The Longest Animal Migrations: Records, Routes, and Navigation

An Arctic tern weighs less than 125 grams (about 4.4 ounces), yet tracking of 11 individuals showed some of them flying more than 80,000 kilometers (50,000 miles) in a single year, from the Arctic to the Southern Ocean and back. Over a life of roughly 30 years, that adds up to more than 2.4 million kilometers, about three round trips to the Moon. This article ranks the longest animal migrations that scientists have actually tracked, explains what each record measures, and shows how animals find their way over distances no map-reading human could manage without a satellite.

The short list: who travels farthest, and how it was measured

Migration records are slippery because "longest" can mean four different things. It can mean the longest annual round trip of a species, the longest journey of a single tracked animal, the longest nonstop flight, or the longest one-way displacement between two sightings. Mixing those up is how headlines end up claiming that a whale "beat" a bird.

The table below keeps the categories separate. Every row names the measurement and the source, so you can see why the numbers are not directly comparable.

Animal	Distance	What the number measures	Source
Arctic tern (Sterna paradisaea)	About 70,000 km typical, some above 80,000 km	Annual round trip, 11 tracked birds from Greenland and Iceland	Egevang et al., PNAS, 2010
Sooty shearwater (Ardenna grisea)	About 64,000 km	Annual loop from New Zealand across the Pacific, about 19 birds	Shaffer et al., PNAS, 2006
Western gray whale "Varvara"	22,511 km	One whale's round trip, 172 days	Mate et al., Biology Letters, 2015
Leatherback turtle (Dermochelys coriacea)	At least 20,558 km	One female tracked 647 days; signal lost	Dutton, Benson, and Hitipeuw, SWOT Report, 2008
Bar-tailed godwit (Limosa lapponica baueri)	More than 13,500 km	Nonstop flight of one juvenile, 11 days, 2022	BirdLife International
Humpback whale (Megaptera novaeangliae)	At least 13,046 km	Great-circle distance between sightings in 2013/2017 and 2022	Kalashnikova et al., Royal Society Open Science, 2024
Monarch butterfly (Danaus plexippus)	Up to about 4,800 km (3,000 miles)	One-way flight, eastern population	U.S. Fish and Wildlife Service
Caribou (Rangifer tarandus)	More than 1,200 km	Straight-line round trip between migration end points	Joly et al., Scientific Reports, 2019

Two lessons fall out of the table before we look at any animal in detail. First, the record holders are not the biggest animals. Birds dominate because flying through moving air is cheaper per kilometer than swimming or walking. Second, almost every figure is a minimum, because tags fail, batteries die, and straight lines understate real paths.

The Arctic tern's pole-to-pole commute

Arctic terns breed in the high Arctic and sub-Arctic during the northern summer, then fly to the Southern Ocean for the southern summer. Because they spend the northern summer under the midnight sun and the southern summer under Antarctic daylight, they live through two summers a year. For decades, textbooks put the round trip near 40,000 kilometers.

That estimate collapsed in 2010. A team led by the Danish ornithologist Carsten Egevang fitted terns breeding in Greenland and Iceland with miniature geolocators (1.4 grams each), recaptured 11 of the birds a year later, and read the logs. The paper, published in the Proceedings of the National Academy of Sciences, reported that some individuals flew more than 80,000 kilometers in a year, about double the textbook number. National Geographic's summary of the work puts the typical round trip at about 70,000 kilometers (National Geographic).

The terns did not fly south in a line. They took an S-shaped route through the Atlantic, with a previously unknown stopover in the mid-North Atlantic where birds from both Greenland and Iceland fed for roughly three to four weeks, mostly in August and September (Egevang et al., 2010).

Why the detour makes sense

Birds from the same colony took one of two southbound routes, one hugging the African coast and one crossing toward South America, but all returned along a similar S-shaped path that crossed the Atlantic near the equatorial doldrums. The authors concluded that the terns favor productive stretches of ocean and use the prevailing global wind systems to cut the cost of flying (NERC Open Research Archive abstract).

A sailboat makes the logic easier to see. A skipper heading upwind does not point at the destination; she tacks, adding miles on the chart but keeping the sails full. A tern that detours through steady trade winds and a food-rich stopover is doing the same arithmetic, trading extra distance for cheaper distance.

Timing differed by direction. According to National Geographic's account of the study, southbound journeys averaged about 93 days, with the fastest birds taking 69, while the northbound return averaged about 40 days at roughly 500 kilometers per day. The slow outbound leg includes the stopover, so it is as much a feeding trip as a transit.

How scientists track a bird that light

A geolocator is a tiny logger that records ambient light every few minutes. It does not transmit anything, so it is cheap in energy and weight, but you have to catch the bird again to read it. Day length at any moment depends on latitude and time of year, and the clock time of local noon depends on longitude, so a log of light levels can be converted into a rough daily position.

The method works like a diary that only records how bright the day was. From that, you can reconstruct a route across an ocean basin, though not the exact perch the bird chose. That coarseness is fine for a migration spanning 70,000 kilometers. It is also why the 11 recovered birds matter: each logger had to survive a year, and each bird had to return to the same colony.

For comparison, the satellite and GPS tags used on bigger animals report positions directly, which is why you will see the rest of this article lean on them. If you are curious how the satellite side of the story works, our explainer on how GPS works covers the signal timing that tag manufacturers build on.

The sooty shearwater's figure-eight across the Pacific

The sooty shearwater breeds on islands near New Zealand and Chile, then spends the rest of the year feeding across the whole Pacific. A tagging study led by Scott Shaffer, published in PNAS in 2006, put 33 archival tags on birds in early 2005 and recovered data from 19 of them. Science News summarized the result as about 64,000 kilometers a year, the longest breeding-season-to-breeding-season journey tracked electronically at the time (Science News).

The route is a figure-eight loop because the birds cross the equator twice, once heading north and once returning south. The University of California, Santa Cruz summary of the study adds an important correction to the common retelling: each tagged bird used only one of three North Pacific hot spots, off California, Alaska, or Japan, rather than visiting all of them in a single year. The same summary notes the tags weighed about 12 grams and that the birds barely fed while crossing the equator (UC Santa Cruz).

Science News reported that the birds averaged about 910 kilometers per day while crossing the food-poor waters at the equator. That pace fits the logic of the whole trip: the shearwaters do not linger where there is little to eat. They sprint across the empty equatorial water and spend most of the year at one of the three productive feeding areas.

The result is a bird that effectively skips winter. It breeds in the southern summer, then spends the northern summer feeding in the other hemisphere, then returns. The tern does something similar in the Atlantic, but along a north-south axis with a stopover in the middle. The shearwater's version is a loop that covers the whole Pacific.

The bar-tailed godwit's nonstop sprint

Tern and shearwater records are about annual distance. The godwit's record is about a different thing: the longest flight without landing. BirdLife International's species account lists three milestones for the subspecies that breeds in western Alaska and winters in New Zealand and southeastern Australia (BirdLife DataZone):

• A satellite-tagged female known as E7 flew 11,680 kilometers in just over eight days in 2007.
• A male tagged 4BBRW flew more than 12,000 kilometers from Alaska to New Zealand in 11 days in 2020.
• A juvenile tagged B6 flew more than 13,500 kilometers from Alaska to Tasmania in 11 days in 2022, which BirdLife describes as the longest continuous journey recorded for a landbird.

The 2022 flight was reported by news outlets before it had been through peer review, and researchers noted that only a handful of birds had been tracked, so it is unclear how often godwits fly that far in one go. Treat it as a documented individual record, not a species average.

Fuel, mass, and a shrinking gut

A godwit cannot refuel over open ocean, so it leaves with the tank full. BirdLife reports that fat makes up more than half of a godwit's body weight just before departure from Alaska. The account also notes that the bird's gizzard and intestines shrink to almost nothing before the flight, because digestive organs that are not in use are dead weight (it cites Piersma and colleagues, 1998).

Think of the bird as a flying fuel tank that rebuilds itself around the load it carries. The muscle and fat stay; the machinery for processing food is cut back, then regrown at the other end. BirdLife's page also notes that tailwinds help these flights reach an average speed of about 56 kilometers per hour.

The leatherback turtle's trans-Pacific swim

Some of the longest tracked journeys belong to animals that swim. A female leatherback, tagged after nesting at Jamursba-Medi beach in Papua, Indonesia, was followed by satellite for 647 days. She swam a minimum of 20,558 kilometers (12,774 miles) across the Pacific to foraging waters off Oregon, then headed back west before the signal was lost. The account, by Peter Dutton, Scott Benson, and Creusa Hitipeuw, appeared in the SWOT Report in 2008 and was reported as a sea turtle record at the time (SWOT Report via seaturtlestatus.org).

Two caveats apply. The distance is a minimum, because the transmitter stopped before the journey ended. And it is a single animal, so it shows what a leatherback can do, not what the typical female does. A later study of 135 females followed over 15 years found that western Pacific leatherbacks from Indonesian nesting sites feed in places that include the South China Sea, southeastern Australia, and the U.S. West Coast, according to Scientific American's summary of the work (Scientific American).

Mammals: the western gray whale and a wandering humpback

For mammals, two cases are worth separating because they are often confused.

The mammal record: Varvara

NOAA Fisheries describes the eastern North Pacific gray whale's yearly trip as about 10,000 miles (16,000 kilometers) round trip, and in some cases up to 14,000 miles, between summer feeding grounds in the northern Bering and Chukchi Seas and the shallow lagoons and bays of Baja California, Mexico, where calves are born, mostly from early January to mid-February (NOAA Fisheries).

The upper end of that range was demonstrated in 2015 by a team led by Bruce Mate. They satellite-tagged seven western gray whales off Sakhalin Island, Russia. Three later migrated to the eastern North Pacific. That mattered because western gray whales were once considered extinct, and their migration routes and breeding areas were unknown. One female, Varvara, left Sakhalin in November 2011, crossed the Bering Sea and Gulf of Alaska, covered 10,880 kilometers in 69.5 days to reach Baja California, spent 42 days there, and returned by a different route (10,484 kilometers in 79 days) to Sakhalin on May 14, 2012. The round trip totaled 22,511 kilometers over 172 days, which the authors described as the longest documented mammal migration (Mate et al., 2015, PMC).

The study also showed a route difference worth noting. The tagged whales moved through deep water far from shore, unlike the slower, near-shore pace usually described for eastern gray whales. That has a conservation edge: NOAA estimates fewer than 300 individuals remain in the western North Pacific population, which has not recovered the way the eastern population did after it was delisted in 1994.

The wandering humpback

In December 2024, a team led by Ekaterina Kalashnikova reported in Royal Society Open Science that a male humpback photographed off Pacific Colombia in 2013 and 2017 had been identified near Zanzibar, in the Indian Ocean, in 2022. The two sightings are separated by 13,046 kilometers of great-circle distance, which is the shortest possible path over the globe's surface and therefore a minimum. Matching came from machine-learning analysis of tail-fluke patterns in photos submitted by researchers and the public to the Happywhale database. Coverage described it as the first documented case of an adult male humpback moving between the Pacific and Indian Oceans (EWN).

Researchers suggested the trip could be linked to a changing climate or a shift in mating strategy. Another whale scientist quoted in coverage said such long movements may be less extraordinary than they look, simply because so little is known about movements between ocean basins. This is not the mammal distance record. It compares two sightings years apart, while Varvara's number comes from a continuous satellite track. For another side of whale behavior, see why whales sing underwater.

Insects: monarchs and the globe skimmer

Insects migrate with an extra constraint: a summer monarch lives only a few weeks. Its trip is a relay, not a solo marathon.

The monarch relay

The U.S. Fish and Wildlife Service reports that eastern monarchs travel up to about 3,000 miles (roughly 4,800 kilometers) from Canada and the United States to oyamel fir forests in central Mexico, at elevations of about 2,400 to 3,600 meters, a trip that often takes more than two months. The longest single-day flight recorded for a tagged eastern monarch was 265 miles. Western monarchs migrate shorter distances, about 300 to 1,000 miles, to the California coast and northern Baja California (USFWS).

The relay works because of two different lifespans. During the summer breeding season, adults live about two to five weeks, mate, and lay the eggs of the next generation. The final generation of the year does not become reproductive right away. These butterflies enter a state called reproductive diapause and can live six to nine months, which is long enough to reach Mexico, overwinter, and start the northward leg back in spring. No individual makes the whole round trip; it takes several generations of short-lived adults to complete the cycle.

The globe skimmer: a hypothesis with numbers behind it

The globe skimmer dragonfly (Pantala flavescens) is proposed to cross the Indian Ocean from India to East Africa in autumn, with a later generation returning in spring. A 2021 paper in Frontiers in Ecology and Evolution by Johanna Hedlund and colleagues tested whether that is physically possible by combining an energy model with wind trajectories. A mixed strategy of gliding and flapping would allow roughly 230 to 286 hours aloft if gliding costs about as much as resting. Simulated crossings that succeeded averaged about 127 hours in autumn and 55 hours in spring (Hedlund et al., 2021).

The authors treat the migration as a hypothesis, not a confirmed observation. Only 15.2 percent of simulated autumn trajectories and 40.9 percent of spring trajectories reached land, so the route would depend on a narrow window of favorable winds. This is why the dragonfly is not in the record table: the science supports "plausible and extraordinary," not "documented."

On land: caribou and the wolves that outrun them

Walking is expensive, which is why terrestrial records are an order of magnitude smaller. A 2019 study in Scientific Reports pooled GPS collar data from animals around the world. Led by Kyle Joly, Elie Gurarie, and Mark Hebblewhite, it found that caribou likely make the longest terrestrial migrations, with round trips above 745 miles (1,200 kilometers), measured as the straight-line distance between migration end points (National Park Service).

The study also drew a distinction that matters for this whole article. A gray wolf in Mongolia moved a total of 4,503 miles (7,247 kilometers) in a year, the most of any animal in the data set, but wolves do not migrate in a repeated seasonal circuit. Caribou own the longest migration; wolves and khulan (Mongolian wild asses) cover more ground overall. A migration record and a total-distance record are different prizes.

How migratory animals find their way

A long route is useless without navigation. Animals that cover tens of thousands of kilometers usually combine several cues, and which cues dominate differs by species and terrain. Our overview of how animals navigate on long migrations covers the broader menu; here are the best-documented systems.

A sun compass with an internal clock. The sun moves across the sky, so using it as a compass requires knowing the time of day. In 2009, Christine Merlin, Robert Gegear, and Steven Reppert showed in Science that migrating monarchs need their antennae for accurate time-compensated sun-compass orientation. Butterflies without antennae lost their group direction, while butterflies with antennae painted black (blocking light to the clocks inside) lost their orientation when the light cycle was shifted. The brain's own clock gene cycles stayed normal, so the antennal clocks appear to be the main timing source (Merlin et al., 2009, PMC). For the underlying clock biology, see circadian rhythm.

A magnetic compass for cloudy days. In 2014, Guerra, Gegear, and Reppert reported in Nature Communications that migrating monarchs also have an inclination magnetic compass (it reads the angle of Earth's field lines, not just north) that depends on ultraviolet-A and blue light between 380 and 420 nanometers. Reversing the field's inclination reversed the butterflies' heading in a flight simulator. The antennae appear to hold light-sensitive magnetosensors, and the authors suggest the compass could help when directional daylight cues are unavailable (Guerra et al., 2014, PMC). They did not test overcast skies directly, so the cloudy-day role is a proposal. For the physics behind that compass, see how magnetism works.

Smell and landmarks. Salmon do not use compasses to find their home river; they follow a chemical memory of it, as explained in how salmon find their birth river. The broader sensory toolkit is covered in how animals navigate with a magnetic sense.

Wind and ocean cues. For terns and shearwaters, the best evidence is not a specific sense but a strategy. The Egevang team concluded that terns favor productive ocean areas and use prevailing winds to reduce costs. Researchers have not pinned down exactly which cues the birds use to hold course across featureless water, and that remains an open question.

Why migrate such extreme distances at all

Food and good breeding conditions rarely peak in the same place all year. A migrant is an animal that has solved this by owning two locations, the way a farmer might own land on both sides of the equator, one with July rain and one with January rain. Staying put on either would mean a lean season. Moving between them costs energy but removes the off-season.

The cost-benefit calculation changes with body plan. For a flying bird, air is a medium that can carry you. A tern or shearwater that picks its winds can recover much of the extra distance in lower effort. A swimming animal pushes through a medium roughly 800 times denser than air, which is one plausible (untested here) reason whale and turtle records fall short of the best seabird records even though the animals are far larger. Land records are smaller again.

Calving is part of the explanation for gray whales. NOAA places their summer feeding grounds in the northern Bering and Chukchi Seas, while calves are born in the shallow lagoons and bays of Baja California. The migration therefore links a feeding ground with a nursery 16,000 kilometers or so apart by round trip. Monarchs show a different pattern: the eastern population spends the winter in cool, high-elevation fir forests in Mexico instead of staying in the north.

Common misconceptions

"Distance equals a straight line." The tern record exists because researchers stopped drawing straight lines. The tracked birds' real paths were nearly double the textbook estimate. The same warning applies in reverse to the humpback case: 13,046 kilometers is the minimum great-circle separation, and the whale's actual swimming path was almost certainly longer.

"The biggest numbers are comparable." Varvara's 22,511 kilometers covers one whale's full round trip. The humpback's number compares two sightings. The godwit's is a nonstop flight. The tern's is a typical annual total across 11 birds. Ranking these in a single list implies a precision that the data do not support.

"Longer is always more expensive." A wind-assisted detour can cost less than a shorter flight against the wind. That is the tern's strategy, and it shows why distance alone is a poor predictor of effort.

"One monarch flies the whole loop." None does. The overwintering generation lives six to nine months, but summer generations live two to five weeks, so the cycle is a relay.

"The record holders are safe." Tracking records say what animals can do, not how they are faring. NOAA's estimate of fewer than 300 western gray whales is a reminder that an extraordinary migration does not guarantee a healthy population.

The takeaway

The longest migrations are not simple feats of stamina. They are solutions to a scheduling problem: food peaks in one place, breeding conditions in another, and the winds and currents that connect them are uneven. The Arctic tern wins the annual-distance contest because it takes a long, wind-friendly S-curve between two polar summers. The godwit wins the nonstop contest by turning its body into a fuel tank, and Varvara shows that a mammal can cover more than 22,000 kilometers when the route is worth it.

The sharper lesson is about measurement. Every record in this article came from a technology that did not exist, or was too heavy to put on a small animal, a few decades ago. Each new generation of tags has more than doubled some textbook numbers, so the next record may be waiting in a species no one has yet tracked, in the same ocean we still have barely explored.

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Read next:

• Why whales sing underwater
• How birds migrate thousands of miles
• The fastest animals on Earth
• The largest single living organisms

FAQ

Q: What animal has the longest migration on Earth? A: Among animals with published tracking data, the Arctic tern. A 2010 PNAS study of 11 birds fitted with geolocators found annual round trips of about 70,000 kilometers (43,500 miles), with some individuals above 80,000 kilometers, between Greenland or Iceland and the Southern Ocean.

Q: How far does an Arctic tern fly in its lifetime? A: National Geographic's summary of the tracking study estimates more than 2.4 million kilometers (about 1.5 million miles) over a lifespan of around 30 years. That is roughly three round trips to the Moon, though lifetime figures extrapolate from one or two tracked years.

Q: What is the longest migration of any mammal? A: A western gray whale named Varvara holds the documented record: 22,511 kilometers (13,988 miles) round trip between Sakhalin Island, Russia, and Baja California, Mexico, in 172 days during 2011 and 2012. Typical eastern gray whales travel about 16,000 kilometers (10,000 miles) round trip, according to NOAA Fisheries.

Q: Is the humpback whale that traveled from Colombia to Zanzibar the mammal record? A: No. The 13,046-kilometer figure is the great-circle distance between sightings in 2013 and 2017 off Colombia and in 2022 near Zanzibar, so it is a minimum separation, not a tracked path. Varvara's 22,511 kilometers comes from continuous satellite tracking of a full round trip.

Q: What is the longest nonstop bird flight? A: A juvenile bar-tailed godwit flew more than 13,500 kilometers from Alaska to Tasmania in about 11 days in 2022, according to BirdLife International. Earlier records were 12,000-plus kilometers for a male in 2020 and 11,680 kilometers for a female in 2007.

Q: How do migratory animals navigate without landmarks? A: Most combine several cues. Monarch butterflies use a sun compass driven by clocks in their antennae and an inclination magnetic compass that needs ultraviolet and blue light. Seabirds such as terns appear to exploit prevailing winds and productive ocean areas, but the exact cues they use across open water are not settled.

Q: Does an individual monarch butterfly fly the entire migration? A: No. Summer monarchs live about two to five weeks, while the final generation of the year can live six to nine months. That long-lived generation flies south to Mexico, overwinters, and starts the northward return, which later generations finish.

Sources

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• Egevang, C., et al. (2010). "Tracking of Arctic terns Sterna paradisaea reveals longest animal migration." PNAS, 107, 2078-2081. NERC Open Research Archive
• National Geographic. "Chasing daylight: tiny trackers reveal the incredible flight plans of the Arctic tern." Link
• Shaffer, S. A., et al. (2006). PNAS. Summaries: Science News; UC Santa Cruz
• BirdLife International. Bar-tailed godwit species account. DataZone
• NOAA Fisheries. Gray whale species profile. Link
• Merlin, C., Gegear, R. J., and Reppert, S. M. (2009). Science, 325, 1700-1704. PMC2754321
• Guerra, P. A., Gegear, R. J., and Reppert, S. M. (2014). Nature Communications. PMC4090716
• U.S. Fish and Wildlife Service. Monarch butterfly. Link
• Hedlund, J., et al. (2021). Frontiers in Ecology and Evolution. Link
• National Park Service. Longest terrestrial migrations (Joly et al., 2019). Link
• Dutton, P., Benson, S., and Hitipeuw, C. (2008). SWOT Report, vol. 3. seaturtlestatus.org
• EWN (December 12, 2024). Humpback whale migration report. Link