In the vast expanse of the South Atlantic Ocean, a tiny speck of volcanic rock called Gough Island holds a dark secret. It's a story that unfolds in the dead of night, when sleepy albatross chicks are left vulnerable to an unlikely predator: the humble house mouse.
Jaimie Cleeland, an Australian marine ecologist, spent a year on this remote island, witnessing a chilling reality. In just one week, she saw 15 albatross chicks fall victim to these diminutive invaders. It's a tale that challenges our perceptions of the natural order and highlights the intricate, often devastating, consequences of human interference.
A Dream Job's Dark Side
Cleeland's work on Gough Island reads like an adventure script. One day, she's operating a crane to transport scientists up a treacherous cliff, and the next, she's navigating a supply barge in the icy waters of Antarctica. But beneath the surface of this dream job lies a haunting reality.
She recalls finding a Tristan albatross with a fishing hook lodged in its beak, a stark reminder of the threats these majestic birds face. And then there was the chick that somehow ended up in Rio, its stomach filled with a mysterious cloth. These incidents are a window into the complex and often tragic lives of these seabirds.
The Unseen Threat
The Tristan albatross, with its impressive three-meter wingspan, is a giant among seabirds. Yet, on Gough Island, it faces a formidable foe in the form of regular house mice. These tiny creatures, brought to the island by sailors in the 19th century, have thrived without natural predators, growing larger and more aggressive over generations.
The mice attack at night, when the chicks are drowsy and their parents are away feeding. Over the course of a few hours, they inflict small wounds that worsen until the chick succumbs. Cleeland describes the process as a slow, agonizing death, with the first mouse appearing and the chick dying within an hour.
The Scale of the Disaster
The impact of these mouse attacks extends far beyond the unfortunate chicks. Ecologist Anthony Caravaggi's research estimates that mice on Gough Island are responsible for the death of approximately two million seabird eggs and chicks annually, including those of albatrosses, petrels, shearwaters, and the island's endemic bunting and moorhen.
Climate change exacerbates this crisis. Historically, colder winters kept the mouse population in check, but milder winters allow more mice to survive, and the chick-attacking behavior seems to spread through the population at an alarming rate.
Even the Adults Aren't Safe
It was once believed that adult albatrosses were too large to be threatened by mice. However, recent studies have shattered this assumption. Marine biologist Maëlle Connan and her colleagues documented the first confirmed cases of mice killing fully grown adult Tristan albatrosses on Gough Island and adult wandering albatrosses on nearby Marion Island.
On Gough, two Tristan albatrosses brooding small chicks were found with characteristic wounds in March-April 2021, and one died eight days later after its wound became infested with blowfly larvae.
A Cautionary Tale
Gough Island serves as a stark reminder of the fragility of our ecosystems and the devastating impact of introduced species. It's a story that should give us pause, even if we're thousands of kilometers away. The Tristan albatross pairs spend years courting before settling down, and their devotion to their chicks makes the losses all the more heart-wrenching.
Cleeland's year on Gough Island wasn't just about documenting death; it was about witnessing a catastrophe and trying to prevent it from becoming irreversible. It's a battle against time, and one that conservationists refuse to give up on.
