The largest colony of royal penguins in the world, located on Pig Island in the Crozet archipelago—part of the French Southern and Antarctic Territories (TAAF)—has seen a dramatic decline in its population over 35 years. According to a satellite analysis conducted by the French National Center for Scientific Research (CNRS), the colony has lost 88 percent of its breeding pairs. Once home to about 500,000 pairs, the population dropped to around 60,000 pairs by 2015. This decline began in the late 1990s, following a climatic anomaly linked to the Indian Ocean dipole in 1997. This event may have disrupted local fish populations, forcing penguins to travel further to feed their chicks, which likely impacted their survival and breeding success. The study, published in Antarctic Science in July 2018, noted that Pig Island is a small island, measuring just 67 square kilometers, and has no permanent human residents. The name "Pig Island" dates back to the 1820s, when sealers brought pigs to the island for food, though what happened to the pigs is unknown. Researchers, including Henri Weimerskirch from the Center for Biological Studies of Chizé (CNRS/University of La Rochelle), used satellite images to track the decline of the penguin colony. They observed that vegetation has started to spread into areas that were once occupied by penguins, possibly altering the habitat. A new, smaller colony of about 17,000 breeding pairs has been identified, but it only partially makes up for the loss. Researchers are considering several possible factors that could have contributed to the decline, including environmental changes, the presence of introduced predators like cats and mice, and diseases such as avian cholera, which have affected other bird species in the region. However, no single factor has been identified as the main cause of the large-scale decline. The TAAF has launched a scientific mission to investigate the reasons behind the decline. Initial findings suggest that penguins on Pig Island may feed in different locations compared to those on nearby Possion Island. Further research, including isotope analysis of blood and feathers, is needed to confirm these findings and better understand the penguins' behavior and the environmental factors affecting them.