The Galapagos land iguana is one of three species of land iguana found in Galapagos. This large yellow lizard lives in the arid zone on a number of islands, but went extinct on Santiago in the early 20th century. The reintroduction of these missing herbivores will help Santiago’s damaged ecosystem to heal by thinning out dense vegetation, breaking up compacted soil and spreading seeds around the island, creating opportunities for other species to thrive.
7
major islands where Galapagos land iguanas are endemic
9
of 12 populations suffer from feral cat predation
> 5 k
iguanas have been released on Santiago since 2019
187
years after extinction, land iguanas began breeding again on Santiago
The Galapagos land iguana (Conolophus subcristatus) is currently classified on the IUCN Red List as Vulnerable. The species had been extinct on Santiago island since the early 20th century, most likely due to introduced animals such as feral cats and goats (which have now been removed from the island). Land iguanas are ‘ecosystem engineers’, shaping their environment by grazing on vegetation and stopping it from becoming too dense, as well as spreading seeds and digging up soil, which helps to create opportunities for new plants to grow. Without the iguanas, the ecosystem on Santiago would be unable to fully recover from the damage done by invasive species. These introduced animals are also continuing to cause decreases in land iguana populations on other islands in Galapagos by competing for food and by eating eggs and juveniles.
By tagging individual land iguanas, the project team, led by Dr Luis Ortiz-Catedral, gathered as much data as possible to assess the population size and health status across Fernandina, Isabela and Santa Cruz islands. This provided the information needed to reintroduce land iguanas to Santiago, and in 2019 the Galapagos National Park Directorate and Island Conservation released 2,500 land iguanas on Santiago. Further releases in the years since mean that more than 5,000 iguanas have now been reintroduced.
The reintroduction aimed to boost the survival of Galapagos land iguanas, but also to help restore Santiago’s ecological health. The land iguanas were translocated from North Seymour island where there were over 5,000 individuals, a substantial population for an island this size, which has led to a reduction in the island’s vegetation.
In 2022 experts from Galapagos National Park and scientific advisors returned to Santiago, three years after releasing 2,500 iguanas on the island. The team were delighted to find breeding taking place and new juvenile iguanas, of various ages, on the island, showing that the species was reproducing successfully. The island has already begun to show positive changes due to the reintroduction, with the iguanas opening up paths, removing soil and dispersing seeds. There is now more food for other species, and the reintroduction has been deemed such a success that other endemic species such as Galapagos hawks are likely to return in the next few years.
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The project team will continue to monitor the individuals released onto Santiago to ensure that the population thrives. The next phase of the project is an Archipelago-wide land iguana survey and census in Galapagos. This census plans to investigate the health and key threats to the population at a multi–island level, including some additional sites that have not been assessed before such as Fernandina and Volcán Ecuador on Isabela.
With your support, we can restore nature across the Galapagos Archipelago and bring back more missing wildlife.
