The last rat seen on Lord Howe Island was sniffed by a detector dog about 15 months ago, not long after a sometimes controversial program began to rid the island of an estimated 200,000 vermin.
The change on the islet since the rats disappeared has been spectacular, says Terry O’Dwyer, a biologist who worked on the program.
Shoots now cover parts of the island’s forest floor and the famous Kentia palms are full of fruit.
Most significantly, the number of Lord Howe’s flightless Woodhen has risen again, made extinct by the rats that competed with him for food and even hunted his eggs and young.
Fears that the Woodhen might succumb to the bait program implemented between June and July 2019 led some islanders to resist the effort, prompting scientists to capture and hold them while the rats were exterminated.
Lord Howe Woodhen, copyright Rob Morris, of the Surfbirds Galleries
“We knew they would be fine once we released them,” said Dr. O’Dwyer. “They started copulating before they were out of sight.”
In a recent survey, 440 chickens were counted, twice as many as a year earlier.
Wildlife has already caused the extinction of six bird species, including Lord Howe Island Fantail, White Eye, Gerygon, Star and Thrush, as well as 13 invertebrates and two plant species. Since rushing ashore from a shipwreck in 1918, rats have caused or contributed to extinction.
The effects of extinction have baffled some observers.
“It blew my mind,” said tour operator Jack Shick. “I’ve been a huge supporter of [the eradication] but i’m incredulous of what i see There are more birds, there are berries on the trees and insects are coming back. At night we hear crickets again. I remember this sound from my childhood.
“What excites me is that there is no one living on Lord Howe who can tell us what it was like before the rats came, so there is a new discovery around every corner.”
Assessing the effects on larger animals will take longer, but according to Dr. O’Dwyer has increased petrel breeding success rates on the island from 2 or 3 percent to over 70 percent.
Island invasive species eradication programs have become a key tool in combating the global extinction crisis. The island’s invasive species extinction database recorded 2,000 programs between 1950 and 2019.
The $ 15.5 million Lord Howe Island program included intense ground and air bait in 2019, backed by ongoing surveillance and increased quarantine measures.
“This is an exceptional example of community efforts, backed by the world’s leading scientists,” said NSW Environment Secretary Matt Kean, who visited the island last week.
The island is expected to be declared rodent-free later that year, two years after the bait was finished.