Saving the Mangrove Finch from Extinction

Perhaps one of the most famous birds in the scientific world, the Darwin Finch was made world-renowned following the publication of Darwin’s theory of evolution by natural selection in 1859. There are around 13 species of Darwin finch, each demonstrating ever-so-slight behavioral and physical variations in accordance with their habitat, making them an excellent example of the theory. However, the finch populations, particularly the Mangrove finch, have been suffering in recent years. Thus, in 2014 the Charles Darwin Foundation initiated a rearing and repatriation program to protect and hopefully increase the mangrove finch population sizes.

Mangrove finch

Excellently adapted to their environment, mangrove finch populations had thrived for several millennium, particularly on Isabela and Fernandina islands; however, a study conducted in 2011 revealed that the global population of this brown little bird had dropped to just two small mangrove patches on Isabela Island. Such reduced populations (approximately 100 birds), in addition to low reproduction rates put the bird in serious danger of extinction due to potential environmental changes, disease, etc. The bird was thus classified as Critically Endangered on the IUCN Red List of Endangered Species.

 

Threats to the population

Galapagos finchesUnfortunately, like many species in the Galapagos Archipelago, mangrove finches have suffered increasing stress from more intense climatic events, introduced species and disease. One of the most significant causes of their decline is the parasitic fly, Philornis downsi. This introduced fly lays its eggs on incubating birds so that its larvae can feed on the blood of the helpless newborns. This leads to extremely high levels of nestling mortality and was the second leading cause for nest failure during the 2012/2013 breeding season, at a 17% occurrence rate following abandoned eggs (29%). This entire season had a troubling nesting success rate of only 33%. The bird populations have also suffered at the hand of the introduced black rat populations, which have been preying on the birds’ eggs and nestlings. These factors and also cases of interbreeding with the woodpecker finch are weakening the population’s gene pool, thus making it significantly more vulnerable to extreme changes in weather patterns and introduced diseases. It is quite possible that one single outbreak of disease or instance of extreme weather could wipe out an entire population.

 

Humans Giving Back

Following the 2011 study, the Galapagos National Park (GNPD) and Charles Darwin Foundation (CDF) launched highly successful programs to increase population sizes and minimize the threats the bird faces. These included rat monitoring and control programs as well as a variety of conservation management techniques in order to determine the most effective methods to ensure the survival of the mangrove finch population.

In culmination of these studies and programs, the Charles Darwin Foundation initiated a mangrove finch-rearing program in 2014. At the end of the first year, 15 fledglings were released into the wild, with two more groups released onto Isabela during the subsequent two years, the latter of which took place on April 26 of this year. 15 more finches (making a total of 36 birds) were released onto Playa Tortuga Negra on Isabela Island. In order to increase the success of the release, the birds were moved to a pre-release aviary three weeks prior. Several items from the surrounding environment were included in the aviary to encourage the birds to forage before being released, such as foliage and fallen trunks.

Nothing Like Results

In order to monitor the birds following their release, miniature radio transmitters were attached to each one. Due to their small size, the batteries only lasted a few weeks; however, during this time, the birds were found interacting with wild-born individuals of the same species, and they also exhibited similar foraging behavior as the wild-born individuals. Eight of the released birds were even observed flying approximately 1.5 km away from the aviary during foraging trips.

Once the trackers were removed, experts continued to look out for the birds and, although a difficult task due to the mysterious nature of the birds, several of the individuals released over the previous two years have been spotted, thus proving that the mangrove finches born in captivity are able to survive long-term in the wild, which is excellent news for the foundation.

For those interested in learning more about these breeding and repatriation programs, the Charles Darwin Research Station has an excellent info booth where visitors can watch footage of the programs and observe maps and other visual displays. The recently renovated facilities are currently open, and the new visitor complex will be fully operational by mid-October of this year.

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