The Galápagos Archipelago has a high level of endemics - species that occur nowhere else in the world. For this reason, and because one can watch evolution happen "before your eyes", the Galápagos are considered a living laboratory of evolution. The islands have been free of parasites until the last two decades and hence the land birds are unadapted to the ravages of parasites and have few defences. The adults of the introduced fly we are studying are harmless vegetarians and were probably introduced with fruit imported into the island for the growing tourism industry. Unfortunately the fly lays its eggs in bird nests and after hatching the larvae feed on the blood and tissues of nestling birds, like Darwin's Finches. The fly larvae were first discovered in Darwin Finch nests in 1997 and since then the populations of many species have declined by 40-80%.
The focal species in this project is the Critically Endangered Medium Tree Finch that has a total population of about 1600 birds that are only found on one island, Floreana. Thus the only location relevant to this species is Floreana and this project is essential for preventing its extinction. Nevertheless, the project is also highly relevant to the other 13 species of the iconic Darwin's Finches, all of which are endemic to the Galápagos Archipelago. Similarly, the other land birds in the Galápagos are also largely endemic and hence at risk of extinction from the parasite, though many of them such as the Galápagos Mockingbirds are larger and suffer lower rates of nestling mortality.
The project is also important in a wider international context because the globalisation of world trade and tourism means that introduced parasites are a new conservation threat in many countries. The strategies we develop in the Galápagos Archipelago for dealing with the lethal parasitic fly and conserving endangered birds are thus likely to be highly effective in these other countries. Our project in the Galápagos is an ideal model system because the fewer species on a remote archipelago means that there are less confounding variables in determining the impact of the parasite, and the unusual vulnerability of the host birds makes the effects more obvious.
In 2013, we plan to collect field and laboratory data to develop control measures for the fly. We will focus our data collection on the Medium Tree Finch. We will (1) test which finch parameters - like nest size, nesting density, host genetic population - are related to nesting success. (2) Importantly, we want to collect genetic samples from the flies in finch nests to compare our fly population with those on the mainland, with the long-term goal to develop a fly control using genetically altered strains. (3) We will actively communicate the results of our findings with international scientists and conservation organizations to implement effective control options. These strategies have broad general significance in other localities where introduced parasites and diseases are impacting the fauna.
Project 12254801 location - Ecuador, South America