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There are 28 small endemic landbirds in the Galapagos Islands, including the iconic Darwin finches (17 species) and charismatic mockingbirds (4 species). In spite of extensive studies on the evolution of Darwin’s finches and other birds, surprisingly little is known about how many birds are found on each island and whether populations are healthy.
Recent studies indicate that some bird populations are undergoing severe declines, in particular on the inhabited islands. Studies are underway to understand what is the cause of this decline. The reasons are multiple and include nestling mortality caused by the invasive parasitic fly Philornis downsi (the most serious threat), reduced food availability caused by habitat degradation, predation by invasive species (e.g. rats and cats and the Smooth-billed Ani), and introduced diseases.
To reverse these declines as quickly as possible, the Charles Darwin Foundation (CDF) and the Galapagos National Park Directorate (GNPD) formed the Landbird Conservation Program in 2014. This program counts on the help of Galapagos residents, visitors, and researchers from around the world and is investigating multiple options simultaneously for the protection of these iconic bird species.
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Over 90% of the Galapagos landbirds are endemic, which means that they are only found in the Galapagos Islands. These endemic and native species include:
Our studies are focusing on the smaller landbird species: 26 passerines, 1 dove and 1 cuckoo.
Establishing a baseline for bird densities and bird health on each island and setting up a long-term monitoring system is one of the priorities for the Landbird Conservation Program. Thanks to studies and surveys, we currently have a growing database for bird numbers on the larger islands of the archipelago. This data will allow us to assess the status of populations according to the IUCN Red List Criteria and identify species that require targeted efforts to ensure their long-term protection. In the future, these data will be compared with results from monitoring expeditions, allowing us to detect changes (positive or negative) in bird numbers.
To reverse species decline, we are studying the general ecology and breeding biology of the species to determine the factor or factors that are affecting the wellbeing of bird populations. The data and information that we are collecting is enabling us to develop tools and management plans to safeguard birds and reverse the declines of threatened species.
One of the main threats to the wellbeing of birds is the parasitic fly, Philornis downsi. This fly is invasive in Galapagos and probably originated from mainland Ecuador. Currently, it attacks 19 endemic landbirds and one bird that is native to the Galapagos and is seriously affecting the survival of several of these species. All but the bird species restricted to Darwin, Wolf, Española and Genovesa islands (where the fly is not found) suffer damage by this fly.
The main goal of this project is to ensure the long-term conservation of small Galapagos landbirds.
We have now collected baseline data on the status of small landbirds on 75% of the larger islands. Many populations have either declined or are already extirpated on some islands.
The status of small landbird populations is especially critical on the four inhabited islands: Santa Cruz, San Cristobal, Isabela and Floreana. For example, three landbird species have recently disappeared on Floreana Island. While, the last confirmed sighting of the San Cristobal Vermilion Flycatcher, a bird species that is only found on San Cristobal, was in 2008.
Insect-feeding birds and island-endemics species that occur on one single island are of special concern. Current efforts are focused on protecting species with threatened populations such as the Little Vermilion Flycatcher (Pyrocephalus nanus), Mangrove Finch (Camarhynchus heliobates) and the Galapagos Martin (Progne modesta).
The Little Vermilion Flycatcher has thriving populations in areas that have been restored, such as on Alcedo Volcano or Pinzon Island, but has significantly reduced populations in inhabited areas. For example, this bird is nearing extinction on Santa Cruz Island where it appears to be severely threatened by the invasive parasitic fly Philornis downsi and by habitat alteration.
CDF has been working with collaborators to develop a method to inject insecticide into bird nests to protect hatchlings from Philornis downsi. The aim is to target application to the base of nests where high concentrations of fly larvae are found, minimizing contact with bird eggs or chicks. This is quite challenging as nests are often out of reach requiring very long poles to inject the nest! Some improvements are needed, but we have already been able to significantly reduce parasite load and increase breeding success.
Concurrently, we are seeking ways to improve the habitat of the Little Vermilion Flycatcher through the control of invasive plant and vertebrate species. Cat and rat control reduces nest predation, but even more importantly removal of invasive blackberry allows birds access to the ground and the invertebrate community living there. Behavioral studies on Alcedo Volcano, where there is no invasive blackberry, suggest that the Little Vermilion Flycatcher prefers to hunt ground-dwelling insects from high perches – when you have dense stands of blackberry this is not possible!
Another endangered insectivorous species is the Galapagos Martin with less than 500 individuals. We know very little about its distribution, breeding biology and general health. The birds are highly mobile and cannot be counted easily. Their nesting sites, most often high up in cliffs, are mostly inaccessible. We have recently confirmed that this species is also parasitized by Philornis downsi. To study its ecology, we have set up three bird houses. If birds accept these houses for nesting, we will not only learn a lot about their breeding ecology but we will also be able to catch them to conduct health checks and band them for long-term monitoring.
Keywords: Monitoring, ecology, breeding biology, invasive species, habitat management
Galapagos National Park Directorate, Agencia de Regulación y Control de la Bioseguridad y Cuarentena para Galápagos (ABG), Ministerio de Agricultura (MAG), Escuela Superior Politécnica del Litoral (ESPOL) Ecuador, Universidad San Francisco de Quito – Galápagos Science Center, National Museum of Natural History (París), Saint Louis Zoo – Missouri, University of Bern, University of Connecticut, Cornell University, University of Massachusetts, Universidad de Málaga, University of Missouri - St. Louis, Syracuse University, University of Southampton, University of Vienna, Universidad de Ciencia de Vida - Viena.