Massive Rodent Eradication Planned for Marion Island

Hundreds of tons of rodent poison and helicopters are to be used in a mass eradication planned by conservationists.

TFD – Delve into the critical initiative to eliminate rodents from Marion Island, securing its unique biodiversity and protecting seabirds from extinction.

SACRAMENTO, PORTUGAL— Due to climate change, mice that were unintentionally brought to a secluded island close to Antarctica 200 years ago are proliferating out of control, devouring seabirds, and wreaking havoc in a protected wildlife reserve with “unique biodiversity.”

In order to ensure success, conservationists are now organizing a mass eradication utilizing helicopters and hundreds of tons of rodent poison, which must be dumped over the entire 115 square miles (297 square kilometers) of Marion Island.

Given their propensity for prolific breeding, it might have been all in vain if even one pregnant mouse makes it through.

The ecosystem of the uninhabited South African territory and the larger Southern Ocean is said to be critically dependent on the Mouse-Free Marion initiative, which involves extensive pest management. If successful, it would be the biggest eradication of its kind.

In addition to supporting approximately thirty bird species with internationally significant populations, the island provides a unique, undisturbed habitat for wandering albatrosses, which can reach a height of ten feet, among many other species.

At least until stowaway house mice from seal hunting ships showed up on the island in the early 1800s, bringing with them the first animal predators.

According to Dr. Anton Wolfaardt, the project manager for Mouse-Free Marion, the harm caused by mice has increased significantly throughout the last few decades. He claimed that the primary cause of their dramatic growth in population is the warming effects of climate change, which have transformed the previously chilly and windswept island into a warmer, dryer, and friendlier place.

They are arguably among the world’s most prosperous animals. They have to go in a lot of different places, said Wolfaardt. However, “their breeding season has been extended, and this has resulted in a massive increase in the densities of mice” on Marion Island at the moment.

Mice don’t require motivation. Females can give birth to four or five litters a year, each containing seven or eight infants, starting at around 60 days of age.

Marion Island is home to an estimated one million or more mice. Invertebrates and seabirds, both adults and chicks in their nests, are becoming their main sources of food.

The Port Edwards Islands, a South African colony in the southern Indian Ocean close to Antarctica, include Marion Island, where sooty albatrosses may be seen in this undated photo. (AP via Stefan Schoombie)

A solitary rodent will consume an avian many times its own mass. One was photographed by conservationists perched on the bleeding head of a straying albatross chick.

There are only a few islands in the globe where mice have been observed to consume seabirds.

Since the initial reports of mice preying on seabirds in 2003, Wolfaardt remarked, the number and frequency of mice preying on seabirds on Marion has increased drastically. He claimed that because the birds lack the defense mechanisms to fend off these strange predators, they frequently just sit there while the mice pick at them. Occasionally, a swarm of mice will surround a bird.

According to conservationists, the island will lose 19 species of seabirds within the next 50 to 100 years if nothing is done.

According to Wolfaardt, “the impacts of mice pose a very tenuous future for this incredibly important island as a haven for seabirds.”

There is not the slightest margin for error in the eradication project—it is a one-shot endeavor. Rat and mouse populations that are on the rise have caused issues for other islands. After an eradication effort spanning several years, South Georgia, located in the southern Atlantic, was deemed rodent-free in 2018. However, the Marion intervention may be the largest one-time effort.

According to Wolfaardt, up to 550 tons of rodenticide bait will probably be dropped around the island using four to six helicopters. Wolfaardt’s crew will be able to track the drop using GPS mapping, and pilots will be provided with precise flight paths.

The bait is made such that it won’t harm the island’s water supplies or soil. According to Wolfaardt, it won’t have an adverse effect on the ecosystem or affect seabirds, which feed at sea. Individual animals will be impacted, but the species in question will eventually recover.

“In situations like these, there is never a perfect answer,” he remarked. “Nothing exists that zaps mice in isolation.”

The national Department of Forestry, Fisheries, and the Environment, which designated Marion Island as a unique nature reserve with the highest level of environmental protection, is collaborating with BirdLife South Africa on the eradication project. It is devoted to conservation and is empty save for a weather station and research facility.

According to the department, eliminating mice was “essential if the island’s unique biodiversity is to be preserved.”

Wolfaardt stated that a go-ahead date in 2027 is likely due to the quantity of planning required. In addition, the initiative needs to secure final regulatory permissions from authorities and raise about $25 million, part of which has already been funded by the South African government.

In the past, scientists have attempted to manipulate Marion’s mice.

Five domestic cats were introduced in the 1940s since they were already a nuisance to researchers. There were about 2,000 wild cats on the island by the 1970s, and they killed half a million seabirds annually. By spreading a feline flu virus and tracking down any survivors, the cats were eradicated.

Islands are delicate but essential to conservation efforts. According to the Island Conservation organization, islands are “extinction epicenters,” with 75% of all extinct species having lived there. Approximately 95% of those species were avian.

According to Wolfaardt, “this is genuinely an ecological restoration project.” “It’s one of those exceptional conservation opportunities where you completely eliminate a threat to conservation.”