Can we use acoustic indices to estimate the relative number of bird species in urban areas?

10 Feb 2025

UP Diliman

Birds are used as biological indicators of ecosystem health. They are often surveyed through point count method which requires skilled observers to record all the birds heard and seen in the area. However, this method requires a lot of effort and considerable time, thereby limiting the spatial and temporal coverage of bird surveys.

With the help of technology, studying and monitoring biodiversity can be made easier. Passive acoustic monitoring is gaining popularity and usage across a wide range of ecosystems, asking questions such as how many species are there, how abundant are they, and how do their population change over time or space. By placing cheap sound recorders in the field, we can cover a greater area with less resources than having human observers and can cover longer periods. The challenge with such acoustic surveys, however, is the processing effort required to analyze extensive sound data collections and translate them into biodiversity measures that can give timely information relevant to species conservation and management. Researchers have developed acoustic indices to describe the soundscape features, but their use are often context dependent.

In this study, we asked the question, “Can we use acoustic indices to estimate the relative number of bird species in urban areas?” We recorded the soundscape at three locations in UP Diliman, and we computed the eight acoustic indices from a sample of 5-min sound clips. For each clip, we manually listened and recorded all the birds heard (also called species richness). We then compared the acoustic indices with the obtained species richness. We found that the acoustic indices used in the study were not highly correlated to actual bird species richness. The noise from the people and the weather may have affected the indices, so we recommend pre-processing the sound clips and conducting ground-truthing before applying the indices.

Authors: Skyla Dennise U. Diaz (Institute of Biology, College of Science, University of the Philippines Diliman) , Jelaine L. Gan (Institute of Biology, College of Science, University of the Philippines Diliman) and Giovanni A. Tapang ( National Institute of Physics, College of Science, University of the Philippines Diliman)

Read the full paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0289001

Can we use acoustic indices to estimate the relative number of bird species in urban areas?

Birds are used as biological indicators of ecosystem health. They are often surveyed through point count method which requires skilled observers to record all the birds heard and seen in the area. However, this method requires a lot of effort and considerable time, thereby limiting the spatial and temporal coverage of bird surveys.

With the help of technology, studying and monitoring biodiversity can be made easier. Passive acoustic monitoring is gaining popularity and usage across a wide range of ecosystems, asking questions such as how many species are there, how abundant are they, and how do their population change over time or space. By placing cheap sound recorders in the field, we can cover a greater area with less resources than having human observers and can cover longer periods. The challenge with such acoustic surveys, however, is the processing effort required to analyze extensive sound data collections and translate them into biodiversity measures that can give timely information relevant to species conservation and management. Researchers have developed acoustic indices to describe the soundscape features, but their use are often context dependent.

In this study, we asked the question, “Can we use acoustic indices to estimate the relative number of bird species in urban areas?” We recorded the soundscape at three locations in UP Diliman, and we computed the eight acoustic indices from a sample of 5-min sound clips. For each clip, we manually listened and recorded all the birds heard (also called species richness). We then compared the acoustic indices with the obtained species richness. We found that the acoustic indices used in the study were not highly correlated to actual bird species richness. The noise from the people and the weather may have affected the indices, so we recommend pre-processing the sound clips and conducting ground-truthing before applying the indices.

Authors: Skyla Dennise U. Diaz (Institute of Biology, College of Science, University of the Philippines Diliman) , Jelaine L. Gan (Institute of Biology, College of Science, University of the Philippines Diliman) and Giovanni A. Tapang ( National Institute of Physics, College of Science, University of the Philippines Diliman)

Read the full paper: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0289001