US Study Looks at How Islands Are Saving Natives

“In 1894, a pregnant house cat escaped from a lighthouse on Stephens Island, in the Marlborough Sounds. She had her kittens in the wild, where they went feral. Within 13 months, a native bird species known as the Stephen Islands wren was nearly extinct,” Sean Greene reports for the Los Angeles Times.

“It’s a story often cited as an extreme – and by some accounts exaggerated – example of the damage that invasive mammals can do to delicate island ecosystems.

“But the plot is hardly unusual. On islands where native species evolved with no natural predators, intruders like rodents, feral cats and goats can quickly outcompete or even eat the locals.

“Islands are home to 15 per cent of the world’s terrestrial species, but they represent 61 per cent of recorded extinctions, experts say. Invasive species usually were a factor.

“Now a new [Northern Illinois University] study is making the case for a tried-and-true method of staving off this island extinction ‘crisis’: Get rid of the invasive mammals.

“The study looked back on eradication projects since the 1970s and ‘80s, when some of the first techniques were developed for removing invasive mammals. The study also included a 1925 effort to remove the feral descendants of the Stephens Island lighthouse keeper’s cat, which came too late for the wren but aided the recovery of the fairy prion seabird and a nocturnal reptile called the tuatara.

“The analysis includes the eight countries with the most eradications – New Zealand, Australia, Ecuador, Seychelles, the United States, the United Kingdom, France and Mexico. Cases in these countries represent 82 per cent of all invasive mammal eradications around the world.”

Original article by Sean Greene, Los Angeles Times, March 22, 2016.

Photo by Stephanie Borrelle.