By guest author Eileen Heyer, BSc MSc
As an enthusiastic biologist who’s in love with field work, I was excited to travel to the Galapagos Islands for the first time in 2017 to collect data for my master thesis, “Parental care in the small tree finch (Camarhynchus parvulus), in relation to parasitism and environmental factors”. I quickly became hooked on these enchanted Islands. Galapagos is a special place for anyone interested in unique species and ecosystems, as well as introduced species and their impact on natural habitats.
Each year since then, I have been drawn back to this fascinating archipelago. In 2018, a colleague and I monitored a population of Vermilion Flycatchers in the highlands of Isabela Island. The Vermilion Flycatcher is an endemic bird of the Galapagos Islands, which has gone extinct on Floreana and San Cristóbal Islands and is rapidly declining on Santa Cruz.
This year, as part of the larger Vermilion Flycatcher Project at the Charles Darwin Foundation, I focused my fieldwork on the very small and continuously declining population in the highlands of Santa Cruz Island. Highly motivated with the hope of conserving this species, my colleagues and I began field work in early January at the beginning of the breeding season.
A study of habitat use in 2018 showed that the insectivorous Vermilion Flycatcher needs open areas for foraging. Unfortunately, nearly the entire understory of our study area at La Mina Granillo Roja was covered in dense thickets of the introduced blackberry (Rubus niveus). With the support from Galapagos Conservancy, the Charles Darwin Foundation cleared blackberry from five areas of one hectare each before and during this year’s field season, in collaboration with the University of Vienna and the Galapagos National Park Directorate, in order to improve the habitat by providing open foraging areas. This allowed for comparing the Vermilion Flycatchers’ use of these cleared areas with that of areas still overgrown with blackberry.
Each morning we headed out at sunrise, armed with binoculars and machetes, to continue the battle with the blackberry thickets and to look out for our target species — the elusive Vermilion Flycatcher. We searched for the flycatchers and their nests, controlled nests (by visiting marked nests and checking the status of each, including building, incubating, and feeding), treated nests with an insecticide against the blood-sucking larvae of Philornis downsi, collected abandoned nests and their eggs, and set up camera traps. In addition, we observed and documented both foraging and incubation behavior.
The work was not always easy. We fought with blackberry, sweated in the ever-increasing heat of the hot season, and worked on under heavy rainfall. But the tough conditions are part of what makes this such a unique experience, one I would not want to miss.
On some days, we returned home frustrated with little to show for our efforts, but on other days we celebrated the discovery of a new nest or some other success. It was a roller coaster of emotions. We’d spend most afternoons on data entry, preparing and constructing equipment, checking collected nests for larvae and pupae of Philornis downsi and for mites, as well as examining collected eggs for their fertility and reviewing the pictures from the camera traps.
We monitored the population until the end of the breeding season in April. Our observations show that Vermilion Flycatchers use the new open areas not only for foraging, but also as breeding territories. However, the long-term impact of habitat change often does not show in the first year. Continuing this study for the next few years will give us better insight into the ultimate success of blackberry control for the Vermilion Flycatcher.
After brainstorming with my colleagues, we concluded that there are several reasons for the decline of the Vermilion Flycatcher population in Galapagos. The birds struggle with infertility, interspecific competition (competition with other species for the same resources), predation, parasites, habitat change, and probably more causes that we are unaware of. Saving this population will require substantial conservation efforts over the next several years.
The Park will continue to control invasive plants in the five one-hectare areas, and we will continue to monitor the breeding success in the areas for at least two more years. We will also continue to remove parasites from accessible nests and investigate whether the birds are suffering from any other parasites in addition to Philornis.
There is still a lot to learn and understand about the Vermilion Flycatcher and its decline. I hope the project continues, and that we will successfully conserve this now very rare species on Santa Cruz Island.
Eileen Heyer is an enthusiastic field biologist from Austria.
She recently finished her Master’s degree in Zoology at the University of Vienna, under the direction of Dr. Sabine Tebbich.