Forty semi-automatic rifles. Hundreds of thousands of rounds of ammunition. Seventy hunting dogs. Two helicopters.

Imagine a supply list for conservation fieldwork, and it is unlikely the above items would come to mind. Yet these were among the ingredients of the Isabela Project, an invasive-species eradication campaign on the Galápagos Islands that scientists are calling the world’s largest and most successful such effort ever.

The main goal was to rid Isabela Island, the largest link in Ecuador’s famed Galápagos chain, of a spectacularly destructive population of 120,000 feral goats. Begun in earnest in 2004, the campaign culminated when organizers announced this July that they had eliminated almost all the goats, which originally were deposited on the islands by sailors in the 1800s to serve as a store of food.

For anyone concerned with animal rights, slaughter on this scale might seem egregious. But conservation scientists on the Galápagos argue that the project has been essential in heading off the wholesale destruction of plants and animals on Isabela Island—including local populations of some of the native Galápagos species that inspired Charles Darwin’s theory of natural selection.

They report the project has prompted early-stage recovery of native flora and fauna, and in the process has demonstrated that eradication of invasive species in vulnerable island ecosystems can succeed on a scale never before thought possible.

“Almost nobody thought we could do it,” says Felipe Cruz, who directed the Isabela Project and now is technical director for the Charles Darwin Foundation, a nonprofit that conducts conservation research on the islands. “Now, because of this project, the natural communities on Isabela are making a comeback. The giant tortoises of the Galápagos are being saved. We are sharing the lessons from this project and helping many other islands around the world face down the same problems.”

The Galápagos Islands, an archipelago comprising 13 main islands and an overall land mass of more than 3,000 square miles (7,800 sq. kms), face manifold environmental pressures.

There are the periodic conflicts between Galápagos National Park officials and local fishermen about over-exploitation of marine species. In 2004, artisanal fishermen on the Galápagos stormed the offices of the park and the Charles Darwin Research Station to protest fishing restrictions and later clashed violently with park personnel over leadership of the park. (See “Galápagos furor prompts minister’s resignation”—EcoAméricas, March ’04 and “Galápagos turmoil undermines conservation”—EcoAméricas, Oct. ’04.)

Nor are the islands immune to accidents. In 2001, the cargo ship Jessica ran aground, spilling thousands of tons of oil. (See “Regulators scramble following Jessica spill”—EcoAméricas, Feb. ’01.) And there are other pressures posed by expanding development and tourism. (See “Galápagos feeling population, tourism pressures”—EcoAméricas, May ’06.)

Tourism now accounts for 130,000 visitors a year, double the rate of 10 years ago, the local tourism chamber says. And despite residency restrictions aimed at controlling population growth, the number of year-round residents is growing by about 7% annually as mainland Ecuadorians move to the islands legally and illegally to land tourism-industry jobs.

Scientists say the growing number of visitors and year-round residents only exacerbates the chief environmental threat to the islands—invasive, non-native species ranging from feral pigs and goats to cockroaches and quinine trees. Some of these invaders, such as pigs, donkeys and goats, were brought on purpose by whalers, pirates or settlers. Others, including rats, insects and invasive-plant seeds were—and continue to be—transported unwittingly.

The World Conservation Union (IUCN) defines an invasive species as “an alien species that has become established in natural or semi-natural ecosystems or habitat, is an agent of change and threatens native biological diversity.” Currently, 295 such flora and fauna species on the Galápagos fit that description. In fact, today there are more introduced plant species than endemic species on the islands, and the threats from invasive species are multiplying with the boom in development and tourism over the past decade.

In 1994 and 1998, Ecuador passed laws prohibiting the importation of live animals and plants and set strict limits on immigration, but immigration control is lax and invasive insects and plant seeds are especially hard to track. In 1999, a quarantine and inspection system for the Galápagos was established, and in the first six months, despite its limited capacity initially, it detected 33 different insect species amid shipments of fruits and vegetables.

“Historically, the biggest direct threat to native species on islands everywhere is invasive species,” says Graham Watkins, executive director of the Charles Darwin Foundation. But Watkins adds that eradication is not enough to restore and protect Galápagos species: “If tourism continues to increase, that increases the scale of the local economy, which in turn makes managing ecological problems more difficult. It means a greater probability of invasive species attacks, pollution, accidental oil spills and unsustainable resource extraction.”

It is against this backdrop that Galápagos National Park and the Charles Darwin Foundation, which maintains a research station on the islands, created the Isabela Project.

The project’s primary focus on feral goats was not surprising. Goats have done breathtaking damage on the Galápagos. Forests in some island areas have become near deserts as the goats have scoured the landscape for vegetation, often consuming the same plants that native animal species such as the slow-moving giant tortoise depend upon. They have eliminated some plant species outright, and have prevented re-growth of others by speeding the erosion of soils. Moreover, the goats reproduce at a high rate and adapt easily to the Galápagos’ dry environment.

Locals say Isabela’s population of wild goats was relatively small as recently as 1985, but some 120,000 were ravaging the landscape just 15 years later.

Qualms about shooting the goats, project leader Cruz says, were amply outweighed by the fact that the animals threatened the survival of 65% of native plant and animal species on the island. These included the local population of giant tortoises, which only are found in the Galápagos and the Seychelles Islands northeast of Madagascar and typically have lifespans well in excess of 150 years.

“The goats are a beautiful animal, but they do not belong there,” Cruz says. “The damage they were creating was by far too unacceptable.”

What Cruz and his cohorts did, essentially, was organize for war. With about US$10 million in financing from the United Nations and a host of private donors, Cruz waded through international and Ecuadorian bureaucracy to import 500,000 rounds of ammunition, 40 semi-automatic rifles, a pair of helicopters and an experienced, six-member crew of invasive-animal hunters from New Zealand. He set up a facility housing 70 hunting dogs and organized the training and equipping of up to 100 local residents to hunt down the goats guided by GIS (Geographical Information System) maps and GPS (Global Positioning System) devices.

The project began in 1998 with a long test run on nearby Santiago and Pinta Islands, and after a slow start succeeded in freeing those islands of goats, pigs and other invasive vertebrates. In 2004, the team transferred its operation to the much larger Isabela Island—a rugged, roadless 1,771-square-mile (4,587-sq-km) expanse featuring five of the world’s widest volcanoes. Karl Campbell, the project’s field director says the crew nevertheless made the transition smoothly and averaged 1.4 bullets for every dead goat. “No army would ever dream of being that efficient,” Campbell says.

The first attack on the goats entailed rapid fire from helicopters with sharpshooters wielding .223 caliber semi-automatic rifles, already a common hunting and invasive-species-control tactic in New Zealand and Australia. The team also made use of satellite images and GPS coordinates. And it divided Isabela Island into a grid on which it registered each kill, thereby allowing the hunters on the ground to more easily track the movements of remaining goats.

“We thought these guys were simply dreaming when they told us they wanted to kill all the goats on the island,” says Steve Collins, a New Zealander who piloted one of the helicopters. “Nobody has ever done anything like that before over such a large area. The terrain we had to cover was simply enormous. But when we saw how serious, methodical and organized they were, using GIS maps and GPS, we changed our opinion. In the beginning, we killed something like 600 goats per hour.”

Enter the Judas goats

Once the goat population thinned, the goats became harder to find. They also began associating helicopter noise with danger, quickly running for cover. The project then made extensive and sophisticated use of so-called Judas goats—goats fitted with radio transmitters and turned loose on the island to lead hunters to herds. The method is highly effective, since goats are very active sexually and adept at seeking each other out.

Project personnel sterilized nearly 900 Judas goats and injected them with hormones aimed at boosting their sexual urges, thereby increasingly the likelihood they’d make contact with goats on the island. Experts say that leaving aside its unprecedented scale, the Isabela Project pioneered various improvements on previous invasive-species efforts—the use of hormones in Judas goats among them.

“The Judas goat techniques used in the Isabela Project were a key advancement for the efforts to eradicate goats everywhere,” says Josh Donlan, a Cornell University ecologist and science advisor to the Santa Cruz, California-based environmental group Island Conservation.

Donlan adds that the Isabela Project proves that acre for acre and dollar for dollar, invasive species eradication might be the most efficient way to protect many endangered species. “The Isabela Project doubled the amount of invasive species that have ever been eradicated on all the world’s islands,” he says. “It’s changed the way we all look at this issue.”

In 1971, after goats were eliminated from Santa Fe Island in the Galápagos, the ecosystem there began to recover, says Ole Hamann, a Danish botanist who has studied Galápagos plants for over 35 years. But Hamann warns that “expectations are not always what happens.” While a small threatened tree called the Scalesia [Scalesia helleri] rebounded nicely on Santa Fe, the Opuntia tree [Opuntia echios], once abundant on the island, recovered more slowly and then suffered a setback as a result of the El Niño weather pattern in 1982-83.

Isabela recovering

The risk of such reversals notwithstanding, the restoration of Isabela Island appears to be underway. With the elimination of nearly all the goats—scientists estimate that some 50 holdouts remain on the southern portion of the island—the native vegetation is swiftly reestablishing itself. The Charles Darwin Foundation, which has long monitored the island, says threatened plants are now popping up all over.

“The vegetation is being restored,” says entomologist Charlotte Causton, science director for the Charles Darwin Foundation. “On one of the volcanoes, Alcedo Volcano, threatened plant species are appearing in places that before had been decimated by the goats.”

Causton says work is now being done to turn back highly damaging invasive plant and insect species. “Invasive species are the principal threat to conservation in the Galápagos,” says Causton. “The impact of invasive species on islands such as the Galápagos is more concentrated as [the] species there are more susceptible because they have never been exposed to predators or parasites.”

Like other experts, she believes eradication is only part of the answer. Says Causton: “For me, prevention is the key. We need to stop more of them from coming while we go after the goats and other high-priority invasive species such as rats, cats, and various introduced plants and insects.”