In November 2022, a diligent campground host on North West Island — a remote coral cay in Queensland's Capricornia Cays National Park, 75 kilometres north-east of Gladstone — noticed something that shouldn't have been there. Black rats.
The island sits in the heart of the **Great Barrier Reef World Heritage Area** and is one of the most significant seabird and turtle rookeries in the region. Black rats don't belong there. And what followed was a race to get them out before they could do what rats on islands always do: devastate the species that evolved without mammalian predators, that lay their eggs in the open ground, that raise their chicks without fear — and suddenly find themselves completely defenceless.
**Why Rats on Islands Are an Ecological Emergency**
The threat posed by black rats to island ecosystems is difficult to overstate. They are omnivores that will eat seabird eggs, chicks, and even adult birds. They dig up and consume turtle eggs. They destroy vegetation. And their capacity to multiply is astonishing: a single breeding pair can produce a population in the thousands within a single year on an island with abundant food and no natural predators.
On North West Island, the stakes were high. The island hosts breeding populations of several threatened and migratory seabird species, as well as a significant sea turtle rookery. The loss of even one breeding season's eggs and chicks to an unchecked rat population could have measurable long-term consequences.
"The November 2022 confirmation that black rats had spread around the island was disappointing, because mice were declared as eradicated from the island just three months earlier," said Senior Ranger **Damon Shearer** of Queensland Parks and Wildlife Service (QPWS). The mice had been dealt with — and then the rats arrived, almost certainly as stowaways on boats or in camping equipment brought by visitors.
**An 18-Month Battle**
The eradication programme was led by the **Queensland Parks and Wildlife Service (QPWS)** in partnership with the **Gidarjil Land and Sea Rangers**, the Traditional Custodians of the area. It combined multiple tactics:
- **Aerial bait drops by helicopter** — the most effective method for covering the island's full extent - **Ground-based bait stations** — carefully positioned to minimise risk to non-target species including the very seabirds and turtles they were trying to protect - **Live trapping** — to monitor population response and reduce risk to wildlife - **Continuous adaptation** — the team regularly altered tactics in response to how the rats were responding to the programme
After the active eradication phase ended, the team then undertook **twelve months of intensive monitoring** using remote cameras and Black Trakka ink traps — pressure-sensitive pads that record the footprints of any small animal that crosses them. Twelve months of monitoring. Zero evidence of black rats.
**Declared Rat-Free**
On **9 March 2026**, the Queensland Department of Environment, Tourism, Science and Innovation officially declared North West Island **rat-free**.
It is a victory that matters far beyond this one island. The Great Barrier Reef's coral cays and islands support some of Australia's most vulnerable seabird colonies — wedge-tailed shearwaters, common noddies, roseate terns — and several species of sea turtle use them as nesting beaches. Each island cleared of invasive predators is a refuge secured, a breeding season guaranteed, a population given a better chance.
**The Visitors' Responsibility**
Senior Ranger Shearer had a clear message as school holidays approach: "As the school holidays approach, we're asking visitors to North West Island to check all equipment for rats and mice before departure and to arrive at the island pest-free."
The rats most likely arrived in a camping bag or boat cargo. They spread across an entire island in months. Eighteen months of intensive, funded, skilled conservation work was required to remove them. The maths is not complicated. Prevention is a check of your bag before boarding.
One island, cleared. The reef's turtles and seabirds have their nursery back. 🌊🐢
*Sources: Queensland Department of Environment, Tourism, Science and Innovation (detsi.qld.gov.au) · Queensland Parks and Wildlife Service · Reef Joint Field Management Program · Reef Trust · March 9, 2026*
