Some animals do not so much move house as cross whole oceans and continents. Five of those journeys are collected here, each described from research papers and government agency pages, with the figures kept as those sources give them. Distances appear in the units each source uses, and most describe tracked animals or particular populations, not every individual of a species.
1. The Arctic tern: a bird under 125 grams, tracked over 80,000 km a year
A 2010 study in the Proceedings of the National Academy of Sciences (PNAS) opens with the Arctic tern’s size: under 125 g. Researchers fitted 11 terns with 1.4 g geolocators and followed their travels between breeding grounds in the boreal and high Arctic and the Southern Ocean. Some individuals covered more than 80,000 km in a year.
The tracking also turned up a previously unknown stopover area in the North Atlantic, used by birds from Greenland and Iceland colonies. Birds from the same colony took one of two southbound routes, along either the African or the South American coast. The authors report that the terns target regions of high marine productivity and use prevailing global wind systems to reduce flight costs. Eleven birds is a small sample, and 80,000 km is the figure for some individuals rather than an average for the species.
2. Bar-tailed godwits: across the Pacific without a landing
These shorebirds breed and spend the non-breeding season in places separated by the vast central Pacific Ocean. A 2009 paper in Proceedings of the Royal Society B followed their southward flights by satellite. Seven females carrying surgically implanted transmitters flew non-stop between 8,117 and 11,680 km, and the flights lasted from 6.0 to 9.4 days. Two males with external transmitters flew non-stop for 7,008 to 7,390 km, taking 5.0 to 6.6 days.
The authors describe these flights as establishing “new extremes for avian flight performance”. They also propose, and the wording is theirs, that the route may work as a wind-assisted passage relatively free of pathogens and predators. Nine tracked birds make this a small study, though a striking one.
3. Humpback whales: from feeding grounds to warm calving waters
NOAA Fisheries says humpback whales have one of the longest migrations of any mammal on the planet, with some populations swimming 5,000 miles from tropical breeding grounds to colder, more productive feeding grounds. In the North Pacific, some whales travel from Alaska to Hawaii, and NOAA states they can complete the 3,000 mile trip in as few as 28 days.
The feeding side of the year is just as inventive. NOAA describes “group coordinated bubble net feeding”, which involves using curtains of air bubbles to condense prey before the whales lunge up through the net. It also reports that the species is increasing in abundance throughout much of its range, with a final whaling moratorium in effect since 1985, while still facing threats such as entanglement in fishing gear and vessel strikes.
4. Leatherback turtles: the ocean-crossing champions among sea turtles
The leatherback is the largest turtle in the world, and NOAA Fisheries says some swim over 10,000 miles a year between nesting and foraging grounds. Western Pacific leatherbacks swim from tropical nesting beaches, primarily in Indonesia, Papua New Guinea and the Solomon Islands, to foraging grounds off the United States coast. NOAA calls this one of the greatest migrations of any air-breathing marine animal: a nearly 7,000-mile trans-Pacific journey that takes 10 to 12 months.
The same page notes that leatherbacks can dive to approximately 4,000 feet and eat soft-bodied open-ocean prey such as jellyfish and salps. NOAA lists leatherbacks as endangered under the Endangered Species Act and reports that Western Pacific populations have declined by more than 80 percent.
5. Monarch butterflies: a journey shared between generations
The US Forest Service calls the monarch the only butterfly known to make a two-way migration as birds do. Some fly as far as 3,000 miles to reach their winter home. They can travel between 50 and 100 miles a day, and the journey can take up to two months. The farthest-ranging monarch recorded travelled 265 miles in a single day.
The eastern population overwinters in 11 to 12 mountain areas in the States of Mexico and Michoacan, roosting in oyamel fir forests at 2,400 to 3,600 metres. Tens of thousands can cluster on a single tree, though each butterfly alone weighs less than a gram. The Forest Service adds that the generation flying south has never been to Mexico before, and that successive generations make the journey north.
The bottom line
Five very different animals, each with a journey that the sources measure in thousands of kilometres or miles: a seabird weighing under 125 g, a shorebird, a whale, a turtle and a butterfly. The figures come from tracked individuals or particular populations, from different years and different methods, so they are records of what was measured, not rankings. The pages listed below hold the full details.
Sources
- Tracking of Arctic terns Sterna paradisaea reveals longest animal migration, Proceedings of the National Academy of Sciences, 2010 (pubmed.ncbi.nlm.nih.gov)
- Extreme endurance flights by landbirds crossing the Pacific Ocean: ecological corridor rather than barrier?, Proceedings of the Royal Society B, 2009 (pubmed.ncbi.nlm.nih.gov)
- Humpback Whale, NOAA Fisheries, read 25 October 2026 (fisheries.noaa.gov)
- Leatherback Turtle, NOAA Fisheries, read 25 October 2026 (fisheries.noaa.gov)
- Monarch Butterfly Migration and Overwintering, US Forest Service, read 25 October 2026 (fs.usda.gov)