How many km does an Arctic tern fly on its average annual round-trip migration between the Arctic and Antarctica? (1 km ≈ 0.6 mi)

Answer

70,900 km

That's nearly twice around the planet every year — the longest migration of any animal. Over a 30-year lifespan, one tern flies about 2.4 million km, the equivalent of three round trips to the Moon.

Source: Egevang et al., PNAS (2010)