The River of Raptors

Every fall, millions of hawks fly south for the winter, and most of them barely flap. They ride thermals, columns of warm air rising off sun heated land, circling upward inside one and then gliding to the next. It is the cheapest way to travel a continent.

Why This Is Happening

But thermals do not rise over cool water. When the migration reaches a coastline, the birds refuse the sea crossing and pile up along the shore. Where the land narrows, they compress into a single flying stream. Stand under it and the sky fills, hour after hour, with birds flowing past like water. The local name for it is the River of Raptors, and the greatest one on Earth runs through Veracruz.

Veracruz sits on Mexico's Gulf coast, about four hours east of Mexico City. To the west rises the wall of the Sierra Madre. To the east lies the Gulf. Between them the coastal plain narrows to a corridor, and every fall the continent's raptors pour through it. Broad winged hawks, Swainson's hawks, turkey vultures, falcons, eagles: four to seven million birds a season, counted by Pronatura Veracruz since 1991 from two permanent stations at Cardel and Chichicaxtle, just north of the city.

The numbers are hard to picture until you stand there. Single days have topped 700,000 raptors. On peak days the counters log 100,000 birds an hour. The flight runs strongest between 1 and 3 PM, when the thermals stand tallest.

When to Go

Early to mid October is the climax, and it arrives in waves. Broad winged hawks, close to two million of them, run from mid September into the first week of October. Swainson's hawks, around 300,000, own the first two weeks of October. Turkey vultures, another million and a half, run late September into late October. October is when the waves overlap and the river runs fullest.

The physics is the same wherever thermals meet water, so the phenomenon repeats on other continents on different schedules. At Hawk Ridge above Duluth, Minnesota, tens of thousands of broad winged hawks climax in mid September, and October belongs to the eagles: bald eagles, red tailed hawks, goshawks. At Batumi, on Georgia's Black Sea coast, the third largest raptor migration on the planet moves honey buzzards in late August and steppe buzzards and eagles from late September into early October. Same river. Different month.

Fly to Veracruz city, drive north to the count sites, and look up. October is now.