Differences in distress: Variance and production of American Crocodile (Crocodylus acutus) distress calls in Belize
Open accessAbstract
Acoustic communication of American Crocodiles (Crocodylus acutus) is relatively understudied. Our overall aim was to determine the acoustic structure of wild American Crocodile distress calls, distinguish call differences among size classes (hatchling, juvenile, sub‐adult, and adult), and investigate call production on a gradient of human disturbance. American Crocodile distress calls have strong frequency modulation and are comprised of multiple harmonics in a downsweeping pattern. Measured parameters (total duration, first quartile duration, maximal frequency, first quartile frequency, end frequency, slope of first quartile, slope of last quartiles) differed significantly among size classes (p < .05). Hatchling distress calls are higher in frequency and strongly modulated, whereas calls produced by sub‐adults and adults showed little modulation, are lower in frequency, and have greater overall duration. Proportion of crocodiles that produced distress calls during capture differed by size class and sampling location, particularly adult distress calls which are reported here to be produced with undocumented frequency. We determined that American Crocodiles of all size classes produce distress calls at varying rates among study sites. Our results demonstrate that American crocodiles produce distress call more frequently at sites with higher anthropogenic activity. Measured call parameters of juveniles and hatchling American crocodiles also varied among sites in relation to human disturbance. Calls recorded at sites of high anthropogenic impact have increased duration and less modulation which may adversely affect response to emitted distress calls. Proportional and call parameter variances suggest anthropogenic activity as a driver for increased call production and alteration of call parameters at high human‐impacted sites.
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In other studies, the acoustic parameters of crocodylian acoustic signals are affected by habitat, anthropogenic disturbance and signalling location (air vs. water).
“In other studies, the acoustic parameters of crocodylian acoustic signals are affected by habitat (Dinets 2011, 2013a, 2013b), anthropogenic disturbance (Boucher et al. 2020) and signalling location (air vs. water) (Jensen et al. 2024) indicating the importance of context.”
From Roars, Rumbles, and Resonance: A Systematic Review and Meta‐Analysis of Crocodylian Acoustic Signals (2026) · cites this paper as Boucher et al. 2020
The Abstract reports that distress-call parameters of juvenile and hatchling American crocodiles varied among sites in relation to human disturbance. However, the Discussion (Call production; page unavailable) says further research is needed to determine whether those differences truly reflect anthropogenic impact. The citing sentence states the effect more definitively than the source does; the habitat and air-versus-water portions are attributed to other citations. (LLM, conf=0.88)
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References 24 · Cited by 6
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- Authors
- Boucher, M., Tellez, M., & Anderson, J. T.
- Affiliations
- West Virginia University (US)
- University of California, Santa Barbara (US)
- Corresponding author
- Anderson, James T.
- Venue
- Ecology and Evolution
- Publisher
- Wiley
- Published
- 2020-08-25
- Volume
- 10
- Issue
- 18
- Pages
- 9624-9634
- ISSN
- 2045-7758 (ISSN-L)
- PMC
- PMC7520206
- OpenAlex
- W3080131944
- Cited by
- 6
- References
- 24
- Citations by year
- 2026: 1 · 2024: 3 · 2023: 1 · 2020: 1
- FWCI
- 0.46
- Type
- journal article
- Language
- en
- Open access
- gold
- doi.org
- Locations
- Ecology and Evolution (publishedVersion, cc-by)
- PubMed Central (publishedVersion, cc-by)
- PubMed (publishedVersion)
- DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
- Funders
- National Science Foundation (01A‐1458952)
- National Institute of Food and Agriculture (WVA00117, WVA00812)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Developmental Biology › Animal Vocal Communication and Behavior
- Physical Sciences › Environmental Science › Ecology › Marine animal studies overview
- Physical Sciences › Environmental Science › Global and Planetary Change › Amphibian and Reptile Biology
- Keywords
- American crocodile, Crocodylus acutus, distress calls, acoustic communication, call parameters, human disturbance, anthropogenic impacts, frequency modulation, call duration, Belize
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