More than 1,400 land iguanas, absent from the island since 1835, have been reintroduced to Santiago Island as part of an ecological restoration programme.
How iguanas ended up on the Galápagos Islands — volcanic islands of recent formation — remains a mystery. The most widely accepted hypothesis is that they arrived by chance, coming from the South American coasts on natural rafts made of logs or clumps of vegetation. After drifting for weeks at the mercy of ocean currents, these ancient and resilient reptiles are thought to have landed on the Ecuadorian archipelago, beginning a gradual process of adaptation that led them to diversify into four species, three terrestrial and one marine. Among these is the Galápagos land iguana (Conolophus subcristatus), classified as "vulnerable" on the Red List of the IUCN, which has suffered a sharp decline over the past 150 years, above all due to the presence of animals introduced by humans, and is extinct on Santiago Island. Or rather, it was extinct — because now, thanks to a reintroduction project, the species has returned to populate one of the archipelago's main islands after almost two hundred years.
The last person to have officially recorded the presence of a Galápagos land iguana on Santiago Island was none other than Charles Darwin in 1835. Between 3 and 4 January, 1,436 iguanas were reintroduced to the island, as announced by Jorge Carrión Tacuri, director of the Galápagos Islands national park. The animals were taken from the nearby island of North Seymour and released in the coastal areas of Puerto Nuevo and Bucanero, since, as park officials explained, these areas have similar ecosystems.
The iguanas were released as part of an ecological restoration and rewilding project for Santiago Island. These large and peaceful reptiles had become locally extinct due to the introduction of domestic or non-native animals such as cats, dogs, pigs and rats. These animals, through competition for resources and predation of eggs and young, caused the rapid collapse of the land iguana population. One of the main threats was the feral pig, which no longer poses a danger to the iguanas, however, having been definitively eradicated in 2001. "The land iguana is an herbivore that helps ecosystems by dispersing seeds and maintaining open spaces free of vegetation," explained Danny Rueda, head of Galápagos protected areas.
The reintroduction project, described by the director of the Galápagos national park as "a great piece of news for the Galápagos, for Ecuador and for the world," was carried out in collaboration with Massey University in New Zealand. One of the programme's objectives is also to protect the iguana population living on North Seymour Island, which numbers around 5,000 individuals. The island's food sources, in particular the cacti on which the iguanas feed, are declining — another reason why some iguanas were transferred to Santiago Island. How iguanas came to reach the Galápagos thus remains a mystery; we hope, however, that they may continue to populate these islands for a long time to come, helping to make them unique in the world.
