Each year, humpback whales (Megaptera novaeangliae) travel thousands of kilometers across the Southern Hemisphere, moving from the cold, nutrient-rich waters near the Antarctic Peninsula to warmer, tropical regions where they breed and give birth. This journey, which can be over 8,000 kilometers long, happens without the whales eating. A study by researchers from Griffith University in Australia used drone photogrammetry to track 103 whales and found that they can lose up to 36 percent of their body mass during migration, which is equivalent to more than 11,000 kg of fat per whale. This weight loss is comparable to the combined weight of two adult elephants and would be staggering for humans, similar to losing more than 30 kg in less than two months without damaging muscle or organs. To prepare for this long journey, humpback whales consume nearly 57,000 kg of Antarctic krill during the feeding season. This requires eating about 28.5 million of these tiny crustaceans to build up enough energy reserves before migrating. The study highlights a unique "feast and fast" strategy that is both extreme and regular. Humpback whales have a metabolism particularly well adapted to using fats, with adipose tissues that are denser and more energetic than those of humans. These tissues release a large amount of calories without causing deficiencies, allowing vital organs to function normally, even enabling females to give birth while fasting. The energy used during migration is equivalent to the caloric consumption of a human over more than 60 years. Despite this, the whales are able to reproduce, nurse their young, and return to Antarctica several months later to start the cycle again. However, this survival strategy depends heavily on the availability of krill, whose populations are declining due to the rapid melting of Antarctic ice and overuse of marine resources. This decline is already affecting other species that rely on krill, such as the chinstrap penguin and the Adélie penguin. For humpback whales, whose survival depends almost entirely on these large food reserves before migration, the consequences could be dramatic. If krill reserves continue to decrease, their fertility, the growth of calves, and even their ability to make the return journey could be at risk. The study, published in the journal Marine Mammal Science, shows how technology, such as drone imaging, allows for a better understanding of animals that are hard to observe directly. These data are valuable for biologists and conservation efforts, highlighting an ecosystem that is extremely sensitive to climate change.