Darwin’s Finches More At Risk Than Ever

In a scientific paper published today, scientists from the University of Utah created a mathematical model to predict how the invasive fly, Philornis downsi, will impact on the finches of Galapagos in the long term; and the findings are worrying…

The study

Philornis downsi is an invasive, parasitic fly that was first documented in Galapagos in the 1960s, but not found in nests until the 90s. The larvae of this fly feed on the young chicks of many Galapagos land birds, resulting in high levels of chick mortality.

The researchers used 5 years’ worth of data to project the impact of the fly damage on finch reproduction rates, to assess the future likelihood of the finches’ survival.

In two of the three scenarios that they modelled, the finch populations were declining and at risk of extinction. In the worst scenario the scientist found that the finches may succumb to this pest within 50 years.

However, there were also positive findings from the study. The findings showed that if the probability of infestation is reduced, then the risk of extinction is also significantly alleviated.


The researchers argue that if the number of infected nests could be reduced by 40% then the risk of extinction would essentially be lifted.

Tackling Philornis downsi

Present on 14 islands and frequently causing up to 100% nestling mortality, immediate management actions are necessary. If the number of flies can be reduced, then there is a good probability of saving Darwin’s finches from extinction.

Research into effective control of Philornis downsi must be the focus for future conservation efforts.

In 2012, GCT co-funded an international workshop for international experts, local organisations and authorities, and current researchers working on Philornis downsi management to identify what management tools are available.

There are a number of potential methods of eradication that are being testing in Galapagos. Some of these include the introduction of fly-parasitising wasps as biological control, the use of cotton balls containing pesticides which the birds can use to line their nests, and fly trap attractants.

As the researchers try to find an effective management system, the best solution for ensuring the survival of these birds, is hand-rearing chicks in captivity.

Mangrove finches

GCT is the principal funder of the Mangrove Finch Project, a crucial conservation initiative to save Galapagos’ rarest bird from extinction. 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. The project has continued into 2015, with 8 more chicks hand-reared and released back into the wild.

Blog, Mangrove Finch Feeding © Liza Díaz Lálova CDF

This project is more important than ever now we know severe the future looks for Darwin’s finches if a solution to Philornis downsi is not found soon. We must continue to ensure the Galapagos’ most endangered bird does not go extinct before the threat of Philornis downsi is removed. A bird has not gone extinct in Galapagos since Darwin’s time, and we cannot let it happen now.  

How you can help

With the threat of extinction looming closer, we need to raise the funds to secure the Mangrove Finch Project for another season. Please make a donation here to help us ensure this project can continue in 2016, and more mangrove finches can be hand-reared and re-released into the wild to boost the population.