Which land animal has the longest migration? Biologists have long suspected that caribou journey the farthest on their annual round trip, but hard evidence was lacking.

Kyle Joly at the Gates of the Arctic National Park & Preserve in Fairbanks, Alaska, and an international team of researchers who track mammals decided to settle the question by pooling their own findings and data collected by other scientists. They found that caribou (Rangifer tarandus) do indeed migrate the farthest between their summer and winter ranges, with some herds covering more than 1,200 kilometres in a round trip. Caribou beat wildebeest, bison, pronghorns, Mongolian gazelles and Burchell’s zebras for the title of the mammal with the longest migration.

But the prize for most kilometres covered in a year went to another mammal: the grey wolf (Canis lupus). The absolute champion was a male from Mongolia that covered a jaw-dropping 7,247 km in a single year. In general, predators covered more ground than their prey.

Sadly, human manipulation of landscapes has broken or truncated many ancient migrations. The researchers call for the conservation of these epic animal journeys, as well as the species that undertake them.