Giant tortoises return to the Galapagos Islands after nearly 200 years

It is a historic return – this is how rangers from the Galapagos National Park commented on the reappearance of giant tortoises on the islands. The reintroduction of these reptiles was made possible thanks to efforts undertaken in a special breeding program on Santa Cruz Island. On one of the islands – Floreana – more than 150 representatives of this remarkable species will appear, meaning their number will exceed that of the people living there.

Not descendants, but successors of the native species

When Charles Darwin arrived in the Galapagos archipelago, the population of Chelonoidis niger niger reached 350,000. This native species became completely extinct in 1840. It happened due to sailors who took tortoises with them to eat their meat during long sea voyages.

Many indications suggested that the species Chelonoidis niger niger would never be restored. Everything changed in 2008, when scientists discovered that tortoises on Isabela Island originated from the same genetic lineage. The local population became the basis for establishing a hybrid breeding program – scientists crossed tortoises from Isabela Island with tortoises from Floreana Island. In this way, out of 23 genetic combinations, they selected those most similar to those possessed by the extinct species.

By 2025, around 600 tortoises had been bred as descendants of those exterminated. Some of them are already mature enough to live independently in natural conditions.

The restoration of the ecosystem on Floreana Island has reached an important milestone. This week, 158 captive-bred giant tortoises were released into the wild – announced the Galápagos Conservation Trust.

The return of giant tortoises – a step toward restoring natural conditions on the island

Among the islands of the Galapagos archipelago, Floreana was particularly affected by the impact of civilization. It was a destination for pirates and whalers. For some time, it even served as a prison. The consequences of exploitative practices and the thoughtless introduction of alien species into the island’s ecosystem, around 1,600 in total, are still visible today.

Ecuadorian authorities and non-governmental organizations are carrying out a large-scale project to restore natural conditions on Floreana Island. It is an expensive undertaking – its total budget amounts to 15 million dollars. The measures include, among others, the reintroduction of native plant species and the implementation of new spatial management standards. However, for the project to succeed and for the giant tortoises to have safe living conditions, it is first necessary to remove invasive species from the island as quickly as possible.

This has already been achieved in the case of goats – the last one disappeared from the island as early as 2007. A major problem remains the presence of rats and cats, which pose a threat to birds and small animals. Fortunately, their numbers are decreasing, which has led to an increase in the local bird population, and after 200 years the Galapagos rail has returned to the island. Farmers are also noticing positive changes – thanks to the removal of rats, crop yields have increased by 80 percent.

However, restoring Floreana Island to nature will not rely solely on removing alien species. The goal is also to increase biodiversity, and giant tortoises will play their part in this. Like landscape architects, they will transport plant seeds, expanding their range to new locations.

Will captive-bred giant tortoises cope in natural conditions? No one knows the answer to that question. The released animals will be constantly monitored. As Martin Wikelski from the Max Planck Institute of Animal Behavior explains, miniature location-monitoring sensors based on the Starlink system have been attached to the shells of 50 tortoises. Over the next 10 years, they are expected to provide scientists with valuable information about the course of the reintroduction.