Japan - August 17, 2025 Researchers studying streaked shearwaters (Calonectris leucomelas) on Japan’s desert islands uncovered a surprising habit: the seabirds only poop while flying, never while floating on water. Reporting in Current Biology on August 18, the team found that the birds relieve themselves every 4 to 10 minutes, a routine that may help them stay clean and fertilize the ocean below. “I was studying how seabirds run on sea surface to take off,” said Leo Uesaka, lead author from the University of Tokyo. “While watching the video, I was surprised that they dropped feces very frequently. I thought it was funny at first, but it turned out to be more interesting and important for marine ecology.” Seabird droppings are rich in nitrogen and phosphorus, nourishing coastal waters and soil. While their impact on land is well known, little is understood about how seabird feces affect the open ocean. With an estimated 424 million shearwaters and related species, their droppings could supply nutrients to plankton and marine life far from shore. Using small backward-facing cameras attached to 15 shearwaters, Uesaka recorded nearly 200 defecation events. The birds almost always pooped while flying, often immediately after takeoff. Some even took off solely to relieve themselves, returning to the water within a minute. “There must be a strong reason behind that,” Uesaka noted, suggesting it may prevent fouling feathers, avoid predators, or make excretion easier. The team calculated that the birds excrete about 30 grams of poop per hour—around 5% of their body mass. Uesaka plans further studies with GPS and longer-lasting sensors to map where the birds release their droppings and better understand their role in marine ecology. “Feces are important,” Uesaka said. “But people don’t really think about it.”