No species has done more to upset the delicately balanced ecosystem of the Galápagos than humans. In one study of thousands of fossil bones, it was found that nearly every extinction of native species followed the arrival of Tomás de Berlanga, the first recorded visitor, in 1535. From that point onwards, the hunting of tortoises, fish, whales, fur seals and other animals has brought populations to the brink. Although our depredation of native species within the park has ceased, and fishing in the marine reserve is strictly controlled, a concerted conservation effort will always be needed to offset the impact of human colonization.
The introduction of foreign species
By far the worst human legacy on the islands has been the catastrophic introduction of alien species. When settlers arrived they brought with them plants, and domestic and farm animals that soon went wild, overrunning the islands and out-competing native species. Pigs trample vegetation, snaffle up land bird hatchlings and young tortoises and devour turtle eggs. Packs of feral dogs have attacked land iguanas, killing hundreds at a time on Santa Cruz and Isabela, and black rats, thought to be responsible for the extinction of endemic rice rats on four islands, killed every tortoise hatchling on Pinzón for most of the twentieth century. Wild goats are regarded as the biggest threat, denuding entire islands of vegetation, causing plant species to become extinct as well as depriving native species, particularly tortoises, of food, and encouraging soil erosion. Among some 490 accidentally introduced insect species are about 55 highly invasive types; these include two species of wasp, which eat indigenous butterfly and moth larvae, and the fire ant, only 2mm long and easy to transport unwittingly to new islands, which is having a devastating effect on native insects as well as attacking hatchling and adult tortoises. Introduced plants are also a major threat, disrupting the food chain from the bottom up. About ninety percent were introduced through agriculture, including guava, blackberry, red quinine and elephant grass, which are out of control on several islands, squeezing out native plants such as tree ferns, scalesia, guayabillo, cat’s claw and others; sixty percent of native plants are thought to be under threat.
The Galápagos National Park Service (GNPS) and the CDF have been following a three-pronged approach to the problem of introduced species. Eradication programmes have done enough to allow some threatened native species to recover. Feral pigs, donkeys and goats have been eliminated from Santiago, and goats have been eliminated from six of the islands and islets. On Isabela, trained dogs kitted with leather boots to protect their paws from the lava surface are being used to track goats down; captured goats – the so-called “Judas goats” – are radio-collared and released, eventually leading hunters back to the herd. The second vital strand of the conservation effort are repopulation programmes, such as the one for giant tortoises, where eggs are gathered, incubated, hatched and raised until large enough to survive predatory attacks before being repatriated. Land iguanas and rice rats have undergone the same treatment, with positive results. A quarantine system in ports and airports has inspectors checking incoming cargoes for alien pests and seeds and the usual stowaway frogs, rats and insects.
Friends of Galápagos
The best thing you can do as a visitor to help the conservation effort is to join the Friends of Galápagos, a network of international conservation organizations. Membership entitles you to detailed news bulletins about the islands and ongoing conservation work, and information on events and appeals. The Friends provide vital funding for the CDRS and the GNPS, both at the heart of Galápagos conservation. In the UK, contact the Galápagos Conservation Trust (GCT), 5 Derby St, London W1J 7AB (t020/7629 5049, galapagosconservation.org.uk); in the US, contact the Galápagos Conservancy, 11150 Fairfax Blvd, Suite 408, Fairfax, VA 22030 (t703/383-0077, www.galapagos.org); check the GCT website for other national Friends organizations or join up in the islands at the CDRS.