72-90 hours over thousands of feet of open ocean, with no islands or ships to land on. They fly day and night, making their way across the Sargasso Sea toward the Caribbean and northeastern South America. They only descend at the very end.
The birds that make it across do something comparable to a human completing back-to-back marathons for three days without stopping.
Preparation for Migration
Hyperphagia and Fat Loading
An eleven-gram bird cannot fly for 72 hours on just eleven grams. It must change the math before it leaves.
During the weeks before migration, Blackpoll Warblers experience a strong urge to eat. They consume more food than their digestive systems can handle, allowing them to almost double their body weight.
At departure, they usually weigh eleven grams but may weigh twenty or twenty-one grams.
Most of this extra weight is fat, which serves as fuel for the Atlantic crossing.
The bird must burn through all its stored fat, flapping its wings 20 times every second. Remarkably, Blackpoll Warblers accurately load the right amount of fuel needed for the journey, year after year, with minimal error.
Blackpoll Warblers can fly hundreds of miles over the ocean at night without getting lost. They rely on several navigation systems:
Magnetic Compass: Special proteins in their retinas help them sense the earth's magnetic field.
Stellar Compass: Newer migrants learn the night sky's rotation pattern to find north.
Sun Compass: During the day, they use the sun's position to navigate.
Infrasound Detection: They may detect low-frequency sound waves from ocean waves to understand their position.
These systems work together. If one fails due to clouds or magnetic anomalies, the others help correct the course.
Physiology: Surviving the Journey
Flying across the Atlantic requires remarkable physiological adaptations.
A human flying for 72 hours would suffer severe muscle damage.
Blackpoll Warblers, however, may have elevated antioxidant enzymes that protect their muscles during flight.
While flying, their heart rate can reach up to 900 beats per minute, faster than any mammal, and their respiratory system is highly efficient.
During migration, unneeded organs shrink to save energy. Once they land, these organs quickly rebuild.
The Blackpoll Warbler literally reconfigures its body for the crossing, then reconstructs it afterward.
What Is The Reason Behind This Route?
An outsider might think the Atlantic crossing is a bad idea. Why cross an ocean by air when land is available? The answer is likely time and opposition.
The Challenges of the Land Route
The land route through Central America is longer and slower. Migrants at the same stopover sites compete for limited food resources. These areas often attract hunters, like:
These birds catch tired migrants at bottleneck points.
The Benefits of the Atlantic Crossing
Despite some risks, the Atlantic option avoids these issues. The open ocean has no predators and no food competition. There are no bottlenecks. A bird that fuels up properly and launches in the right wind can enjoy a free ride to South America.
Birds that learned to take this route fared better than those that stuck to land. Over generations, the Atlantic crossing became the dominant strategy for this population.
The Science Behind the Discovery
For most of human history, the Blackpoll Warbler was believed not to cross the Atlantic. It vanished in the fall but returned in spring, leaving people puzzled.
Then came the geolocator revolution of the 2000s and 2010s. These small devices can track birds without changing their behavior. They measure light levels to estimate where the birds go.
Groundbreaking Research Findings
Geolocator studies gave us amazing data on Blackpolls. After tracking the first birds, researchers shared their findings. The birding community was shocked by the straight-line dive southeast over the ocean.
Additional technologies have added more details. Radar can now track migrating birds over dark waters, confirming that Blackpolls migrate in large numbers. Researchers can even determine where birds fed before leaving by analyzing their feathers. Citizen scientists using eBird data contribute valuable insights into bird populations.
The Future of Birds in a Changing Climate
According to a new analysis by UNESCO scientists, the predicted temperature difference in the Arctic by 2100 will be four times that at the equator. This raises important questions about evolution.
Science is currently navigating between confirmed facts and new observations.
Other Birds That Cross The Atlantic: The Blackpoll
The Blackpoll Warbler is the best-known Atlantic crosser, but it’s not alone.
American Golden-Plover: This shorebird also makes a spectacular crossing from the Atlantic Coast to South America. It is larger than the Blackpoll but uses the same strategy of fat loading and choosing the right weather window.
Semipalmated Sandpiper: This small shorebird migrates through the Bay of Fundy, where it builds fat reserves before flying southeast over the Atlantic.
Hudsonian Godwit: A larger shorebird that makes one of the longest nonstop flights of any land bird. It travels up to 7,000 miles from Canada to South America.
Connecticut Warbler: This secretive warbler likely makes a similar ocean crossing like the Blackpoll, though it’s less documented.
Crossing the Atlantic is not unique to one species. Many birds have independently developed this strategy, suggesting that the open-ocean route offers significant advantages.
The Implications for Bird Conservation
Crossing the Atlantic is only possible due to an intact chain of habitat.
Breeding: Birds breed in boreal forests in Canada and Alaska.
Fueling: They load fat in coastal areas like Cape Cod and Nova Scotia.
Wintering: They spend winters in forests in South America.
If any part of this chain is disrupted, the crossing becomes impossible.
Logging and climate change are harming the boreal forests.
Coastal habitat has been greatly reduced.
South American forests are also facing alarming rates of loss.
Since 1970, the Blackpoll Warbler population has dropped by nearly 88%. A bird once common is now scarce in many areas.
Habitat loss at breeding and wintering grounds
Climate change affecting insect emergence
Increased storm frequency over the Atlantic
Despite these challenges, the Blackpoll continues its remarkable journey.
Ways You Can Lend a Hand from Home
There’s a surprising connection between your backyard and Blackpoll Warblers.
In the US, wild and domestic cats kill 1.3 to 4 billion birds each year. Migrants are especially vulnerable after long flights. Keeping your cat indoors during fall migration (September and October) can make a big difference.
Artificial lights can confuse birds during migration. They attract birds to buildings, leading to collisions. Each year, millions of birds die this way. Switch off unnecessary lights during clear nights in September and October.
Cultivating native plants like:
These plants provide energy-rich food for birds. They help migrating warblers fatten up for their journey across the Atlantic.
Support Habitat Conservation
Organizations like the American Bird Conservancy, Boreal Songbird Initiative, and Nature Conservancy work to protect the habitats that Atlantic-crossing migrants need.
By using eBird, you can contribute to valuable data on bird migrations. For example, spotting a Blackpoll Warbler at your feeder in October adds important information to research efforts.
Essential Equipment for Viewing Autumn Migration
The autumn migration along the Atlantic Coast is a key event for birdwatchers. Here are some recommended tools:
Celestron TrailSeeker 8x42 Binoculars
These binoculars are great for watching fall migrants. With a 42mm objective lens, they’re perfect for dawn and dusk. They cost about $120-$150.
Where to buy: Amazon, B&H Photo, REI.
Vortex Optics Diamondback HD 8x42 Binoculars
If you're ready to invest, the Vortex Diamondback HD is a favorite among serious birders. This model offers sharper, color-accurate images. The price is $200–250.
Where to buy: Amazon, Vortex directly, REI, Wild Birds Unlimited.
Sibley Guide to Birds: A Field Guide
The Sibley Guide to Birds by David Sibley remains the go-to reference for identifying North American birds. The fall plumage of the Blackpoll Warbler is especially tricky. Its dull olive-yellow color is quite different from the bright breeding male. Sibley’s illustrations of fall warblers are the clearest you can find in one book.
The eastern edition includes all species found east of the Mississippi River. It is smaller and easier to carry in the field compared to the full North American edition.
You can find this book at:
Approximate Price: $28–35 (January 2023)
The Merlin app helps you identify birds at no cost. It uses sound to detect if a bird is nearby. You can watch your spectrogram light up with warblers while holding your phone during autumn migrations.
Available on App Store and Google Play
If you are serious about observing hawks or shorebirds during coastal migrations, consider a spotting scope. It can help you identify birds at a distance that binoculars cannot reach.
The Ultima 80 with an angled eyepiece offers:
Comfortable viewing for long periods
Estimated Cost: $200–280 Where to Buy: Amazon, B&H Photo, Adorama
Leuchtturm1917 Hardcover Notebook
Many birders wish they had started keeping a migration journal sooner. The Leuchtturm1917 hardcover notebook is popular among birders and naturalists. It features:
An index for easy reference
Cost: $18–24 Where to Buy: Amazon, art supply stores, bookstores
What type of bird crosses the Atlantic Ocean without stopping?
The Blackpoll Warbler is well-known for its non-stop flight from North America to South America, covering about 1,700 miles over open ocean. This journey takes around 72–90 hours.
How far can the Blackpoll Warbler fly continuously?
Tracked individuals can fly nonstop between 1,500 to 1,800 miles. The entire fall migration can be 4,000 to 7,000 miles, with the Atlantic crossing being the only nonstop leg.
What is the duration of an Atlantic crossing?
Data shows that Blackpoll Warblers cross the ocean for 72–90 hours without landing.
How does a small bird survive flying for three days straight?
Dramatically increase body weight
Depart with a favorable tailwind
Undergo physiological changes to prevent muscle damage
Shrink non-essential organs for energy efficiency
What does a Blackpoll Warbler look like?
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Male in breeding plumage: Black cap, white cheeks, black-streaked white underparts, and two white wing bars
Fall migration plumage: Dull olive-yellow above, faint streaking, yellowish below, same white wing bars
Where to see Blackpoll Warblers before crossing the Atlantic?
Look for them along the Atlantic coast from Nova Scotia to the Mid-Atlantic. Some reliable spots include:
Plum Island in Massachusetts
Are Blackpoll Warblers threatened?
While not endangered, their population has declined by 88% since 1970. Major threats include habitat loss and climate change.
Do other small birds undertake similar ocean journeys?
Ruby-Throated Hummingbird
How do scientists track birds flying across oceans?
Motus automated radio receiver networks
Stable isotope analysis of feathers
When should you watch for fall migrants on the Atlantic Coast?
September and October are the best months, especially after cold fronts pass. Early morning, right after sunrise, is the ideal time for spotting.
How can you help migratory birds?
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Keep cats indoors during migration season.
Turn off unnecessary lights at night.
Plant berry-producing shrubs.
Report observations to eBird.
Support conservation organizations.
The Bird That Will Put Everything into Context
When life feels overwhelming, think about the Blackpoll Warbler.
11 Grams: A Paper with Wings
This species can be found in the boreal forests of Alaska or the spruce bogs of northern Canada. In September, it travels east across the continent. Upon reaching the Atlantic Coast, it spends two weeks eating to double its body weight.
When conditions are right, it launches southeast over the ocean. It flies for three days without food or rest, covering over 1,700 miles. It relies on stars, Earth’s magnetic field, and the sun for navigation.
This journey has been happening for longer than humans have existed.
In spring, it reverses the journey and sings from a spruce tree at dawn.
We share this planet with all creatures, and that is worth remembering.
Such tailwinds are essential for the Blackpoll Warbler. They can handle one crossing, but not the other.
