Darwin’s Land Birds Appeal Blog Series – Part 2

Welcome to the second blog in our Darwin’s Land Birds Appeal series, this time focusing on the critically endangered mangrove finch.

The mangrove finch belongs to the group of birds commonly referred to as ‘Darwin’s finches’, named after their role in the development of Darwin’s theory of evolution through natural selection. As with many land birds in Galapagos, it is endemic to the Islands, meaning it can be found nowhere else in the world!

Mangrove finches have a dull brown plumage, becoming more olive-toned towards their tails, and have whitish, lightly streaked underparts. After several annual moults, males develop black feathers on the head and neck. They have a long, pointed beak, which as with many of Darwin’s finches, has evolved to forage for specific foods. This species, for example, uses its delicate beak to lift up the scales of bark on trees to find insects beneath, as well as to probe through leaf litter.

Once found throughout mangroves on Isabela and Fernandina, today the species lives only in two small areas of pristine mangroves on these islands.

Galapagos Wildlife: Mangrove Finch © Michael Dvorak

The underparts of the mangrove finch has lightly coloured streaks © Michael Dvorak

It is one of the most range-restricted birds in the world, with only around 100 individuals remaining in an area with a combined size of just 32 hectares. Whilst historic reasons for their declines remain unknown, invasive species are the main threat to mangrove finches today. These include rats that feed on their eggs and young birds, as well as Philornis downsii, a fly whose larvae feeds on young birds in the nest.

Galapagos Wildlife: Philornis downsi © Sarah Knutie

The larvae of the invasive Philornis downsi fly feed on the blood of young birds © Sarah Knutie

While the threats to this bird are severe and their numbers are critically low, the Mangrove Finch Project team at the Charles Darwin Foundation, in partnership with Galapagos Conservation Trust (GCT), has worked tirelessly to save the species. Over the last few years, using a captive rearing programme, whereby young birds are removed from wild nests and hand-reared in the absence of P. downsii larvae, 39 birds have been added to the wild population. When considering that the species only has 20 breeding pairs, this is a major triumph.

Mangrove Finch Fledgling © Rich Switzer

A mangrove finch fledgling being hand-reared before its release into the wild © Rich Switzer

Other measures to protect these birds are in place, including treating nests with insecticide to kill P. downsii larvae in the wild. This is a more cost-effective, less time-consuming method and trials will continue into the next field season in 2020. However, to make matters worse for the mangrove finch, in recent years their preferred mangrove species for nesting, the black mangrove, is in decline. Work is ongoing to understand the cause, but this only adds to the need to raise funds to help protect this critically endangered bird.

Help save the mangrove and Darwin’s land birds today!

We have a number of projects that will benefit from your kind support, including the mangrove finch, Floreana mockingbird and vermilion flycatcher projects, so donate today to help save Darwin’s land birds.

Other ways to help the land birds of Galapagos!

Why not purchase one of our land bird-themed t-shirts, jumpers or bags? Alternatively, spread some Christmas cheer with our vermilion flycatcher Christmas card or gift someone a Floreana mockingbird adoption!