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.
