Discipline: Ecology Environmental and Earth Sciences
Josefa Munoz - University of Guam
Co-Author(s): Esther Sebastián-González and Patrick J. Hart, University of Hawaii at Hilo
Habitat fragmentation caused by the impeding presence of human land use has led to a decrease in forest habitat ultimately leading to a reduction in biodiversity and species richness. Habitat fragmentation may challenge the acoustic behavior of animals, specifically the acoustic vocalizations produced by birds. This study uses the relatively new bioacoustics techniques to measure bird species richness in forest fragments in southern Costa Rica. We examined if bird species richness was related to the degree of fragmentation (i.e., fragment size, isolation). Bird vocalizations were passively recorded using automatic sound recorders that were placed in six fragments of sizes ranging from 5 to 350 ha. We examined the spectrograms from 80 min of recordings per fragment and classified the different vocalizations based on frequency, shape, and overall sound. The number of different bird vocalizations was counted and used as a proxy for bird species richness and aerial photographs were used to estimate the size of the fragments. We found that large fragments possessed the highest value of bird species richness while small fragments were the least species rich. Also, the number of vocalizations was not related to the amount of habitat surrounding each fragment. Our results demonstrate that in order to increase bird species richness, an increase in fragment size will be beneficial. Use of bioacoustics for measuring bird species richness is a promising, less invasive method that has the potential to provide more information on bird community composition, and can be used for conservation biologists and managers. We hope to improve our understanding of the effect of fragmentation on bird community composition by increasing the amount of recording spots within fragments, sampling additional fragments, and identifying bird species that may improve sound analysis.
Funder Acknowledgement(s): National Science Foundation via the Organization for Tropical Studies.
Faculty Advisor: Sebastián-González, firstname.lastname@example.org
Role: Under the guidance and support of my mentors, E. Sebastián-González and P.J. Hart, I conducted an independent research project. In their company, I distributed and retrieved the automatic sound recorders in the various fragments. I counted and classified the vocalizations in all 96 sound segments. Yerlyn Blanco, the Las Cruces Biological Station GIS laboratory manager, provided the aerial photographs and GIS for the forest fragment information. My mentors aided me as I conducted the statistical analysis of my data and as I completed the manuscript for my research project.