The news from South Africa’s CAPE TOWN reports that a colony of mice, unknowingly brought to a remote island close Antarctica two centuries ago, is now multiplying rapidly due to changes in the climate. This has led to severe consequences such as the destruction of seabird populations and significant damage to the reserve’s one-of-a-kind range of wildlife.

Currently, conservationists have devised a strategy to eliminate a large number of rodents. This plan involves utilizing helicopters and extensive amounts of poison, approximately hundreds of tons, to be dispersed over the entire 115 square miles (297 square kilometers) of Marion Island in order to achieve the desired outcome.

If at least one pregnant mouse manages to survive, their high reproductive rate could render all efforts futile.

The Marion Island Mouse-Free Project is a major initiative for pest management, with a focus on promoting a healthy ecology in the uninhabited regions of South Africa and the broader Southern Ocean. If successful, it will be the largest eradication effort of its kind.

The island is a habitat for almost 30 species of birds, including globally significant populations. It also boasts a rare undisturbed environment for wandering albatrosses and numerous other species, known for their 10-foot wingspans.

Without interruption, at least until uninvited house mice arrived on ships used for seal hunting in the early 1800s, bringing the island’s first predators that are mammals.

According to Dr. Anton Wolfaardt, the manager of the Mouse-Free Marion project, the past few decades have been particularly damaging due to the presence of mice. He noted a significant increase in their population, attributing it to the effects of climate change. The once cold and windswept island has become warmer, drier, and more welcoming to the mice.

Wolfaardt stated that this species is likely one of the most accomplished in the animal kingdom, as they have spread to various locations. However, on Marion Island, their reproduction period has been prolonged, leading to a substantial rise in the number of mice.

Mice do not require prompting as they are capable of reproducing at 60 days old. Female mice have the ability to give birth to four or five litters per year, with approximately seven to eight offspring in each litter.

Approximations suggest that the population of mice on Marion Island exceeds one million. These mice primarily consume invertebrates but are increasingly preying on seabirds, including both nesting chicks and adults.

One tiny mouse can consume a bird much larger than itself multiple times. Researchers captured an image of the mouse sitting on the bloody head of a young wandering albatross.

The occurrence of mice consuming seabirds has only been observed on a few islands around the globe.

The occurrence and rate at which mice hunt seabirds on Marion Island has significantly increased, according to Wolfaardt. This trend was first noted in 2003. Wolfaardt explained that the birds have not evolved methods to defend themselves against these unfamiliar predators and often remain still as the mice slowly eat away at them. In some cases, multiple mice may gather to attack a single bird.

According to the remarks made by the conservationists, it is predicted that 19 types of seabirds will go extinct on the island in a span of 50 to 100 years if no measures are taken.

Wolfaardt stated that this island, which is vital for seabirds, is at risk due to the effects of mice.

The removal plan aims for a one-time successful outcome and leaves no margin for mistakes. Increased numbers of mice and rats have posed difficulties for other islands. South Georgia, located in the southern Atlantic, was declared free of rodents in 2018 following a multi-year eradication effort; however, the plan for Marion Island could be the largest single intervention.

“Wolfaardt stated that four to six helicopters will probably be utilized for dispensing approximately 550 tons of rodenticide bait over the island. The pilots will be provided with precise flight paths and Wolfaardt’s team will be able to monitor the drop using GPS mapping.”

The lure has been created with the intention of not disrupting the land or water ecosystems on the island. It will not pose a threat to the seabirds, as they primarily feed in the ocean, and will not cause any harm to the environment, according to Wolfaardt. While certain animals may experience minor effects, they will eventually bounce back.

He stated that there is no ideal answer for these types of issues and there is not a single method that eliminates mice without any other consequences.

BirdLife South Africa and the national Department of Forestry, Fisheries, and the Environment have joined forces to implement the eradication project on Marion Island. The island has been officially designated as a special nature reserve with the utmost protection. While it does have a weather and research station, it is otherwise unpopulated and solely devoted to conservation efforts.

The department emphasized the importance of getting rid of mice in order to protect the island’s unique biodiversity.

Wolfaardt stated that due to the level of preparation required, it is expected that the project will commence in 2027. Additionally, the project requires a total of $25 million in funding, a portion of which has been provided by the South African government. The project also needs to obtain final regulatory approvals from relevant authorities.

Previously, researchers have attempted to manage the population of mice in Marion.

They were already a pest for researchers in the 1940s, so five domestic cats were introduced. By the 1970s, there were around 2,000 feral cats on the island, killing half a million seabirds per year. The cats were eliminated by introducing a feline flu virus and hunting down any survivors.

Islands are critical to conservation efforts, but fragile. The Island Conservation organization says they are “extinction epicenters” and 75% of all species that have gone extinct lived on islands. About 95% of those were bird species.

According to Wolfaardt, this project is a genuine effort to restore the environment. It presents a unique chance to address a long-standing conservation concern once and for all.

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Source: wral.com