Why do Gray Whales Migrate?
Gray or grey whales are baleen whales which migrate yearly from the cold Arctic to the warm Mexican lagoons between feeding and breeding grounds. They can grow up to 16 meters (52 ft) and weighs 36 tons and can live in a lifespan of 50-60 years.
Gray whales migrate farther than any mammal here on earth. Each year they travel almost 10,000 miles from north to south and back. Gray whales start migrating during October. They leave the Bering and Chukchi seas, their feeding grounds up north. By fall, they swim down south to their breeding grounds in Mexico and Baja California. They move south to breed in the warm, shallow lagoons along the coast of Mexico. The journey downwards will take them at least 2-3 months. After their mating and calving season, they return up north to their feeding grounds during the late winter and spring which is by mid-February to early June.
But not all of them migrate down south. Some individual gray whales can still be found swimming at the coasts of Oregon, California, Washington and British Columbia all year round.
During the migration period, the first whales to arrive are the pregnant mothers who seek the shelter of the lagoons where they will give birth to their calves. After them are those single female whales seeking mates. By that time, the breeding grounds will be filled with birthing, nursing and breeding gray whales.
By mid-February and March these gray whales will now begin their journey back north. The first ones to leave the lagoon are the males and females without calves. The last to depart are the nursing and pregnant mothers together with their calves. They will only leave the breeding ground when their calves are ready for the journey. Sometimes these mothers will stay with their calves in the lagoon up until May.
In conclusion, these gray or grey whales travel north to the cold waters to feed while they travel south to warm waters to breed and give birth. They do this migration routine all year long.