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10/02/2022 Invasive species

Mangrove Finch Project update

Despite the challenges of the ongoing pandemic, the Mangrove Finch Project team was able to spend six weeks in the field during the 2021 breeding season. Some new techniques provided some valuable results.

Photograph of Francesca Cunninghame

Francesca Cunninghame

Francesca Cunninghame is Principal Investigator at the Charles Darwin Foundation working on the Mangrove Finch Project.

The mangrove finch is the most endangered bird in the Galapagos Islands and although intensive conservation efforts have been carried out for over a decade, the species still relies on human intervention to enable successful breeding. Since impacts of the COVID-19 pandemic were first felt in early 2020, the Mangrove Finch Project run by the Charles Darwin Foundation (CDF) and supported by Galapagos Conservation Trust, had to abruptly stop its activities. The team’s conservation efforts continue to be compromised with limited personnel being able to travel to the Galapagos due to some continuing international travel restrictions. However, despite these challenges, the dedicated field team was able to spend six weeks in the field during the 2021 breeding season and combined with some new techniques provided some valuable results.

A mangrove finch @ CDF Juan Manuel García

Mangrove Finch Project outcomes in 2021

While the known fledging success has been low over the past two seasons (2020: unknown, 2021: > 3 fledglings), the adult population has remained stable. With the support of GCT and in collaboration with the Galapagos National Park Directorate (GNPD), the team continue to dedicate efforts to enabling higher breeding success with chick survival still significantly reduced due to impacts from the introduced avian vampire fly (Philornis downsi). While the team are successful at controlling introduced rats (Rattus rattus), impacts from the larvae of the avian vampire fly continue to cause extremely high nestling mortality if humans do not intervene.

Mangrove finch nest injections

After four years of head-starting, where 39 juveniles were released into the wild, recent efforts have focused on protecting chicks without having to remove them from their natural environment, enabling them to fledge with the adults with whom they spend up to a month being introduced to foraging sites. The team have adapted nest injections, whereby a small amount of an organic insecticide is carefully injected into the base of mangrove finch nests, aiming to kill and or reduce the number of fly larvae in the nest without coming into contact with eggs or chicks inside the nest. This requires challenging tree climbing to enable people to access nests that are usually high up at the tips of flimsy branches, all done in a restricted time limit to ensure we do disrupt the incubation or chick-rearing cycle of the birds. Although we have trained several Ecuadorians, including Galapagos National Park Directorate (GNPD) rangers in these techniques, with onsite training each season, we are currently upskilling the locally based team with an arborist course taking place on Santa Cruz island from an Ecuadorian provider. Three CDF team members and six GNPD rangers took part during January 2022. This will give the team a stronger background in climbing techniques to help assist them in the more challenging climbing techniques required to access mangrove finch nests. Additionally, the team are looking into the feasibility of trialling a remotely activated spraying device to treat the outside of mangrove finch nests, reducing the need for people to access nests.

Nest injection are carefully used to treat mangrove finch nests @ CDF Juan Manuel García

Mangrove finch nest material dispenser trial

The project has been investigating the potential of nest material dispensers with the aim of mangrove finches taking insecticide treated nest material to the nest themselves, reducing the need for humans to access nests. While this technique has been successful for other species both globally and within Galapagos (encouraging results came from the 2021 trials with other Darwin’s finches and little vermilion flycatchers on Santa Cruz, led by CDF’s Landbird Conservation Project), to date mangrove finches have not been recorded showing any interest in the nest material dispensers that have been put out in their habitat and no mangrove finch nests have been found to contain any of the material. This likely reflects they are highly specialised in their environment, with the female lining the nest with carefully masticated mangrove tree sticks. However, we are hopeful that with time mangrove finches will come to recognise the dispensers as another source and we are currently carrying out trials in the field which will be intensified this coming season.

Francesca Cunninghame, along with one the team´s researchers, looking for mangrove finch nests at different heights between the trees. @ CDF Juan Manuel García

Mangrove finch supplementary feeding trial

Likewise, supplementary feeding trials will continue for the third season. Encouraging results from 2020 and 2021 have shown that a few hand-reared birds come to the feeding stations with one female provisioning her chicks in the nest. We hope that this will have a double impact to both better condition females to come into breeding condition (each season many solitary males build display nests and sing all season never securing a mate while several females do not breed) and enabling nestlings to be better provisioned thus increasing their resistance to any parasitism.

Mangrove finches and the surrounding habitat

After suspecting a decline in habitat quality in the tiny 30-hectare area of mangroves where the remaining mangrove finch population is found, the team have formed a collaboration with Dr Feller from the Smithsonian Institute. Dr Feller was able to join us in the field in 2020 and it opened our eyes to a whole different perspective of the site, where previously we have been more focused on the birds. The mangroves that the mangrove finches currently depend on are tiny and unique and we have initiated long term monitoring to better understand the drivers of the systems on which these forests rely, we feel this is important as we grapple with the potential negative impacts climate change could throw at the mangrove finches. Although an island-wide habitat survey is not possible this coming season, the team look forward to continuing with this wide-ranging work that adds an essential element to our future conservation planning.

The precarious status of the mangrove finch highlights the importance that conservation intervention can continue and while the pandemic brought temporal relief for some native species as humans reduced their presence in wild areas, the mangrove finch requires our help during the breeding season and consequently has suffered, as many of us have personally, due to COVID-19 and the corresponding restrictions.

Ways you can help

Please help GCT’s efforts to conserve the mangrove finch, and other endangered species of Galapagos in these unprecedented times by donating to our work.

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