Easter Island, known as Rapa Nui, stands as one of the most isolated inhabited landmasses globally. Its remote location contributed to a unique geological history, shaped by volcanic origins. This distant setting has long captivated observers.
Easter Island’s Original Animal Life
Before human arrival, Easter Island possessed a limited array of native animal life, primarily due to its extreme isolation. The island was once home to extensive seabird colonies, with fossil evidence suggesting over 30 resident species, including albatrosses, petrels, and boobies. These birds played an integral role in the island’s ecosystem, contributing to nutrient cycling and seed dispersal.
Terrestrial animal life was far less diverse, lacking native mammals, amphibians, or most reptiles. The land-based fauna consisted mainly of invertebrates such as isopods, spiders, insects, worms, a single species of land snail, and a centipede. Archaeological studies identified the remains of at least six species of native land birds, including rails, parrots, an owl, and a heron, all now extinct.
Animals Introduced by Humans
The arrival of Polynesian navigators to Easter Island initiated a profound transformation of its ecosystem through the introduction of new animal species. Early settlers brought the Polynesian rat, or kiore (Rattus exulans), which became a significant factor in the island’s ecological changes. These rats consumed the seeds of native trees, notably the large Easter Island palm, severely hindering forest regeneration.
Polynesians also introduced chickens (Gallus gallus domesticus), which provided a valuable food source and feathers. European contact in the 18th and 19th centuries led to the introduction of larger livestock, including sheep, cattle, and horses, along with other rodent species like the ditch rat (Rattus norvegicus) and the house rat (Rattus rattus). These introduced animals, particularly the grazing livestock, further impacted the island’s vegetation and contributed to habitat degradation.
Current Land Animals
Today, the terrestrial animal population of Easter Island is largely dominated by the descendants of these introduced species. Wild horses, cattle, and sheep roam freely across the island, a visible legacy of past agricultural practices. Domesticated chickens are still prevalent, often seen near homes and archaeological sites.
Various rat species, including the ditch rat, house rat, and the house mouse (Mus musculus), persist across the island, having arrived unintentionally on ships over time. While most native land birds are extinct, two small species of lizards, the white gecko (Lepidodactylus lugubris) and a small lizard (Ablepharus boutoni poecypleurus), represent the only surviving native terrestrial vertebrates. A few microscopic native insect species, such as springtails and isopods, have managed to endure within the island’s volcanic caves.
Marine Animals Surrounding the Island
The waters surrounding Easter Island host a diverse array of marine life, reflecting its isolated position in the Pacific. More than 150 species of fish have been reported in the area, with a notable percentage, approximately 25% to 77%, being endemic, found nowhere else globally. These include various reef fish, tuna, mahi-mahi, and several species of moray eels.
Recent deep-sea expeditions have also uncovered dozens of new marine species, including fish, squid, corals, sea stars, and sponges. Marine mammals are also present, with various whales, such as blue, minke, humpback, and sperm whales, migrating through the area. Dolphins, including bottlenose and common dolphins, are frequently observed in the surrounding ocean. The marine ecosystem also supports a range of invertebrates, including mollusks, crustaceans like the Easter Island spiny lobster, and various types of corals.