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Protecting Paradise: A Small Island of 350 Residents Successfully Decimated 300,000 Rats

Mona is a veteran writer, educator, and coach. She enjoys researching historical personalities and investigating the past.


“Conservation can be as much a social science as an ecological science.” ~Michael Slezak, The Guardian

“If humanity can find better solutions, nature will often come in and fill the rest.” ~ Kris Helgen, chief scientist, Australian Museum

Lord Howe Island (LHI) is, only 11km long and 2km wide. This island on the Tasman Sea is part of Australia, and 350 residents occupy only ⅓ of it. The rest of the island is a Nature Preserve Park for endangered flora and fauna.

For the locals, it’s Paradise with 15 beaches, white sands, and crystal clear waters. This UNESCO World Heritage site has 90 different coral species, 500 fish species, and hundreds of plant and animal species that don’t exist anywhere else in the world.


Islanders with attitude

Many of the 350 residents of LHI are descendants of the first LHI settlers who came in 1788 when the island was unpeopled. Many islanders occupy the same land as their ancestors did 160 years back. Residents proudly tell tourists they’re fifth, sixth, or seventh-generation islanders.

Tourists get the rare experience of the islander lifestyle first-hand. Only a maximum of 400 people can be residents, and only 400 visitors can be on the island at one time to preserve LHI’s ecosystem and way of life.

Lord Howe Island completely eradicated its invading rat and mouse populations. The island's ecology recovered almost immediately.

Lord Howe Island completely eradicated its invading rat and mouse populations. The island's ecology recovered almost immediately.

Enter the rats

House Mice (Mus musculus) first appeared on LHI in 1850. But on June 15, 1918, black rats (Rattus rattus) swam to LHI when the British steamship S.S. Makambo ran aground near the island’s shores.

The extremely aggressive black rats ate animals, bird eggs, chicks, fruits, food scraps, grains, human waste, insects, nuts, and vegetables. They like living among humans in and around buildings, because food, water, and shelter are easily found. This makes humans vulnerable to rat-transmitted diseases.

They can reach inaccessible places by climbing, jumping, burrowing, or gnawing their way through. They've few natural predators, and reproduce rapidly, averaging 150 offspring annually per female rat.

Though endemic to India, black rats now prevail worldwide. In the wild, they live in forests and lush subtropical boscage. In both the wild and in home gardens, they nest in cavities on tree tops, if the tree provides food.

The rats on LHI ruined grain supplies, crops, seeds, plants, and gardens; and rendered five endemic bird species, 13 endemic invertebrate species, and two plant species extinct.

They also preyed upon two reptile species, 51 plant species, 12 vegetation communities, 13 other bird species, and seven threatened invertebrate species.


Finding black rats

At their apex, the rats numbered some 300,000, at a ratio of 1,000 rats to one human. Rats were seen climbing up and down trees but despite their huge number, they were very hard to find.

Instead people saw their mess such as devastated vegetable gardens, and scattered seeds that were dispersed through their dung. Native birds disappeared, as did crickets. By day the rats slept soundly in their underground homes. But sometimes their paw prints were seen in the sand.


Rat extermination plan (REP) – disputes among islanders

To control rat populations, the Lord Howe Island Group (LHIG) distributed five tons of rat bait to residents, but this failed to hold their numbers down. A clear, comprehensive eradication plan was badly needed.

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In 2001 the LHI Board received a feasibility study designed to eradicate rats and mice. It included reviews of over 300 successful rat eradication programs conducted on other islands.

However, the difference between those REP programs and LHI was that the former islands were either unoccupied or privately owned. LHI would be the first island to implement REP among its permanent residents.

By 2009, the plan included dropping 42 tons of poisoned cereal on the island. This split the community down the middle.


Culture war

The reaction of the local community was a forceful obstacle. Those who made the plan didn’t factor Islander culture in. LHI residents live like a small country town on a remote island. They nurture robust disrespect for mainland authority.

When the islanders were first told of REP, controversy arose, splitting its 350 residents. Families were divided, and neighborhoods became undone.

In one case, a fight occurred at the Lord Howe Island Golf Club between those who were for REP versus those who were against it. In another instance, two islanders fought violently, and a local tour guide faced assault charges in the aftermath.

Public officials didn’t understand the sentiments of the island community, whose families lived there for up to seven generations maximum. It took 20 years before LHI’s divided populace ended the issue with a plebiscite in 2015. The results showed 52% in favor of REP.

Mount Lidgbird and Mount Gower viewed from Mount Eliza, photographed by Fanny Schertzer.

Mount Lidgbird and Mount Gower viewed from Mount Eliza, photographed by Fanny Schertzer.

The concerns of anti-REP islanders were:

  • Resentment that mainlanders were doing things to their island.
  • Suspicion and distrust because the project idea came from public officials and New Zealanders, rather than from islanders.
  • Failure of the plan to incorporate the psychology of the islanders.
  • The belief that REP's response to rats is overdone.
  • Fear that the ecosystem would be further compromised by REP.
  • Fear of unintended consequences due to REP.
  • Concern for local birds and marine life.
  • Possible risks to human health.
  • Tourism would be affected.
  • REP might not work.

In sum, the division among dwellers portrayed how conservation is more than an ecological science. Sometimes, it requires social science as well.

Little island on Mt Lidgbird track Lord Howe Island, photo by Granitethighs,

Little island on Mt Lidgbird track Lord Howe Island, photo by Granitethighs,

Precautions are taken by REP

The LHI Board said the program was rigorously assessed to ensure minimized impact on people and domestic and native animals, even as they used the strategies and utilities to ensure the total eradication of rodents.

Because the endangered woodhens and currawongs were at risk, Sydney’s Taronga zoo gathered these and brought them to the Zoo, where they stayed while REP was in progress.

Beef cattle were slaughtered two years before REP. The owners were either paid for the cattle’s value or promised replacement cattle after the baiting is complete.

Dairy herds remained on LHI throughout REP but were confined to a small paddock that was linked to the milking shed. Confinement continued until baits disintegrated. Also, aerial baiting was disallowed within 30 m of the paddocks. In the 30 m buffer zone, baiting was done manually, and baits in the holding paddock were cattle-proof. The same arrangement was made for goats and horses.

All livestock were fed freshly cut grass from empty paddocks to avoid food storage that the rodents might access for food instead of the baiting stations.

Lord Howe Island Rodent Eradication Project (Short)

Residents were also warned not to eat local eggs, milk, or fish livers until they are confirmed free of any trace of poison. They were also given Vitamin K1, which is an antidote for rat poison.

LHI receives some 16,000 tourists annually. They were advised against eating fish after the airdrop of poisonous pellets to avoid the risk of food chain contamination.

Walking in the forest was disallowed, and residents were advised to cover their roofs with tarps so that their water tanks won’t be affected by the bait poisoning.


Implementing REP

The LHI program, the result of 15 years of research and careful planning, included risks that the study said were manageable and controllable.

The Rat Extermination Plan (REP) was scheduled to be implemented from May to November 2019. For optimal, long-term results, they decided to eradicate both rats and mice.


Timeline 2019 rat extermination plan (REP)

When REP was implemented in 2019 the following was done:

  1. The plan’s full implementation occurred in 2019 after risks were fully investigated and addressed.
  2. Baiting was installed on private property, whether homeowners wanted it or not.
  3. Pellets were scattered by hand in areas where residents knew the rats liked to frequent.
  4. Some 22,000 lockable traps were scattered in residential areas filled with poison-laced grain pellets that were placed around the island in 2,499 areas, each set 10 meters apart.
  5. Traps were also distributed through human-occupied areas and along waterways.
  6. Bait trays were set up in homes, particularly in spaces between the ceiling and the roof, and crawl spaces under the floor, where rats like to nest.
  7. Bait stations were placed in paddocks that were used for dairy herds, cattle, horses, and other livestock.
  8. Baits were scattered via helicopter using bait spreader buckets in unreachable areas. The bait stations were regularly dropped in these areas for two months, totaling 42 tons of poisoned cereal dropped by helicopter.
  9. Every few months, rat detection dogs would visit LHI to ensure that the black rats were truly gone and to make sure they hadn’t come back.
  10. Cruise ships are banned.
  11. The last black rat seen was spotted and killed by a detection dog in August 2021.

Paradise Recovered

By Feb. 2021, just 15 months after the implementation of REP, wildlife began to recover at an unexpected rate.

  1. Never-before-seen fruits are now growing, including fruits from vines that islanders thought were unproductive.
  2. Flowers are blooming from native plants.
  3. Hundreds of insects have returned, and some of them were never seen before.
  4. New seedlings are covering the soil. Many of them have never been seen before.
  5. The flightless woodhens were returned to LHI and their population doubled to 565 in three years.
  6. Other endangered species’ numbers have also risen including the black-winged petrel and endemic land snails.
  7. Crickets are chirping again.
  8. Four land snail species were so critically endangered that before REP, only their empty shells were seen on the island. Now, they are thriving. One snail, the Gudeconcha sophiae magnificaen, was the first live animal that was seen in LHI in 20 years.

The REP was so successful that it received a Froggatt Award in the category, Control and Eradication. As of now, it’s a matter of making certain that the rats don’t come back or repopulate. Regular surveillance will be needed to ensure this. Meanwhile, it’s nice to know that a slice of paradise on our good earth has come back so richly.

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