THE LAST CATS on Ascension Island in the south Atlantic held out in the volcanic rocks around Cricket Valley, on the eastern tip of the island. They were all female: according to Mike Bell of Wildlife Management International, a New Zealand company, who was in charge of eradicating the island’s 500 or so feral cats, females tend to be shy and wary of potential traps. Mr Bell and his colleagues tried everything: fish, cat biscuits, day-old chicks, traps of all shapes and sizes. Eventually, on January 30th 2006, about six months after they had expected to finish the job, they trapped the last one—“a scruffy tabby, quite small”—and for the first time in 200 years the islands were safe for birds.

In 1815, when the island was first garrisoned by the British, around 20m birds are thought to have been living on it. By 2000, thanks largely to the offspring of ships’ cats, the numbers were down to a few hundred thousand. The rocks were covered with ghost seabird colonies—miles of stony ledges covered in guano deposited over millennia, with hardly a bird to be seen. The Ascension frigate bird, endemic to the island, had been driven to nesting on an offshore rock the cats could not get to.

Most eradications of undesirable species have been carried out on unpopulated islands, but Ascension has people—soldiers and spies, mostly, manning the British military base and listening post. Many of them had adopted cats from the feral population. Around a third of the tame cats died, which caused some contretemps between locals and eradicators.

The eradication programme may not have worked out for some of the cat owners—though since the human population is transient, the bereaved may have found feline love elsewhere—but the bird population is rebounding, and last year the Ascension frigate bird nested on the island itself for the first time in 150 years. Credit goes to the RSPB, which organised the eradication programme, and the British government, which paid for it.

Programmes to get rid of invasive species are one way in which governments, with varying degrees of enthusiasm and effectiveness, try to tackle threats to other species. Others are laws against killing endangered creatures or trading in them, regulations to make pesticides safer and protection of habitat.

Nobody much cared about the killing of wildlife until well into the 20th century. The American bald eagle, for instance, was routinely slaughtered throughout the 19th and the early part of the 20th century because it was believed to prey on lambs and even children. Benjamin Franklin opposed its selection as a national emblem, arguing that the eagle “is a bird of bad moral character.” Numbers dropped from up to half a million in the 18th century to 412 breeding pairs in the early 1960s. Now that killing them has been outlawed, there are reckoned to be 7,066 breeding pairs.

Crying wolf

As the environmental movement took off in the 1960s, wider laws followed, mostly in the 1970s and 1980s. America’s Endangered Species Act was signed into law in 1973 by Richard Nixon. Europe’s Berne Convention, ratified as national law among its signatories, came into effect in 1982. The bans on killing were of particular benefit to predators which people regarded as a threat to their lives or livelihoods. Wolves, lynx and wolverine all nearly got wiped out in western Europe and are all doing pretty well these days—too well, in the eyes of many farmers and hunters. In the Great Lakes and the north-west of America, the wolf population has recovered so strongly that it has become a big political issue.

Whales are generally thought to be recovering, too, thanks to whaling bans. The humpback, which has been protected longer than other species, is known to be flourishing. Whaling still goes on—some countries ignore the ban, and Japan gets special licences for “scientific” whaling—but there is far less of it.

Trade in endangered species has been limited through the Convention on International Trade in Endangered Species (CITES), which came into force in 1975 and covers about 34,000 species, the best-known being elephant and rhino. It worked pretty well for them to start with, but rocketing demand for ivory and rhino horn has proved irresistible (see article).

Pesticide regulation, too, has been tightened over the years, partly thanks to Rachel Carson. She not only exposed the dangers of DDT but also campaigned to create the Environmental Protection Agency (EPA), pointing out that America’s Department of Agriculture, being responsible both for promoting the farmers’ interests and for regulating pesticides, was suffering a conflict of interests. Before the EPA was created in 1970, pesticides had to be registered but were virtually unregulated. Now the EPA requires new pesticides, or pesticides being used in new ways, to undergo around 100 different tests, which takes around two-and-a-half years. Regulation in Europe, partly the responsibility of the European Commission and partly of member states, is tougher still. Getting a pesticide from the lab to the market takes seven or eight years, and pesticides cannot be marketed if they leave residues of more than 0.1 micrograms per litre of water, irrespective of their toxicity. Earlier this year the EU agreed to impose a temporary ban on neonicotinoids, which are thought to be implicated in the decline of bee populations, though they are still being used in America.

Invasive species have been solely responsible for 20% of extinctions since 1600 and partly responsible for half of them. These days huge efforts are made to combat such species, through both prevention and eradication. Most countries have customs regulations to stop them entering in the first place. Over 1,200 eradication programmes have been carried out, mostly on islands, which tend to have a high proportion of vulnerable endemic species and where eradication is relatively easy. Piero Genovesi, chairman of the specialist group on invasive alien species of the International Union for the Conservation of Nature (IUCN), says that 86% have been successful. Not all have had the intended effect: on Macquarie Island, a World Heritage site between New Zealand and the Antarctic, the eradication of cats (introduced in 1820) led to an epidemic of rabbits (introduced in 1878) which devastated the native vegetation. But most have benefited local wildlife, and sometimes the local economy too. For instance, the eradication in the 1980s of coypu in Britain, which had escaped from fur farms, cost around €5m but is reckoned to have saved the country a lot of money. According to Mr Genovesi, Italy, which still has coypu, has spent €11m euros over the past six years on mitigating the damage they do, and the costs look like rising further.

Somewhere to live

The biggest challenge for governments, and the area where most effort and resources have been focused, is habitat loss. The main means of limiting it is to create protected areas such as national parks. Such efforts go back a long way—hundreds of years, if you include monarchs’ reservation of hunting areas such as Bialowiesa Forest in Poland, where King Sigismund I imposed the death penalty for bison poaching in 1538.

Limiting or banning development in areas of great beauty or biological value is a newer idea. America led the way with such efforts, starting with an act dated 1864, signed by Abraham Lincoln, which ceded Yosemite to California, requiring that “the premises shall be held for public use, resort, and recreation; shall be inalienable for all time.” But the first truly national park was Yellowstone, established in 1872. There was opposition from local interests more concerned about development than scenery, but Theodore Roosevelt, a young and eloquent congressman, helped persuade Americans it was a good plan.

Slowly, parks started to spring up around the world—mostly, to start with, in British colonies such as Canada, Australia and New Zealand. Sweden set some up in 1909, but Europe was generally slower to get going than America, possibly because its land was scarcer and its landowners more powerful. Britain got its first parks only after the second world war.

These days more and more land is being protected. A study in 1985 suggested that 3.5% of the planet’s land area was protected at the time; another in 2009, by Clinton Jenkins of the University of Maryland and Lucas Joppa of Duke University, found that the figure had gone up to 13%. The 2010 Aichi meeting of the signatories of the Convention on Biodiversity set a target of 17%, which given the recent progress may even be met.

Protecting land is not always popular. Many parks were established by philanthropists in the face of public opposition. Grand Teton, for instance, was created from land owned by John D. Rockefeller. There was so much opposition to his plan that Franklin Delano Roosevelt used an act which allowed the president to set aside land as a national monument to avoid having to go through Congress. Foreigners have an even harder time of it. Doug Tompkins, founder of Esprit, a fashion retailer, has bought up around 2m acres of Chile and Argentina which he plans to hand over to the state, but locals have been far from enthusiastic about his determination to keep it pristine.

Yet it is not just rich people, or rich countries, that want to protect ecosystems. The biggest increase in protected areas in recent years has been in Brazil. China created its first national park in 1982; it now has 1,865 of them, covering 110m hectares, three times the area of America’s parks (though since the level and nature of protection afforded by national parks differs between countries, they are not strictly comparable). A recent paper by Canadian and Chinese academics attributes this growth to the creation in 1995 of the five-day working week as the norm, and the subsequent introduction of “Golden Week” holidays. Chinese people, like the rest of humanity, want to escape their factories and enjoy nature as they become more prosperous.