Open Collections

Abstract

Agricultural intensification and expansion are major drivers of global biodiversity loss. Yet, agricultural landscapes also offer important opportunities for conservation. Effective conservation strategies require understanding human-nature relationships, which involves three key players: the landscape, its species, and the people. In this dissertation, I use an interdisciplinary approach, drawing from applied, evolutionary, and molecular ecology as well as social sciences, to examine interactions among landbirds, farmers, and the agricultural landscape on Santa Cruz Island, Galapagos. In Chapter 2, I use an evolutionary ecological framework to investigate whether the agricultural landscape affects the morphology of five Darwin’s finch species. Analyzing beak measurements from 2,085 finches across 17 sites with varying amounts of vegetation at both local and landscape levels, I find that birds have smaller beaks in agricultural compared to natural sites. I discuss possible mechanisms, including adaptive divergence and habitat choice, and contribute to a growing body of evidence that agriculture can shape bird morphology. In Chapter 3, I use a molecular ecology approach to determine whether Galapagos landbirds may be providing arthropod-mediated ecosystem services (pest control) and disservices (consumption of arthropod natural enemies) to farmers. Using the same sampling scheme as Chapter 2, I collected fecal samples (n=750) from 14 bird species and used metabarcoding to analyze their diets. I find that Galapagos landbirds likely eat more pests than natural enemies, although diets vary with land use type, bird species, and season. These results suggest that Galapagos landbirds may help control arthropod pests in the agricultural landscape. In Chapter 4, I use mixed-methods and a social-ecological framework to examine farmers’ perceptions of landbirds, perceived ecosystem services and disservices, and willingness to plant native trees, a key landbird conservation action. From 53 interviews, I find that native landbirds are valued for their cultural ecosystem services, with some differences between species. I also find that farmers are generally willing to plant native trees on their farms, although most in small quantities. Based on the findings, I provide recommendations for Galapagos landbird conservation. Finally, I conclude by comparing findings between chapters and offering recommendations on future research directions and Galapagos landbird conservation.