Humpback whales undertake one of the longest migrations of any mammal on Earth, traveling approximately 16,000 miles roundtrip between their feeding and breeding grounds. They arrive in Antarctic waters around November as the Southern Hemisphere spring begins, when the ice starts to break up and krill populations become abundant. The whales remain in these nutrient-rich waters through the austral summer, feeding intensively on Antarctic krill to build up fat reserves. Peak whale populations occur during December and January when conditions are most favorable.
The return migration begins in February and March as daylight decreases and water temperatures drop. Humpbacks leave Antarctic waters and head back to their breeding grounds in warmer tropical and subtropical waters off South America, Africa, Australia, and other regions. This remarkable annual migration is driven by the need to exploit the seasonal abundance of krill in the Antarctic, while also requiring breeding populations to move to warmer waters for mating and calf rearing. Climate change and shifting ice patterns are beginning to affect the timing and routes of these migrations.