Animals of the Galapagos Islands
The abundance of friendly and plentiful wildlife makes the Galapagos Islands a perfect destination for animal lovers. One of the greatest aspects of the trip to the islands, from a visitor’s point of view, is the fact that the animals living there are extremely tolerant of our presence; in fact, they have no natural fear of humans and allow us to approach them at close range.
THE ARRIVAL OF NATIVE SPECIES
Scientists agree that the Galapagos Islands were never connected to the mainland. Thus, the ancestors of every plant and animal species native to the islands arrived in the archipelago from somewhere else. Despite being separated by hundreds of miles from the mainland, most of the animals in the Galapagos originated from North, Central and South America and the Caribbean. Land birds and California sea lions arrived from North America, pink flamingos and Darwin’s finches from the Caribbean. Land iguanas, giant tortoises, pelicans, cormorants and boobies all arrived from South America. Fur sea lions and penguins came north thousands of years ago as a result of the Humboldt Current from the Antarctic. Animals that were not so adaptive to the ocean, such as land mammals, had to wait until passage was provided by human vessels.
Today, most scientists accept the theory of long-distance dispersal for bringing life to the Galapagos Islands. It is hard to imagine that so many organisms could endure the hazardous voyage, survive in an unfamiliar environment and reproduce. Flotation rafts of natural vegetation, wind and air currents and oceanic drift all contributed to this “sweepstakes dispersal.” Birds displaced from their migratory routes also landed on the islands. Sea birds carried seeds and invertebrates on their feathers and in their digestive tracts. When they deposited this “cargo,” new colonies took root.
Many animals are not found in the Galapagos. Amphibians and other aquatic animals, for example, are poorly represented. Large terrestrial mammals similarly failed to make the crossing. The lack of herbivorous mammals left a niche open for tortoises. These huge reptiles developed and became the large grazing herbivores on land, a position they enjoyed until the relatively recent arrival of humans with domestic livestock.
Introduced species are the most serious threat to native plants and animals and threaten the fragile ecosystems in the Galapagos. In the 1600s, humans began visiting the islands and brought with them plants and animals that otherwise would not have arrived. Black rats and house mice came as stowaways on ships. In the 1800s, settlers brought domestic animals such as horses, cattle, donkeys, goats, pigs, dogs and cats that escaped or were abandoned. Today, only two out of 14 major islands remain untouched by introduced mammals, and new introductions still occur.
Subsequently, feral populations formed and are today found throughout the islands. The native plants and animals did not have time to develop a defense against the new predators, and the impact has been devastating. On Santiago Island, wild pigs snatch the eggs of sea turtles; on Santa Cruz, wild dogs attack large colonies of land iguanas; on the island of Pinzon, rats have killed every giant tortoise hatchling, leaving only an ever-aging adult population of the resident subspecies. Goats wipe out huge stands of native plants, reducing the vegetation to lifeless shrubs. This not only causes extinction of the plant species and soil erosion, but native wildlife are also robbed of food. The goats’ rapid reproduction rate magnifies the problem.
The balance of life for native species is a concern for all who visit and care about the Galapagos Islands. Through conservation efforts and responsible tourism, the native fauna of the Galapagos will continue to flourish and thrive as it has for thousands of years.
Mammals of the Galapagos