Googly-eyed buoy failed to deter Danish seabirds

rotating-eyed buoy – A “looming eye” buoy named Bobby was designed to scare seabirds away from Danish fishing nets. But within weeks, researchers found that cormorants perched beside it as if it posed no threat—an outcome they say underscores how hard it is to outsmart bird behavi

A yellow buoy with rotating, googly-like eyes was meant to loom over Danish fishing nets like a predator in motion. It had a name too—Bobby—and the look was deliberate: wind-spun “eyes” that appeared to change size as the flags whipped above the water.

The plan was simple on paper. Seabirds that steal fish from fishing gear also face a deadly risk when they go after catch in longlines and gillnets. where they can get tangled and drown. And because seabirds in Denmark are protected by the European Union, any deterrent has to be harmless. The question was whether a visual scare could keep birds away.

On May 13, researchers reporting in Royal Society Open Science said the answer was no. Less than a month after Bobby was deployed, no bird seemed to care. The negative results, they say, show just how difficult it is to force birds to adopt the perspective humans are trying to mimic.

Gildas Glemarec, a fisheries scientist at the Technical University of Denmark in Kongens Lyngby, framed the stakes in blunt terms. Seabird trouble for fishermen isn’t just about birds taking food—it’s about what happens when they go after fish near passive gear like longlines and gillnets. “Birds going after fish get caught in the nets and drown,” he said.

To deter that behavior, some anti-bird designs rely on something birds already pay attention to: predators flying over them. The “Looming Eye Buoy” was built around that idea. It was a yellow buoy with a pole sticking up in the air. topped with two aluminum flags painted with small and large eyes. As the wind turned the flags, the setup was designed to create the impression that “something approaching” was closing in. “It’s to give this impression of something approaching,” Glemarec said.

The buoy was tested at pound nets off the coast of Korsør, Denmark. Those nets catch migrating garfish (Belone belone) that swim into a penned-off area where humans can scoop them out at leisure. But seabirds can scoop too. The wooden poles anchoring the nets give greater cormorants (Phalacrocorax carbo) and several species of gull an easy perch.

In the experiment, Bobby was tethered in one pound net while another net served as a control. Researchers then counted birds over time. After 46 days and more than 1,000 birds, the verdict was clear: Bobby was a failure.

At first, the buoy seemed to have some effect. Glemarec said that initially “it did end up reducing the number of birds around one pound net compared to the other.” But then the birds changed their behavior. Twenty-three days later, the cormorants appeared to learn that Bobby wasn’t a threat. They perched right beside it. “They couldn’t care less about the eye turning next to them,” he said.

That shift—from wary at first to indifferent shortly afterward—matches what other researchers say about deterrents that rely on visual cues. Sebastian Wszelaki. an environmental biologist at the Wrocław University of Environmental and Life Sciences in Poland. said birds can come to treat stationary objects like scarecrows as harmless parts of the surroundings. “Moving parts raise the perceived threat. ” he said. “but if the movement is repetitive. the birds will adapt in the end.”.

Group behavior can accelerate that adaptation. Marina Papadopoulou. who studies group behavior at the Max Planck Institute for Human Development in Berlin. Germany. argued that a “brave bird” might take risks first and then spread the lesson socially. “Maybe one individual out of five would actually be a bit more prone to risk taking,” she said. When other birds see that one bird is perched safely. for instance on a scarecrow’s head. the rest of the group can adjust faster.

For fishermen trying to protect catch, the problem is that learning can make deterrents short-lived. Wszelaki said humans have to stay on their toes. He suggested people could play bird alarm calls and deploy a robotic owl or a moving scarecrow—then vary them so birds don’t get wise. “Unfortunately. there is a lack of research that precisely determines the effectiveness of a given deterrent against specific species. ” he said. That gap is part of why he called publishing negative results so important. “That’s why publishing negative results is key,” Wszelaki said. “It helps researchers learn what not to try and saves fishermen money.”.

Back on the water, Bobby’s role has been reduced. While it didn’t work against the birds. Glemarec said the buoy sometimes ends up wearing a little Christmas hat—an image that lands softly after the hard numbers. The science. though. is sharp: if birds decide a “predator” is just another fixture. even rotating eyes won’t stop them.

seabirds cormorants deterrent fishing nets buoy scarecrow bird behavior Royal Society Open Science Denmark garfish pound nets