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The rats were relentless, said Hank Bower, who has lived on Lord Howe Island for 15 years. At night, they would run up and down the trees, eat food, destroy gardens, destroy the native environment and push animals to extinction. As if to taunt those on the island, they would also leave paw prints in the sand in the morning.
“We would distribute five tonnes of rat bait to the community every year to keep numbers down and we couldn’t keep them at bay,” Bower, who is also the manager of world heritage and environment with the Lord Howe Island Board said.
The rats had called the World Heritage-listed island their home since about 1918, and an estimated 210,000 plagued the island. House mice are thought to have come to the island as early as 1860 and added to the ecological difficulties. But three years ago, an eradication program was put in place. Now the island’s ecosystem is thriving, with native animals and fruit making a quick return.
“What is unfolding is an ecological renaissance, since the rodents have gone, the catchphrase is: ‘I’ve never seen that before’,” Bower said. “There’s a vine which we didn’t know what the fruit looked like, people are taking photos of insects and sending them to the Australian Museum who are saying we’ve only got three of those on record ever but we are seeing hundreds of them. Everything is blooming, all the plants are flowering and we are seeing a carpet of seedlings.”
Among the animals bouncing back is one of Australia’s rarest birds, the flightless Woodhen, whose population has doubled to 565 in the past three years.
Ongoing monitoring on the island continues, including bringing in rat detection dogs every few months to ensure the unwanted pests stay away. The last rat spotted was in August last year. Eradication programs of invasive species on islands have become a key tool against the global extinction crisis.
The Database of Island Invasive Species Eradications has tracked 2000 programs between 1950 and 2019 and shows that the programs have had an 88 per cent success rate on more than 800 islands. But Lord Howe Island offers the first rodent control program to be conducted on a permanently inhabited island.
Among the newly thriving animals on Lord Howe are four critically endangered land snails, whose empty shells once dotted the island. Teams from the NSW government’s Saving Our Species program and the Australian Museum spent more than 400 painstaking hours looking for the tiny snails at 200 survey sites on the remote island. Part of their discovery included a snail called the Gudeconcha sophiae magnifica which was the first live animal seen in 20 years.
Australian Museum chief scientist Professor Kris Helgen said while it was great to see the snails returning, they were just one part of rebuilding a complex and rich ecosystem.
“How do you bring ecosystem back once it has been ravaged? Part of it is being lucky enough to get to some of the fixes in time,” he said. “Predation is one of the most important ecological interactions in any ecosystems.”
But it was the interaction between invasive predators, such as foxes or cats, that could seriously impact native species. “If a better way was found in Australia [to manage the invasive predators] I am hopeful that some of these animals, many of which we think are extinct, maybe they can still be found in some numbers. I think the problem in this case is that we have let the disturbances last too long. But if humanity can find better solutions, nature will often come in and fill the rest.”
“This is an incredibly optimistic sign for the future of conservation,” Minister for Environment James Griffin said.“This is good news for the Lord Howe Island Woodhen, which was once on the brink of extinction, with the population as low as 22 birds in the 1970s.”
“By controlling pigs, cats, goats, plant disease and rodents, Lord Howe Island’s native fauna and flora has been able to recover, demonstrating that good science and management can turn back the tide of biodiversity decline.”
Department of Planning and Environment senior threatened species officer Craig Stehn said while working on islands had many challenges, they also offered unique opportunities which included rolling out successful eradication programs which would not be as possible on the mainland. He added that islands also offer unique ecosystems, often providing homes to animals that aren’t found anywhere else.
Story Source: https://www.smh.com.au/environment/sustainability/i-ve-never-seen-that-before-lord-how-do-you-get-rid-of-200-000-rats-on-an-island-20220421-p5af7s.html