From Galapagos News: European Version, Issue 23, Fall 2006
by Glyn Young

An Update on Major Funding for the Mangrove Finch

A year ago, in issue 21 of Galapagos News, I discussed the status of the mangrove finch, a bird that is special even by Galapagos standards. This unobtrusive finch is today restricted to two tiny patches of mangrove forest on Isabela’s west coast, where it survives with a population of maybe no more than 100 birds. Last year’s article ended with an outline of work planned for the conservation of this finch and it is with excitement that this can now be updated.

The Durrell Wildlife Conservation Trust, in partnership with the Charles Darwin
Foundation and the Galapagos National Park, applied to the Darwin Initiative, a
British Government environmental programme, for funding. In March 2006 we learned that this application was successful and will receive funding for three years starting this year. An important aspect of this grant is that the Darwin Initiative money – £173,500 in total – funds the employment of an experienced scientist to take charge of all fieldwork throughout the project.

The field manager, Birgit Fessl from Austria, has now been appointed. She will
operate in pretty inhospitable terrain: Isabela’s isolated mangrove forests (or
‘mangles’) are surrounded by formidable lava fields, can only be approached from the
sea, and have no fresh water. The ‘mangles’ are a remarkably dense forest of tree roots and branches but are pleasantly cool and shady. It is in this tangled habitat that the finches live, foraging below the bark of the trees and amongst the accumulated leaf litter and fallen branches. It is possibly this leaf litter that makes these mangroves
unique: in more typical mangrove areas the tide washes this material away, or the many crabs living in the area eat and bury it.

However, the mangroves at Playa Tortuga Negra and Caleta Black are separated from the sea by dunes and, while seawater seeps under the dunes with the tides, material cannot be washed away. More difficult to explain is the near complete absence of crabs in the mangroves. There are hermit crabs at the dune edge but these do not venture far inside.

Over the next three years, research will determine the ecology of the finch and discover how much time is spent foraging on the trees and how much on the leaf litter where it is vulnerable to predatory introduced mammals such as rats and cats. The exact finch population will be established, along with territory size, social structures including relatedness of individuals, nesting habits, and diet, etc.

It is also hoped that answers will be found to a question that has long puzzled our expert project consultant, Hernan Vargas. Why, in Playa Tortuga Negra, do the finches apparently prefer nesting in black mangrove trees, instead of the more common red mangrove, yet in nearby Caleta Black, which lacks black mangroves, they use red mangroves?

It will also be Birgit’s job to investigate the impact of invasive flies on the nesting and survival of the finches, and to find ways of controlling this threat, something she has already been looking at. The possibilities of captive breeding some finches will also be investigated and, at a workshop later in the project, research results and techniques developed will be used to ensure that this remarkable bird survives.

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