The gray whale migrates each year from Arctic feeding grounds to Baja California’s warm lagoons. In the eastern Pacific, whales begin heading south in autumn from the Bering and Chukchi seas, traveling along the coasts of Canada, the United States, and Mexico.
The journey can cover 8,000–11,000 kilometers one way. Pregnant females arrive early at Baja California’s protected lagoons, where they give birth, while other whales use the area for mating and nursing. Calves benefit from the lagoons’ relatively calm, warm waters before the long trip north.
Gray whales usually begin returning north in late winter and spring, with mothers and young calves among the last to leave. Humpback whales also migrate seasonally, which can cause confusion, but the Arctic-to-Baja route is the classic migration associated with gray whales. The round trip is among the longest regular migrations known for any mammal.