National Geographic’s podcast ‘Overheard at National Geographic’ explores the threat that invasive zombie mice pose to Marion Island’s native seabirds and the hope that the restoration of islands such as Anacapa Island brings.

Warning: Graphic photographs. Viewer Discretion is Advised.

Marion Island is a remote, sub-antarctic island where most people would imagine humans have had no real, lasting impact. However, humans have had a drastic impact on Marion and similar islands through the intentional and unintentional introduction of invasive species.

Marion, like many islands around the world, hosts a variety of seabirds—28 species including four species of Albatross which are all globally threatened to some extent. Thomas Peshak, a National Geographic Photographer, visited Marion a few years back and although he had heard of the threat that invasive mice posed to these species, he could have never imagined what he was about to see.

All of a sudden in this landscape of black and green and gray there is this red that pops out at you all of a sudden. And you’re just going, “Well, what is that?” You come around this boulder and you are literally looking at a bird that has been scalped. The entire back of its head and the entire neck has been eaten away.And that’s how you find the gruesome evidence of one of the most critical conservation crises that are facing seabirds.” explained Peschak.

The culprit—invasive mice.

Invasive mice were introduced to Marion by seal hunters in the 1800s and for almost two centuries the cold, harsh winters kept the population at a low density allowing seabirds to thrive. In the early 2000s, the winters on Marion began to get warmer and more mice would survive through winter. Without the summer food sources, mice turned to seabirds which have never evolved any defense responses to mice making them susceptible and evolutionarily naive.

Luckily, conservationists know exactly how to restore Marion—remove invasive mice. Although this project has its own set of challenges, it is a solution that has been proven on hundreds of islands around the world. Holly Jones, a professor at Northern Illinois University who studies the impact of invasive species removal on islands, explained:

..there’s no silver bullet in conservation. But if there was one, invasive mammal eradication on islands would be it.

Jones has been able to see first hand how an island can be transformed through the removal of invasive species. On Anacapa Island, where Island Conservation and our partners removed invasive rats in 1999, Holly recalls the dramatic recovery saying:

In the case of the Anacapa Island rat eradication. Birds stopped just being limited to sea caves and they started sort of nesting in other places. And birds that had never even been documented nesting on the island started nesting on the islands.”

One day Marion Island will be free of invasive mice and will have the chance to recover as Anacapa and other islands around the world have due to the removal of invasive species.

Listen to the Overheard podcast:

Featured photo: A Wandering Albatross near Port Fairy, Australia. Credit: Ed Dunens
Source: Overheard National Geographic