Officials plan to "bomb" invasive mice that are eating seabirds alive

Nestled in the sapphire-blue expanse of the Indian Ocean, around 2,000 kilometers southeast of Cape Town, sits a remote island. This far-flung location, known as Marion Island, is where an unnerving drama is unfolding – mice are feasting on seabirds, particularly the albatrosses.

Seabirds under threat from mice

Marion Island is a key nesting ground for some of our planet’s most significant seabirds, including the magnificent wandering albatross.

A whole quarter of the world’s population of these mighty birds prefers this Indian Ocean island as their nesting abode. But now, these creatures are under threat from an unexpected source.

Hordes of house mice, outlandishly oblivious to the natural pecking order, are preying on these majestic birds by nibbling on their eggs and, shockingly, the adult birds themselves.

This reality, as grisly as it sounds, was confirmed by leading conservationist Mark Anderson during a meeting of BirdLife South Africa.

Impact of climate change on seabirds

Climate change has a big impact on seabirds, mainly by messing with their food supply and breeding habitats. As ocean temperatures rise, the distribution and abundance of fish and other marine life that seabirds depend on for food change too.

When these prey species move or decline, seabirds have a tougher time finding enough to eat. This can lead to lower breeding success, as adult seabirds might struggle to gather enough food for their chicks.

Plus, extreme weather events like storms and heatwaves can wipe out nesting sites and make it harder for seabirds to raise their young. On top of that, climate change also messes with their migratory patterns and breeding cycles.

Changes in sea ice cover, rising sea levels, and habitat loss push seabirds to change their usual migration routes and breeding spots.

These shifts can create crowded nesting areas or lead to unsuitable breeding conditions, adding more stress to seabird populations.

Local seabird species threatened

“These mice, for the first time last year, were found to be feeding on adult Wandering Albatrosses,” stated Anderson, who also serves as the CEO of BirdLife South Africa.

The confrontation between mice and birds is turning the tranquil Marion Island into a stage for an ongoing battle.

A disturbing scene: scores of seabirds left bloodied, some with flesh chewed off their heads. As chilling as these visuals are, they do underscore the urgency of the situation.

Out of the 29 species of seabirds breeding on the island, 19 are threatened with local extinction, according to the Mouse-Free Marion Project.

Seabirds and invasive mice

The birds, having evolved without terrestrial predators on the island, simply do not know how to react to the relentless mouse attacks.

“Mice just climb onto them and slowly eat them until they succumb,” said Anderson. The sad, slow process of dying can take days for a bird. “We are losing hundreds of thousands of seabirds every year through the mice.”

Mouse-Free Marion Project

Enter the Mouse-Free Marion Project, one of the world’s most pivotal bird conservation efforts. This ambitious project aims to deploy helicopters to disperse (or bomb) 600 tons of rodenticide-laced pellets over the island. Funding is still underway, with about a quarter of the $29 million required so far raised.

The strategy is to strike in winter 2027 when the mice are most famished and the summer-breeding birds are mostly away. However, the success of this operation lies in the precision of covering every inch of this 25-kilometer-long and 17-kilometer-wide island.

“We have to get rid of every last mouse,” emphasized Anderson. “If there was a male and female remaining, they could breed and eventually get back to where we are now.”

Consequences of climate change

These rodents weren’t always this menacing. So, what changed? First introduced to the island in the early 1800s, house mice had a limited diet of plants and invertebrates.

But warmer temperatures due to climate change have allowed them a longer breeding period, leading to their explosive population growth.

In their search for food, the mice have turned their attention to the easy pickings on the island – the birds. The island’s ecosystem continues to bear the brunt of these altered dynamics.

History of eradication

Marion Island has been down a similar road before. In the mid-20th century, cats were introduced to control the burgeoning mouse population.

However, the feline population exploded, devouring a staggering 450,000 birds annually. It was only in 1991 that the last of these predatory cats was removed, in what was then a successful eradication project.

Saving the seabirds from mice

The current situation requires an even bigger commitment to securing the future of Marion Island’s seabirds. But can history repeat itself? Only time will tell.

The saga of Marion Island serves as a potent reminder of how intertwined we are with our environment and the fragile balance that exists within our ecosystems.

It’s clear that even the slightest tweaks in the natural order can lead to consequences far beyond what we might initially perceive. Here’s hoping the Mouse-Free Marion Project can usher in a new era of harmony between the island’s birds and their habitat.

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