Poo is big business in the open ocean. It’s a vital source of nutrients for many aquatic plants, and helps sequester vast amounts of carbon from the atmosphere. But studying poo and pooing behavior in the ocean isn’t easy.
Lucky for us, then, that Japanese researchers reviewed nearly 36 hours of video footage to determine how a common seabird defecates.
How Seabirds Poop to the Rhythm
In a new study published in Current Biology, a team from the University of Tokyo attached video cameras to the bellies of 15 streaked shearwaters (Calonectris leucomelas), seabirds that inhabit the Pacific Ocean, to monitor their defecation practices.
The team found that the birds have a tight routine: they poop at least once every 10 minutes and almost never while floating on water. The team suspects this regular behavior keeps the seabirds’ feathers clean, while also acting as a helpful fertilizer for the ocean below.
Leo Uesaka, an atmosphere and ocean researcher at the University of Tokyo and study coauthor, didn’t intend to become a full-time bird poo videographer. Instead, he wanted to record how the streaked shearwater takes off from the ocean’s surface.
“Streaked shearwaters have very long and narrow wings, good for gliding, not flapping,” said Uesaka in a press release.
This physiology means the birds must expend a lot of energy to take off. Despite this, Uesaka noticed that the birds would sometimes take off for less than a minute. When they did so, they would defecate and then return to the sea. He also observed that flying birds defecated regularly, maintaining a rhythm of defecation every four to 10 minutes, regardless of how recently they had eaten.
“I thought it was funny at first, but it turned out to be more interesting and important for marine ecology,” said Uesaka.
Read More: Ants Do Poop and They Even Use Toilets to Fertilize Their Own Gardens
Studying Bird Poop
Uesaka recorded hours of footage from the streaked shearwaters and noted 195 excretion events at an average rate of 5.2 poos per hour. Only one of these happened while the bird was floating.
“This means the risk of excreting on the sea surface outweighs the effort to take off. There must be a strong reason behind that,” said Uesaka.
They theorized that airborne defecation helps keep the birds’ feathers clean, allows them to avoid predators attracted to the smell of poo, such as sharks or seals, or might make it easier to push out feces.
Regular Pooping Helps the Ocean
While the exact reason why shearwaters poo from the sky is unclear, Uesaka’s research has demonstrated that it is likely an essential contributor to the ocean ecosystem. The birds’ feces size and regularity mean that they excrete 30 grams every hour — roughly 5 percent of their total body mass.
There are an estimated 424 million members of Procellariiformes, the biological taxon that includes shearwaters. This means these ocean birds poo six Titanic’s worth of feces into the ocean every single day.
Previous research has demonstrated how seabird droppings fertilize coastal land and water with their high nitrogen and phosphorus content. But shearwaters are pelagic, meaning that they spend most of their lives on the open ocean. While their poo is likely to be an essential contributor to plankton and other feces-eating marine critters far from shore, it’s only through detailed analysis of how birds defecate that we can calculate how significant this contribution is.
Uesaka wants to further his research by using GPS-linked cameras to build a map of seagull poo across the ocean to fully map how feces fertilize our waters.
“Feces are important,” he summed up. “But people don’t really think about it.”
Read More: Ocean Gardeners: Why Whale Poop Matters Now More Than Ever
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