Holly Jones is a conservation biologist who has spent many years working in a variety of environments studying wildlife. But for her, the best of these occurred on Stephens Island in New Zealand. Stephens Island is the site of one the most well-known occurrences of humanity’s tendency to introduce foreign species into the islands. In 1894, a small crew arrived on the island with the intention of creating lighthouses. They brought with them a cat (possibly more than one). But this particular cat kept bringing back in his mouth a small, flightless bird to the lighthouse. It was the Stephens Island wren. But within just a couple years, the entire species had been killed by cats. A few years later, in 1897, the lighthouse keepers decided that something needed to be done to preserve other species from these predators who had been brought in. It took over 27 years to accomplish but from this, standard conservation practices were developed that would be used around the world to protect species that are indigenous to islands
Jones teaches at Northern Illinois University and she is the lead author for a study that is researching the long-term effects of eliminating invasive species from the islands. She is focusing on cats, rats, goats, and pigs. The study is being published in Proceedings of the National Academy of Sciences. She and her fellow biologists have studied results on 181 different islands, including Stephens Island, and their findings have supported the fact that eliminating the invasive species is one of the most effective ways of protecting threatened indigenous species.
While this may seem rather violent and what some may call unethical, the truth of the matter is that conservationists need to do what is best to protect limited species. Currently, the world spends about $22 billion per year on conservation. But less than 1% of that is spent on the islands, which are home to species that can only be found on these certain islands. They also are home to at least 15% of all the land based species in the world and 37% of all of the critically endangered species recorded! Conservationists firmly believe that what they are doing is the most effective way of preserving these exceptional species.
One success story has been the island of Anacapa, which is located in the Channel Islands off southern California. The island was suffering from an invasion of black rats. Animal rights activists urged that the rats be relocated rather than exterminated, even though they were far from being endangered. The protestors failed to realize that while they thought they were protecting the rat species, they were subsequently sentencing the Scripp’s murrelet, an endangered bird species, to extinction.
The extermination of the rats cost $1.8 million, which is more excessive than usual. Researchers had discovered that the poison being used to kill the rats was also effective against a deer mouse only located on the island, so they were forced to round up the deer mice, separate them and place them on a separate island in captivity whilst exterminating the rats. After extermination was completed, the deer mice were reintroduced into their natural habitat. But the results of the extermination were evident almost immediately. Nick D. Holmes, who coauthored the study on the Scripp’s murrelet, said that the researchers on his team saw eggs hatching and the young birds surviving, since they were no longer being eaten in the nest by the rats. Since the extermination completion, the population has more than tripled in size and the icing of the proverbial cake is that researchers have also discovered another species of bird living on the island whose population had also been heavily affected by the rats.
The island restoration projects have already been influential in the conservation of 236 different species, with 25% of those having been threatened with extinction. Four species – the island fox, the Seychelles magpie, Cook’s petrel, and the black-vented shearwater – have also been downgraded in protection level from the Red List maintained by the International Union for Conservation of Nature. In New Zealand, a species of petrel who researchers had previously thought had been driven extinct, has since reappeared after over 150 years. The success of the projects is clearly evident.
But what about the negative effects? On occasion, there have been a few temporary population declines of other species who have accidently consumed the poisoned carcasses left behind. But only a four of these population declines have been permanent, at least for now. For example, on Macquarie Island, located off the coast of Australia, the brown skua, a species of seabird, had been feeding off the invasive species of rabbit living there. Alas, when the rabbit species was eradicated, the seabirds were forced to return to their natural food sources, which are less abundant, but nature has been corrected, as it should have been.
There still remain 804 different islands that are eligible for these types of conservation efforts. One of these happens to be the island known as the setting for Daniel Defoe’s novel, Robinson Crusoe. The island chain is known as the Juan Fernández Islands, and they are located off the coast of Chile. “This is an incredible place,” said Holmes, but it also carries its complications, such as social issues working with the current human inhabitants. These islands carry a variety of different species, including the world’s only oceanic hummingbird, seen pictured, that would be positively affected by the eradication of invader species, but as with the other projects, the results, said Holmes, are “reason to celebrate and to be optimistic. It shows that this type of conservation intervention makes a difference, and it illuminates that there is more work to do.”