With less 100 individuals alive today, mangrove finches are the most endangered birds in the Galapagos Islands. These finches are not part of some wider colony, but represent the entire world population. There has not been a bird extinction in Galapagos since before Darwin’s time and a project to save the Mangrove Finch supported by the Galapagos Conservation Trust is aiming to ensure this continues.
The mangrove finch is one of fifteen species of Darwin’s Finches and one of the rarest birds in the world. The species is endemic to Galapagos and although they once occupied a number of mangrove sites on Isabela and Fernandina, these tiny brown birds are now only found in two small patches of mangrove forest on Isabela, with a combined size of just 32 hectares. The birds are classified by the International Union for Conservation of Nature (IUCN) as critically endangered.
The fight against parasitic fly Philornis downsi
For nearly ten years since 2006 the Mangrove Finch Project has focussed on increasing our understanding of the biology and ecology of these birds and the threats they face. Whilst the exact cause for the reduction in the geographical range that this bird is found is unknown, the threat to their population is primarily due to introduced species, most notably the parasitic fly Philornis downsi. Adults of this fly are harmless, but as larvae they suck the blood of the mangrove finch nestlings, frequently resulting in their death. But this isn’t the only threat; predation of the eggs by black rats, decline in genetic diversity of the small population and increase in climatic variability are also significant.
The Galapagos Conservation Trust is helping to fund the multi-institutional Mangrove Finch Project, which aims to boost the mangrove finch population before it is too late.
January 2014 saw the start of an exciting new phase in the project, which resulted in the team successfully raising 15 mangrove finch chicks in captivity and releasing them back into the mangroves.
Mangrove finches are the earliest breeding species of Darwin’s finch. They breed during the wet season (December to April), nesting high up in the mangroves and lay up to five clutches each year.
Breeding success is very low in the first few months of the season, partly due to predation by introduced species, but if a nest fails the adult finches will begin to re-nest immediately for as long as the rains continue.
The Mangrove Finch Project is working to boost the birds’ numbers by turning this into an opportunity. By collecting eggs from the first clutch and hand-rearing them at the Charles Darwin Research Station before releasing them back into the wild, the project team are able to give the chicks a head start in life without the threat of the parasitic fly.
Given the success of the first season of the head-start project, The Galapagos Conservation Trust launched their Mangrove Finch Appeal in April 2014 to raise funding for the 2015 season.
This was their most successful appeal and meant that they were able to provide some of the necessary funding for the second season. Recently broadcaster and naturalist Chris Packham got behind the appeal to raise a further £72,000 to fund the next 12 months of the project.