Quantifying the Relationship Between Vegetation Characteristics and Avian Diversity in Costa Rica

Abstract

Deforestation and extreme weather events such as wildfires, floods, and droughts fueled by climate change are causing habitat destruction, posing a severe threat to bird populations worldwide. Currently, over 49% of bird species are in decline, necessitating effective and scalable conservation strategies. This study explores the relationship between vegetation characteristics and bird species diversity, using Costa Rica as a case study. By utilizing satellite-based imagery to assess vegetation health, structure, and texture, along with the novel citizen science dataset eBird to catalog bird species richness and diversity, this work overcomes limitations of scale and cost seen in prior studies. Vegetation indices and bird diversity data were derived for 10km x 10km grid cells over forested areas from 2017 to 2023, followed by an analysis of their association. Results indicate a strong correlation between Normalized Difference Vegetation Index (NDVI), a measure of vegetation health, and both bird species richness and diversity, with NDVI’s spatial mean being the best predictor. Kernel NDVI (kNDVI), a non-linear measure of NDVI, and Enhanced Vegetation Index (EVI), another measure of vegetation health, both emerged as the second-best predictor of both bird species richness and diversity. Additionally, bird species richness was more closely associated with vegetation characteristics than species diversity. Bird species richness proved a more robust diversity measure than diversity derived from observation counts. These findings highlight the importance of vegetation health for bird conservation and can guide targeted conservation efforts and policy decisions.