Cited by 45Avian ecology and behaviorWildlife Ecology and ConservationAnimal Vocal Communication and Behavior

Acoustic indices applied to biodiversity monitoring in a Costa Rica dry tropical forest

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Retamosa Izaguirre, Mónica I., Ramírez-Alán, Oscar·2018·Journal of Ecoacoustics

Abstract

Standardized methods for biodiversity monitoring are needed to evaluate conservation efforts. Acoustic indices are used in biodiversity assessments, but need to be compared to traditional wildlife methods. This work was conducted in the Santa Rosa National Park between June and November, 2015. We installed recorders and conducted bird point counts in twelve sampling sites. We compared acoustic indices (Acoustic Evenness Index [AEI], Acoustic Diversity Index [ADI], Acoustic Complexity Index [ACI], Bioacoustic Index [BIO], Normalized Difference Soundscape Index [NDSI], Total Entropy [TE], Median Amplitude Envelope [MAE], Number of peaks [NP]) with indices from bird point counts (Bird Abundance, Bird Richness, Bird Diversity and Bird Evenness), and discuss the utility of acoustic indices as indicators for biodiversity monitoring in tropical forests. ADI, ACI, BIO and TE presented a similar temporal pattern peaking between 5 am and 6 am; and an additional peak at 5 pm, except for ACI. These patterns were consistent with the daily biological rhythms. AEI, ACI, BIO and Bird Abundance were related to characteristics of younger forests (lower percentage of canopy cover) but NP, ADI, TE, Bird Diversity and Bird Evenness were related to characteristics of older forests (higher percentage of canopy cover and a lower number of patches). ACI was positively correlated to Bird Abundance and NP was positively correlated to Bird Diversity. ACI reflects biological activity, but not necessarily a more diverse bird community in this study area. This might be an indication of a strong acoustic competition, or several highly dominant bird species in younger forests. Furthermore, acoustic communities in tropical forests commonly include insects (cicadas) and frogs, which might affect resulting acoustic indices. A variety of methods are probably needed to thoroughly assess biodiversity. However, a combination of indices such as ACI and NP might be considered to monitor trends in abundance and diversity of birds in dry forests.

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  • Spectral and temporal entropy quantify how ordered a soundscape is, giving clues about community evenness or ecological stress.

    “Measures like spectral and temporal entropy add a different lens, quantifying how ordered a soundscape is, which in turn gives clues about community evenness or ecological stress”

    From Listening forward: emerging roles of bioacoustics in ecology, evolution, and conservation (2026) · cites this paper as Retamosa Izaguirre and Ramírez-Alán 2018

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  9. Retamosa Izaguirre et al. | Acoustics indices and biodiversity in tropical forests https://www.veruscript.com/a/TNW2NP/ J. Ecoacoust. | 2018 | 2: #TNW2NP | https://doi.org/10.22261/JEA. · DOI
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Authors
Retamosa Izaguirre, M. I., & Ramírez-Alán, O.
Venue
Journal of Ecoacoustics
Publisher
MDPI AG
Published
2018-04-26
Volume
2
Issue
1
Pages
1-1
ISSN
2516-1466 (ISSN-L)
OpenAlex
W2803020503
Cited by
45
References
58
Citations by year
2026: 6 · 2025: 4 · 2024: 4 · 2023: 9 · 2022: 5 · 2021: 7 · 2020: 6 · 2019: 3 · 2018: 1
FWCI
3.20
Type
journal article
Language
en
Open access
Locations
Journal of Ecoacoustics (publishedVersion, cc-by)
Funders
Universidad Nacional, Costa Rica.
Topics
  • Physical Sciences › Environmental Science › Ecology › Avian ecology and behavior
  • Physical Sciences › Environmental Science › Ecology › Wildlife Ecology and Conservation
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Developmental Biology › Animal Vocal Communication and Behavior
Keywords
acoustic indices, biodiversity monitoring, bird diversity, bird abundance, tropical dry forest, Santa Rosa National Park, canopy cover, stand age, soundscape, acoustic competition, diel activity patterns, acoustic complexity index, total entropy

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