Exceptions are an inevitable part of animal life, but often more than just annoying waste. Cot can fertilize floors and water and thus influence complete ecosystems. Kot also plays an important role in the sea – especially for seabirds that cover long distances over the water. Researchers have now observed a particularly unusual toilet behavior in Japanese striped storm divers: they facilitate themselves in strict rhythm and only during flying. But why do the birds avoid the cots when swimming on the water?
Kot is much more than an unpleasant waste product in nature: it contains nitrogen, phosphorus and other nutrients. For centuries, people have been using animal excretions as fertilizers to make fields more fertile. Kot also acts as a source of nutrients in nature – it shapes floors, promotes plant growth and can influence entire ecosystems. This is particularly well known for seabirds, the guano of which enriched in large quantities of coastal regions. But what role does it play far from the mainland – in the middle of the open sea, where seabirds spend most of their lives?
An airy toilet
In order to investigate this question, Leo Uesaka and Katsufumi Sato from the University of Tokyo Sato equipped striped storm divers (Calonectris Leutomelas) with tiny cameras. The etching rubber -grown devices were attached to the belly of the animals and directed backwards. In this way, the researchers were able to document the toilet behavior of the birds in an open ocean. In 15 animals they collected almost 200 video recordings of excretions – a unique insight into the toilet habits of these seabirds.
There was a clear pattern: the storm divers put their feces almost exclusively during the flight, often shortly after lifting off the water surface. Some birds even started for a short “toilet round” and landed again within a few minutes. This indicates that the animals deliberately avoid the cots while swimming and even accept physical exertion. “Stripe storm divers have very long and narrow wings that are well suited for gliding,” explains Uesaka. “You have to beat the wings vigorously to take off what exhausted them. This means that the risk of breaking down on the surface of the sea, the effort of the lifting predominates. There must be a good reason for this.”
Uesaka and Sato suspect that this habit keeps the birds from stirring their plumage with feces. In addition, it could help them avoid predators during the toilet, or simply be more practical: during the flight, the storm diving may be more easier than on the water.
From the intestine to the ecosystem
Also interesting: During the flight, the birds koted about every four to ten minutes. As a result, around 30 grams of feces came together every hour, which corresponds to five percent of the body mass of a storm diving. “Since the body mass of seabirds is a decisive factor for flight costs and even have a slight increase in the flight, this five percent reduction in body mass for strip storm divers, which are dependent on wind-dependent dynamic gliding,” write Uesaka and Sato. In addition, birds who have to supply their boys transport five to twelve percent of their body weight back to food to the nest per flight. Regular weight loss from Cotes could help you to stay flying.
In order to find more about the unusual toilet behavior of the storm divers, Uesaka, cameras or temperature sensors with a longer battery life plans to use in combination with GPS. They should map exactly where the seabirds give up their feces in the sea. This could also reveal more about the role of the excretions for the nutrient content of the ocean. Similar to whales, the faeces of which distribute nutrients and promotes the productivity of marine ecosystems, the excretions of large seabird populations plankton and other sea creatures could supply with nitrogen and phosphorus. “Kot is important,” emphasizes Uesaka. “But people don’t really think about it.”
Source: Leo Uesaka and Katsufumi Sato (University of Tokyo), Current Biology, DOI: 10.1016/J.CUB.2025.06.058
