Lord Howe Island lies roughly 370 miles (600 kilometers) off the eastern coast of Australia -- a crescent-shaped volcanic remnant in the Tasman Sea. Its dramatic cliffs, lush subtropical forests and pristine coral lagoons are home to a breathtaking array of plants and animals, many of which are found nowhere else on Earth.
Recognized as a UNESCO World Heritage Site, this isolated ecosystem once thrived in an untouched harmony that seemed impervious to the outside world. That was until 1918, when a fateful shipwreck altered the island's ecological balance forever.
Before the grounding of the SS Makambo, Lord Howe Island was even more biologically diverse, with a unique assortment of species coexisting in delicate equilibrium.
Within a decade of the ship's grounding, five bird species, 13 invertebrate species and numerous plants were lost forever, victims of an environmental catastrophe unleashed by one invasive predator -- the black rat.
The SS Makambo, a steamship that traveled between eastern Australia and the islands of the Tasman Sea and Melanesia, met with misfortune on June 14, 1918. On one of its trips near Lord Howe Island, the vessel ran aground near Neds Beach. The damage to the ship would take nine days to repair.
During this time, black rats (Rattus rattus) aboard the ship made their way ashore. For the island, this accidental introduction was catastrophic.
The black rats quickly established themselves in the island's lush environment. With no natural predators and an abundance of food, their population exploded, setting off a chain reaction of ecological destruction.
The rats' arrival marked the beginning of an invasive reign that would devastate Lord Howe Island's vibrant ecosystem.
The immediate impact of the black rats was felt most acutely by the island's bird populations. The rats targeted eggs and chicks, leading to the rapid extinction of several endemic species. Among the losses were:
Adding to this devastation, house mice (Mus musculus) also made their way to the island around the same time, likely aboard ships like the SS Makambo. Though smaller than rats, these mice were equally destructive, competing with native species for resources and preying on invertebrates and seeds.
The island's invertebrates also suffered immensely. The Lord Howe Island stick insect -- once a pervasive fixture on the island -- was declared extinct on the main island by 1920. Thirteen other invertebrate species met the same fate as the rats and mice spread unchecked.
The ecological damage extended to the island's flora. The rats and mice consumed seeds and seedlings, hampering the regeneration of native plant species. This further destabilized the delicate ecosystem, leaving it vulnerable to additional disruptions.
In an effort to control the burgeoning rat population, conservationists introduced Tasmanian masked owls (Tyto novaehollandiae) to Lord Howe Island between 1922 and 1930 as a form of biological control.
However, this solution created a new set of problems. Rather than focusing solely on the rats, the owls preyed heavily on the island's native birds, exacerbating the crisis.
One of the most tragic losses attributed to the owls was the extinction of the Lord Howe boobook owl (Ninox novaeseelandiae albaria). This endemic owl, already struggling due to habitat destruction and competition, fell prey to the larger and more aggressive masked owls.
The masked owls' presence added to the predation pressure on other species, including the Lord Howe woodhen and various seabirds. By introducing yet another non-native predator, the island's ecosystem was further disrupted, compounding the devastation wrought by the rats.
Decades after the Makambo's grounding, the ecological scars of the rat invasion remained on the island. In 2019, following 20 years of planning and debate, the Lord Howe Island Rodent Eradication Project (LHI REP) was launched. This ambitious initiative aimed to remove every rat and mouse from the island.
The project involved a combination of aerial baiting and ground-based bait stations. The bait, a rodenticide laced with grain pellets, was carefully distributed across the island.
In the human-inhabited areas, bait was placed in tamper-proof boxes to minimize risks to non-target species. The campaign also included the removal of the masked owls, which had thrived on the rat population but now posed a threat to native wildlife.
The project was not without controversy. Some residents voiced concerns about potential risks to human health, domestic animals and native species.
Targeted measures were implemented to address these concerns. The bait was placed in tamper-proof stations and vulnerable native birds such as the Lord Howe woodhen and currawong were housed in protective aviaries during the baiting period.
By October 2019, the island was declared free of invasive rodents, marking a monumental success in conservation history.
The aftermath of the eradication project has been a testament to the resilience of Lord Howe Island's ecosystems. Many species, long suppressed by the rats' presence, began to rebound.
The Lord Howe woodhen, once on the brink of extinction, saw its population more than quadruple, increasing from 250 birds to over 1,100 in just four years. The black-winged petrel -- a seabird whose breeding success was once as low as 2.5% -- experienced a dramatic increase to 67% following the removal of the rodents, according to an August 2022 study published in Bird Conservation International.
Rediscoveries added to the sense of hope. The Lord Howe Island wood-feeding cockroach, presumed extinct for over 80 years, was found alive in 2022. Similarly, several snail species thought to be lost were rediscovered, underscoring the transformative impact of removing invasive species.
Plans are now underway to reintroduce the Lord Howe Island stick insect to its native habitat. Captive breeding programs have successfully produced thousands of individuals, setting the stage for a carefully managed reintroduction. With the island's ecosystems on a path to recovery, the once-decimated tree lobsters may soon roam freely again.
The story of the SS Makambo and its aftermath is a cautionary tale about the unintended consequences of human activity. Yet, it also demonstrates the power of perseverance and collaboration in conservation. Protecting this fragile paradise requires vigilance, but the rewards -- a thriving, biodiverse ecosystem -- are well worth the effort.