By guest author Birgit Fessl, Coordinator of Galapagos Landbird Research for the Charles Darwin Foundation.
I first came to Galapagos in December 1995 to assist on the PhD project of Sabine Tebbich, who was studying tool use behavior of the Woodpecker Finch. I was doing a PhD myself at the time, but Galapagos was a dream destination for me and I gave this trip priority. I never imagined that more than 20 years later I would be leading research to conserve the landbirds of Galapagos!
During field trips to Galapagos with Sabine, two important things happened:
We discovered the parasitic fly Philornis downsi — by chance. This nasty fly was accidentally introduced to Galapagos in the 1960s and became established without anyone noticing, until we found its blood-sucking larvae in a Woodpecker Finch nest. As we investigated further, we found it in nests of other bird species. To date, it has been found in the nests of 18 native or endemic landbird species in Galapagos. One of the priorities of the Galapagos Landbird Conservation Program, a bi-institutional program of the Charles Darwin Foundation (CDF) and the Galapagos National Park Directorate (GNPD), is to find a method to protect birds from these deadly parasites.
Secondly, while collecting information on the density of Woodpecker Finches living in the different vegetation zones of Santa Cruz, we realized that surprisingly very little was known about how many birds are found on each island. Despite extensive studies on the breeding biology and evolution of Darwin’s finches and other birds, no one had actually counted them!
Without knowing how many birds are out there, how could we know if population numbers were healthy or in need of some kind of conservation action? Establishing a baseline for bird densities on each island and setting up a long-term monitoring system was thus essential and a priority for the Landbird Conservation Program. Galapagos Conservancy and other partners also recognized this and provided much needed financial support, enabling us to make significant progress toward achieving our goal.
We use the point count method for estimating the density of birds. This involves recording all singing birds that you hear in a 5-minute interval and estimating their distance from the listener. This required everyone to learn the different song types and dialects of Galapagos landbirds. However, even after we learned them, identifications were often challenging — especially when birds were far away or when bird songs varied by island. To ensure correct identifications on each and every monitoring trip, our team of counters spends the first day or two of every trip together, to test our skills and make sure that our bird identifications coincide.
Now, for the first time, we have baseline data for all passerine species and most other landbirds from San Cristóbal, Floreana, Santa Cruz, the highlands of Santiago, and Sierra Negra volcano on Isabela, as well as some of the smaller islands. We began our work on the inhabited islands, as that is where the most serious declines in population numbers are occurring. Our goal over the next few years is to carry out surveys in the remaining islands of the Archipelago.
The data collected in these surveys are already providing insights into the status of bird populations and what we need to do to protect them. For example, because of the data collections begun during Sabine’s thesis, we have discovered that several small, insect-feeding bird populations have severely declined on Santa Cruz. The IUCN threat status of three of these species has been upgraded, and we are now working intensively with the GNPD to reverse these declines.
Dr. Birgit Fessl has been studying landbirds on the Galapagos Islands for more than 20 years and has extensive experience in bird ecology, bird monitoring and host-parasite interactions, with a special focus on the impact of the invasive bird nest parasite Philornis downsi. Since 2014, and in partnership with the GNPD, CDF ornithologists, and collaborating scientists, Birgit has been coordinating priority actions outlined in the Landbird Conservation Plan, including the evaluation of the conservation status of landbird populations, the identification of the principal threats they are facing, the development of management actions, and a citizen science component to enhance monitoring efforts.
Galapagos Conservancy has been supporting the Charles Darwin Foundation’s Landbird project since 2013.
Read more about the conservation of landbirds in Galapagos.