LB 19-198 - Bird Use of Avocado Farms and Intact Forest in the Dominican Republic

Background/Question/Methods:

As the second-largest exporter of avocados worldwide, the Dominican Republic is seeing an increase of avocado farms and a subsequent forest loss. The island of Hispaniola is considered a conservation priority because of its high rates of bird endemism and also serves as an important overwintering ground for Neotropical migrants. Research has shown that agricultural lands, such as shade grown coffee and cacao can provide viable habitat for birds displaced from forests, but avocado farms have not been studied for this purpose. We conducted point-count bird surveys from October-December 2021 in two avocado farm sites and two forest sites, at a total of 102 survey points with three visits to each. We characterized vegetation structure at the same points by taking measurements of canopy cover, upper canopy height, vegetation thickness, and plant species dominance. We used these methods to determine how avian species richness and diversity differ between avocado farms and intact forest, as well as how vegetation differences between farms and forests could impact bird use. We examined our data by looking at bird species overall, and then separately for Neotropical migrant and endemic bird species.

Results/Conclusions:

We found that vegetation structure varied significantly between farm and forest sites, but that overall bird diversity and migrant diversity did not differ between site types. However, we found that endemic bird species showed higher species richness and diversity in intact forest than in avocado farm sites and were also influenced by vegetation characteristics such as canopy cover, upper canopy height, vegetation thickness, and plant species dominance. Our results point to the specific habitat requirements of many of Hispaniolan endemic birds, demonstrating the importance of the protection of native dry forest in the region. Migrant birds had less species richness and diversity in the small farm compared to forest sites and the larger farm, eluding to site selection preferences based on other factors than vegetation structure. We conclude that avocado farms provide habitat for generalist bird species, some migrant species, and very few endemic species that can be considered forest-dependent. We also discuss the potential impacts of farm characteristics and practices affecting farmland habitat value for bird species.