The feces of Adélie penguins are turning pink, a phenomenon linked to changes in their diet due to environmental factors. Researchers have used satellite images to monitor penguin guano, providing insights into the impact of climate change on the Southern Ocean's food web. Adélie penguins, which are among the most numerous predators in the Southern Ocean, feed in the ocean and nest on rocky outcrops around the Antarctic continent. Their colonies, often consisting of hundreds of thousands of nesting birds, produce large amounts of guano that are easily identifiable from space, thanks to NASA's Landsat satellites. A multidisciplinary team of researchers, led by Casey Youngflesh, an assistant professor of biological sciences at Clemson University, used thousands of satellite images dating back to the 1980s to study penguin guano traces. The goal was to determine the diet of these birds and its evolution based on environmental changes. The study found that when a colony is surrounded by abundant sea ice, Adélie penguins tend to eat more small fish, while in areas with less sea ice, they rely more on krill, which have a pink exoskeleton that penguins do not fully digest, giving their guano a pinkish tint. The method involves analyzing the color of the guano and establishing a link between that color and the proportion of krill in the penguins' diet. Researchers collected penguin guano from several locations and used a spectrometer to determine the color of each sample as a satellite would perceive it. They also analyzed the composition of the guano using tools from environmental chemistry to determine the diet responsible for this color. These data, combined with statistical modeling, allowed the researchers to determine what penguins eat based on the color of their guano as observed by satellite. The study found that penguins eat different foods depending on the regions of the Antarctic continent and that their diet varies both throughout the year and from year to year. Since the 2010s, sea ice has experienced a spectacular decline in Antarctica, with several years recording new historical records for minimum coverage. Less sea ice means fewer fish, which is bad news for penguins: Adélie penguin chicks are generally heavier when fed fish rather than krill. Moreover, heavier chicks have a greater chance of surviving to adulthood. The research also revealed that in regions where penguins consume less fish, their numbers have decreased over the last few decades across the species' entire range. Conversely, penguin colonies that consume more fish have a greater chance of remaining stable or expanding. The widespread retreat of sea ice is expected to continue in the future, and Adélie penguins are also facing increased competition from other marine species and humans for access to fish and krill. In the Antarctic Peninsula region, populations of baleen whales, which primarily feed on krill, have significantly increased since the end of commercial whaling several decades ago. At the same time, gentoo penguins have expanded their range southward toward Antarctica as the climate warms, increasing the number of predators hunting in these waters. Bottom trawlers are also catching large amounts of krill destined for fish feed and human dietary supplements, which could exert additional pressure on Adélie penguins in these regions. A satellite discovered four new emperor penguin colonies in Antarctica. The information provided by satellites is particularly valuable for isolated and hard-to-reach regions such as Antarctica. Other methods of collecting these data would require considerable resources in terms of personnel, planning, travel, and survival logistics. As satellite technologies continue to improve, with higher resolution, shorter intervals between image captures, and new sensors for data collection, new opportunities are opening up for researchers to fundamentally transform the way they monitor certain wild species, providing essential information on the evolution of the world and on how humanity could adapt to these changes.