In Homer’s “Odyssey,” the floundering protagonist is famously offered a protective garment by a sea goddess who appears in the form of a bird after he is shipwrecked.

What role this character might have in the upcoming Christopher Nolan blockbuster remains to be seen, but seabirds have long served as signifiers of the connection between land and sea in literature.

Lost sailors are encouraged by the appearance of birds on the horizon, indicating the presence of terra firma. The appearance of an albatross heralds good luck In the 1798 poem “The Rime of the Ancient Mariner” — and its slaughter represents a major moral error. In the mythologies of some cultures, seabirds are the reincarnation of drowning victims.

In reality, seabirds follow ships, particularly fishing boats, out of pure pragmatism. They feed on human scraps — garbage or discarded catch — or snag the fish churned up by the boat’s passage.

A new study by a Japanese citizen scientist published in the journal PeerJ in May describes the proclivity of brown boobies (Sula leucogaster) for the latter and sheds new light on their tendencies to follow non-fishing vessels.

Citizen scientist Ryota Hayashi documented these relatives of gannets — and more distantly, cormorants and darters — following a passenger ferry in the Ogasawara Islands, a subtropical archipelago that is part of Tokyo but is roughly 1,000 kilometers south of the bright lights of Shinjuku and Shibuya.

“When following the ferry, the birds appeared to be targeting flying fish that were flushed from the water by the vessel,” says Hayashi, who works in research and development for engineering consulting firm Nippon Koei. “Under natural conditions, they may also feed on other small schooling fish, such as sardines and related species.”

The boobies typically followed the ferry on its outbound journey from the island of Hahajima, where their nesting colony is located. They would fly out to meet it on its inbound journey.

“In April, in the early breeding season, their numbers are still low and the number of individuals using the ferry is limited,” adds Hiroyuki Tanoi, who researches seabirds in Japan and runs a website on the subject. He was not involved in the study. “Conversely, in August, as the chicks grow and more food is required, the number of individuals using the ferry increases.”

Hayashi notes that more research is needed to determine the nature of the birds’ ferry-following behavior.  

“At present, we do not know how brown boobies detect vessel movements or how they learn that ferries can provide feeding opportunities,” Hayashi notes. “They may learn from their parents, or they may observe and imitate more experienced individuals.”

Japanese fishers once followed birds such as brown boobies in order to locate fish. The Japanese name for the brown booby is katsuo-dori, a reference to skipjack tuna (katsuo), long a staple of Japanese cuisine. Hayashi says this is largely a technique lost to time, however — more sophisticated technologies have supplanted what was once a natural indicator of the sea’s bounty.

Still, boobies and other seabirds remain highly attuned to human activities at sea worldwide. A study of Peruvian boobies (Sula variegata) found that 20% of birds to which GPS trackers and video cameras had been attached followed a large fishing fleet, engaging in the same behavior as the birds in Japan.

Hayashi’s paper builds on a growing citizen science movement, both nationally and globally.

Initiatives such as the Monitoring Sites 1000 project launched by Japan’s Environment Ministry and several nonprofits encourage citizen scientists to report their observations, contributing to a greater understanding of the country’s biodiversity. A June 2025 study published in Nature Sustainability that outlined how human depopulation may lead to biodiversity loss included findings from some 5,700 citizen scientists — a testament to Japanese enthusiasm for conservation.

Some, like Hayashi, have taken their own initiative.

As he enthusiastically points out in the paper, citizen scientists can offer “research that begins with the curiosity and discoveries of citizens themselves.”