Finches were one of the many birds Darwin studied in the Galápagos Islands before publishing his monumental work on natural selection. Today, the mangrove finch is on the verge of extinction in the Galápagos. There are around 100 left, with just 20 breeding pairs. To keep the finches from disappearing altogether, the Charles Darwin Research Station and San Diego Zoo have engaged in a captive breeding program.
Recently, a third group of fledging mangrove finches were released on Isabela island. All birds are fitted with miniature tracking devices. Some returned to the aviary, but several finches released in past years have been seen in the wild. This showed finches raised in captivity are able to survive long-term.
The biggest threat to mangrove finches is a parasitic fly larvae which has caused high mortality rates among offspring. During four months of caring for the chicks, the project team developed techniques to develop their skills necessary for survival in the wild. After the chicks could feed themselves, they were transferred to pre-release aviaries in the mangrove forest of Playa Tortuga Negra. To prepare the birds for release, their cages were adapted to resemble the wild. When the chicks were able to feed themselves for 4-6 weeks, the technicians opened the aviary so the finches could leave of their own accord.
Now a group of international experts from various science institutions are conducting studies on genetic variation, songs and diet of finches on Santa Cruz island. They are looking at things such as the variations in beak sizes. They also want to see how the introduction of human food has changed the diet of the finches. Preliminary data suggest there are important differences in behavior and diet at various sites. This project is run in partnership with the Ministry of Environment, Galápagos National Park and the Charles Darwin Foundation. It has financial support from the Earthwatch Institute.
Research done by Peter Grant of Princeton University showed that Darwin’s finches are descendants of a single lineage of birds that came to the islands from the American continent and, over time, evolved to fill the various ecological niches present in the archipelago. That research also found changes in the beak sizes of finches over just three decades. This change is partly due to weather — the level of rainfall is important for finches that feed on seeds. After the dry season, the finches that survived drought had slightly wider beaks. Galápagos National Park says there are 14 species of finches on the islands (see our Infographics page).
For birdspotting tours as part of a cruise, or island-hopping, or a single hotel stay, see our Happy Gringo Galapagos options and consult with our travel advisors for prices and availability :)