On 13 October 2022 a five-month-old bar-tailed godwit lifted off from southwest Alaska and did not land again for eleven days and one hour. No food. No water. No rest. It came down in Tasmania — the longest non-stop journey ever recorded for any animal. Every autumn billions of birds attempt smaller versions of the same impossible thing, and every year there are fewer of them.
Godwit “B6”, a juvenile carrying a 5-gram solar satellite tag, Alaska → Ansons Bay, Tasmania. Track models place the distance between 13,391 and 13,560 km; Guinness certified the upper figure.
The Pacific offers a godwit nothing: no shoreline, no mudflat, no insect. That is precisely why the route works — a bird that cannot stop is also a bird that cannot be eaten, infected, or blown off a coastline. B6 flew the empty middle.
SOURCE: USGS ALASKA SCIENCE CENTER (2022); GUINNESS WORLD RECORDS (2023). MAP IS A HAND-SIMPLIFIED SCHEMATIC; THE ARC SHOWS ROUTE SHAPE, NOT AN EXACT GEODESIC. THE SIX MARKERS DIVIDE THE TRACK INTO EQUAL PARTS — ROUGHLY ONE PER 1.6 DAYS ALOFT — AND ARE ILLUSTRATIVE, NOT LOGGED FIXES.
Every migrant is solving the same equation — fuel carried against distance to the next safe ground. The answers span two orders of magnitude.
SOURCES: HUMMINGBIRD ≈500 MI / 800 KM GULF CROSSING IN 18–22 H (USDA FOREST SERVICE; CORNELL LAB) — MANY INDIVIDUALS INSTEAD TAKE THE OVERLAND ROUTE. BLACKPOLL WARBLER ≈2,500 KM OVER THE ATLANTIC IN ~3 DAYS (DELUCA ET AL., BIOLOGY LETTERS, 2015). E7: 11,680 KM IN 8.1 DAYS (GILL ET AL., PROC. R. SOC. B, 2009). B6: USGS / GUINNESS, 2022–23. TERN: 70,900 KM MEAN, RANGE 59,500–81,600 (EGEVANG ET AL., PNAS, 2010). SWIFT: HEDENSTRÖM ET AL., CURRENT BIOLOGY, 2016.
A godwit preparing to leave Alaska is not the same animal that arrives in Tasmania. In the weeks before departure it rebuilds itself into an airframe: flight muscle up, fuel up, everything else deleted.
SOURCE: PIERSMA & GILL, “GUTS DON'T FLY: SMALL DIGESTIVE ORGANS IN OBESE BAR-TAILED GODWITS,” THE AUK, 1998; PIERSMA ET AL., FUNCTIONAL ECOLOGY, 2003.
Fat carries roughly eight times the usable energy per gram of the same mass in protein or carbohydrate stored wet. For a bird, fuel is the only cargo worth taking — and a stopover on a crowded Asian mudflat costs days of feeding, exposure to predators, and habitat that is disappearing fast.
So the godwit trades safety for arithmetic: leave heavy, fly the empty ocean, arrive at roughly half the departure weight, and start eating.
Also true of the tag
B6's transmitter weighed 5 grams — about the mass of a single sheet of A4 paper — and was solar-powered so it could outlast the flight.
Most migration happens at night, invisibly, high overhead. The same NEXRAD radars that watch for thunderstorms also see the birds — and the seasonal totals do not balance.
SOURCE: DOKTER ET AL., “SEASONAL ABUNDANCE AND SURVIVAL OF NORTH AMERICA'S MIGRATORY AVIFAUNA DETERMINED BY WEATHER RADAR,” NATURE ECOLOGY & EVOLUTION, 2018 — 143 RADAR STATIONS. THE SPRING RETURN IS ROUGHLY A QUARTER SMALLER THAN THE AUTUMN DEPARTURE: THAT GAP IS WINTER MORTALITY.
Nobody noticed a single extinction. What happened instead is that ordinary, abundant birds — sparrows, warblers, finches, swallows — got less abundant, everywhere, for fifty years.
SOURCES: ROSENBERG ET AL., “DECLINE OF THE NORTH AMERICAN AVIFAUNA,” SCIENCE, 2019 (529 SPECIES, 1970–2017). RIGAL ET AL., “FARMLAND PRACTICES ARE DRIVING BIRD POPULATION DECLINE ACROSS EUROPE,” PNAS, 2023 (170 SPECIES, 20,000+ SITES, 28 COUNTRIES, 1980–2016).
SOURCES: RIGAL ET AL., PNAS 2023 (FARMLAND SPECIALISTS, 1980–2016); ROSENBERG ET AL., SCIENCE 2019 AND 3BILLIONBIRDS.ORG (GRASSLAND −53% ≈ 720 MILLION BIRDS; SHOREBIRDS >⅓; WATERFOWL +56%; RADAR-MEASURED SPRING PASSAGE −14% OVER THE PRECEDING DECADE). WATERFOWL RECOVERED BECAUSE WETLANDS WERE BOUGHT, PROTECTED AND FUNDED — THE ONE GROUP THAT GOT A POLICY.
Birds that navigate by stars and magnetic field lines meet cities that were not there for most of evolutionary history. The largest single fix is a light switch.
Median estimate of annual bird–building collision deaths in the United States; range 365–988 million. Roughly 56% at low-rises and 44% at residences — under 1% at skyscrapers.
Halving the lit window area at Chicago's McCormick Place cut spring collisions elevenfold (sixfold in autumn). Two decades of nightly carcass surveys underpin the estimate.
Median U.S. estimate, range 1.3–4.0 billion; about 69% attributed to un-owned cats. The single largest direct human-linked source of bird mortality measured so far.
SOURCES: LOSS, LOSS, MARRA & WILL, THE CONDOR, 2014 (BUILDINGS); VAN DOREN ET AL., PNAS, 2021 (MCCORMICK PLACE); LOSS, WILL & MARRA, NATURE COMMUNICATIONS, 2013 (CATS).
B6's flight is a piece of engineering that took millions of years to tune, and it terminates on a specific mudflat on a specific coast. The flight is not the fragile part — the two ends are. Almost everything on this page that got better, got better because people did something deliberate.
Curtains drawn, upper floors dark, exterior floods off between about 11pm and dawn during spring and autumn passage. Cornell's BirdCast publishes live migration forecasts three days out — dark on the ten biggest nights buys most of the benefit.
Collisions are dominated by low-rises and homes, not towers. External screens, cords, or dot patterns spaced ~5 cm on the outside of the pane are what actually work; decals on the inside largely don't.
An indoor or catio cat removes a bird-mortality source larger than every wind farm and every skyscraper combined, and the cat lives years longer.
Native plants carry the caterpillars migrants actually refuel on. And the waterfowl curve shows the bigger lever: protected, funded wetland and mudflat habitat is the one intervention with a proven +56%.
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