With around 100 individuals remaining in the world, the mangrove finch is the most endangered bird in Galapagos. Whilst habitat destruction has played a role in their decline, the primary driver has been the introduction of non-native species, such as rats and the invasive fly Philornis downsi. After controlling rat populations around nest sites for a number of years, the number of successful fledglings has increased.
Philornis downsi, however, has continued to reduce numbers of mangrove finches. While the adult fly is harmless, the larvae suck the blood of young chicks, often causing death. The Mangrove Finch Project, carried out by the Charles Darwin Foundation and the Galapagos National Park Directorate in collaboration with San Diego Zoo Global, Auckland Zoo and Durrell Wildlife Conservation Trust, is leading the fight against P. downsi to prevent this iconic bird from going extinct and the Galapagos Conservation Trust are one of the key funders of the project.
To date they have trialed two approaches to protect young mangrove finches from P. downsi; captive hand-rearing of chicks and pesticide nest injections in the wild. Both techniques have proved promising, with 2017 seeing the first evidence of hand-reared chicks breeding in the wild and the survival of 14 fledglings from injected nests.
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In early February 2018, the team headed to the coastal mangrove forests at Playa Tortuga Negra on Isabela island to conduct population surveys and administer injections for roughly eight weeks. During the surveys, the team have been keeping an eye out for any hand-reared chicks to assess the numbers successfully breeding in the wild.
Meanwhile, project partners at the San Diego Zoo have been conducting an in-depth review of the head-starting programme, which has released 39 fledglings since 2014. At the end of the field season, the two techniques will be comprehensively reviewed, which will inform management strategies for the upcoming years. Whilst mangrove finches remain critically endangered, the round-the-clock dedication of the team is helping to ensure the future of this iconic species.
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The Mangrove Finch Project is a bi-institutional project carried out by the Charles Darwin Foundation and the Galapagos National Park Directorate in collaboration with San Diego Zoo Global, Auckland Zoo and Durrell Wildlife Conservation Trust. The project is supported by the Leona M. And Harry B. Helmsley Charitable Trust, Galapagos Conservation Trust, Marguerite Griffith-Jones, GESS Charitable Trust, Decoroom Limited, Holbeck Charitable Trust, and Friends of Galapagos Switzerland.