Every year, humpback whales in the southeastern Pacific make a long and difficult journey. They travel up to 10,000 kilometers from Central and South America to their feeding grounds in Antarctica. But how do they know when it’s time to leave? According to new research, these whales rely on both real-time changes in their environment and long-term memories of past ocean conditions to time their migrations. The study, led by scientists from McGill University , used eight years of satellite tracking data collected between 2009 and 2016. The team tracked 42 humpback whales tagged near Costa Rica, Panama, and Ecuador. By following the whales’ movements southward to Antarctica, the researchers hoped to understand what cues triggered their annual migration . Whales use memory to time their journey The study revealed that whales respond to local cues such as sea surface temperature and food availability. But they don’t rely solely on current conditions. They also seem to remember when food was most abundant in the Southern Ocean during previous years. That memory, combined with what’s happening around them, helps them decide when to go. “They seem to know that changes happening in their immediate environment are linked to conditions thousands of kilometers away,” said Professor Virginie Millien. “This allows them to fine-tune their migration, so they arrive just as their food supply peaks.” Krill , a small crustacean, is the whales’ main food source in Antarctica. Each year, krill populations bloom during a specific seasonal window. For centuries, whales have timed their migration to match this pattern. But that rhythm is now being disrupted. Can whales keep up with climate change? Warmer oceans and changes in sea ice are beginning to shift the timing of the krill bloom. Even though whales are adjusting their departures, climate change may be moving […]