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Great migrations

Living mass movements and climate-era range shifts: not Out of Africa and not a second Attila page. The Migration Period stays on Humans. Cards here name a driver, a season or a documented shift, and a source.

A cold dry grassland at dusk with a distant woolly mammoth and horse: a stand-in for the lost mammoth steppe, not a named bone bed

Great migrations

Mammoth steppe collapse

Not a northward flight into the Arctic: cold dry grassland from Europe to Alaska broke into forest, wetland, and tundra, and the last ranges of several giants shrank east.

Source: Stuart, Kosintsev, Higham & Lister, Nature, 2004: giant deer to ~7,700 years in western Siberia; range shifts vs Wrangel mammoths

A windswept Beringian plain with distant horses and cold haze: a stand-in for the land bridge, not a dated crossing

Great migrations

Beringian land bridge

When the sea fell, Siberia and Alaska were one plain. Horses crossed it both ways. Not every giant could.

Source: Vershinina / Librado et al., Science, 2025: Late Pleistocene horse genomes; two-way Beringian exchange, Ural-Arctic cline ~50-19 ka

An early-Holocene woodland edge with a red deer at the tree line: a stand-in for post-glacial return, not a named pollen site

Great migrations

After the ice: Europe and North America

When the ice unlocked land, trees, deer, bears, and wolves moved in: from southern refugia, and in the north from Beringia.

Source: Hewitt, Biological Journal of the Linnean Society, 1999: post-glacial recolonization of European biota; Iberia, Italy, Balkans

A blue wildebeest calf standing beside its mother on open grassland

Great migrations

Blue wildebeest

Connochaetes taurinus

Rain draws the map: more than a million animals still follow fresh grass across the Serengeti-Mara.

Source: UNESCO: Serengeti National Park (seasonal wildebeest migration)

A painted lady butterfly on a wildflower, a long-distance migrant used here as a stand-in for climate-era butterfly movement

Great migrations

Butterfly range shifts

Lepidoptera

Not one river crossing: many species have moved poleward or upslope as climates warm, and a few still fly continents.

Source: Parmesan, Nature, 1996: Edith’s checkerspot range shift with climate

Arctic terns flying over a cold northern coast: a stand-in for high-latitude bird migration, not a named colony

Great migrations

Arctic migratory birds

Terns, peregrines, shorebirds, geese: the Arctic summer is a short feast of food, and winter is spent elsewhere.

Source: Egevang et al., PNAS, 2010: Greenland Arctic terns, ~70,900 km round trip