Avian Community Assembly Following Volcanic Disturbance at Volcán Arenal, Costa Rica and Mount St. Helens, USA

Abstract

Volcanism is an agent of major disturbance in many parts of the world. While the effects of volcanic disturbance are fairly well-known among some groups of species, few studies have been performed in bird communities. Likewise, few studies have attempted to compare how communities in temperate and tropical biomes respond to volcanism. This study examines how bird communities inhabiting areas recently disturbed by volcanism differ at Mount St. Helens in the United States, and Volcán Arenal in Costa Rica. I compare the two bird communities to evaluate patterns in species richness, species diversity and guild diversity and how those patterns fit with previously described differences in temperate and tropical bird communities. The two communities generally exhibited similarity in richness and diversity, although small sample sizes at Arenal may have influenced ability to detect differences. Nevertheless, my results suggest that the relatively low complexity of vegetation at these early successional study sites may explain the greater similarity than initially predicted. My results also suggest the greatest difference between the temperate and tropical sites is in the most structurally complex sites. Additional surveys at these and other sites are needed to reveal the generality of my results.