Good news from the Galápagos Islands! Ten years after the removal of invasive rodents from two of the archipelago’s islands, native birds and geckos are thriving.
In late November, researchers with Galápagos National Park and Island Conservation visited Rábida and Pinzón Islands to document wildlife recovery on the islands. Pinzón has an area of 18 sq. km. (about 7 sq. miles), and Rábida measures almost 5 sq. km. (1.9 sq. miles). Both are located in the center of the archipelago and east of Isabella Island, the largest island of the Galápagos.
On Pinzón, the team found a healthy and growing population of Galápagos Rails (known locally as Pachays) in the upper part of the island. The rail — an endemic bird that is known from seven other Galápagos islands — apparently colonized the island only recently. (One other record of the species is shown on eBird, from December 2021, when three individuals were spotted.) The researchers believe that the rail could have migrated from Santiago Island and found Pinzón to have ideal habitat to establish itself.
The international Red List classifies the rail as vulnerable and estimates its total population at 3,300 to 6,700.
The team also had frequent sightings of Common Cactus-Finches. This species, which is found throughout most of the Galápagos, was absent from Pinzón for decades, with only a few reports on eBird since 2006.
On Rábida Island, a healthy population of geckos, known only from subfossil records dating back more than 5,000 years, have recolonized the island.
Other bird species the team tallied include American Flamingo, Galápagos Hawk, and Little Vermilion Flycatcher.
Rodent removal works
For decades, invasive rodents devoured native species and destroyed the natural ecosystems on Pinzón and Rábida.
“The management measures implemented on these islands in recent decades have been effective and today we can see the results. The islands have once again become the habitat of endemic species of great importance to the ecosystem,” said Danny Rueda Córdova, director of the Galapagos National Park. “On Pinzón, the Giant Tortoises returned to nest after more than 150 years. Because of our work to remove invasive rodents, the population now reproduces naturally without human intervention.”
The technical team, led by park rangers from the Galapagos National Park Directorate and Island Conservation, with support from the Jocotoco Foundation and the University of Idaho, arrived on the islands on November 21, and, over the course of eight days, evaluated reptiles, land and sea birds, snails, and plant cover on both islands. Various methods were used to monitor and count the presence of endemic or native species to estimate their population sizes. Over the coming months, the team will use this data to determine the degree of ecological restoration that these two islands currently maintain by comparing it to similar data collected prior to removal of invasive rodents.
“It is extraordinary to see the change that has taken place on these two islands in the last decade without the presence of rodents, which affected the reproduction of many species of reptiles and birds,” said Paula Castaño, native species manager at Island Conservation. “It is inspiring to see how new species establish themselves and how species that were present, such as the Galápagos Hawks, reproduce successfully and are colonizing new territories and fulfilling their role as top predators, maintaining the balance of the islands’ ecosystem.”
Thanks to Island Conservation for providing this news.