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Erb WM, Ross W, Kazanecki H, Mitra Setia T, Madhusudhana S, Clink DJ. Vocal complexity in the long calls of Bornean orangutans. PeerJ 2024; 12:e17320. [PMID: 38766489 PMCID: PMC11100477 DOI: 10.7717/peerj.17320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 04/09/2024] [Indexed: 05/22/2024] Open
Abstract
Vocal complexity is central to many evolutionary hypotheses about animal communication. Yet, quantifying and comparing complexity remains a challenge, particularly when vocal types are highly graded. Male Bornean orangutans (Pongo pygmaeus wurmbii) produce complex and variable "long call" vocalizations comprising multiple sound types that vary within and among individuals. Previous studies described six distinct call (or pulse) types within these complex vocalizations, but none quantified their discreteness or the ability of human observers to reliably classify them. We studied the long calls of 13 individuals to: (1) evaluate and quantify the reliability of audio-visual classification by three well-trained observers, (2) distinguish among call types using supervised classification and unsupervised clustering, and (3) compare the performance of different feature sets. Using 46 acoustic features, we used machine learning (i.e., support vector machines, affinity propagation, and fuzzy c-means) to identify call types and assess their discreteness. We additionally used Uniform Manifold Approximation and Projection (UMAP) to visualize the separation of pulses using both extracted features and spectrogram representations. Supervised approaches showed low inter-observer reliability and poor classification accuracy, indicating that pulse types were not discrete. We propose an updated pulse classification approach that is highly reproducible across observers and exhibits strong classification accuracy using support vector machines. Although the low number of call types suggests long calls are fairly simple, the continuous gradation of sounds seems to greatly boost the complexity of this system. This work responds to calls for more quantitative research to define call types and quantify gradedness in animal vocal systems and highlights the need for a more comprehensive framework for studying vocal complexity vis-à-vis graded repertoires.
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Affiliation(s)
- Wendy M. Erb
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, United States of America
- Department of Anthropology, Rutgers, The State University of New Jersey, New Brunswick, United States of America
| | - Whitney Ross
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, United States of America
| | - Haley Kazanecki
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, United States of America
| | - Tatang Mitra Setia
- Primate Research Center, Universitas Nasional Jakarta, Jakarta, Indonesia
- Department of Biology, Faculty of Biology and Agriculture, Universitas Nasional Jakarta, Jakarta, Indonesia
| | - Shyam Madhusudhana
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, United States of America
- Centre for Marine Science and Technology, Curtin University, Perth, Australia
| | - Dena J. Clink
- K. Lisa Yang Center for Conservation Bioacoustics, Cornell Lab of Ornithology, Cornell University, Ithaca, NY, United States of America
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Tennant R, Brady B, Love K, Ramos E, Schloesser R. Persistent long-term habitat use by Florida manatees at Fort Pierce, Florida from 1997 to 2020. PLoS One 2024; 19:e0297636. [PMID: 38512843 PMCID: PMC10956764 DOI: 10.1371/journal.pone.0297636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 11/28/2023] [Indexed: 03/23/2024] Open
Abstract
To survive cold winters, Florida manatees (Trichechus manatus latirostris) depend on artificial (i.e., power plants) and natural warm water sources such as springs and passive thermal basins. Passive thermal basins can provide critical habitat for manatees for short or extended periods of time. The Henry D. King Powerplant in Fort Pierce, Florida discharged warm water into Moore's Creek until it went offline in 1995. However, it is unknown to what degree manatees continue to occupy this area and how environmental factors influence their occurrence in the creek. To explore this, we examined the habitat use of Florida manatees in Moore's Creek after the shutdown from November 1997 to March 2020 from daily counts of manatees. In addition, we correlated local environmental data (ambient air, temperature, salinity) to assess if Moore's Creek had properties indicative of a passive thermal basin. Results indicated there was not an increase or decrease in habitat use over twenty years in the Creek. The consistent use of Moore's Creek over the study period suggests that this habitat possesses thermal and freshwater resources to support manatee occurrence long-term. These findings provide robust support for the importance of this habitat and passive thermal basins for Florida manatees.
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Affiliation(s)
- Rachel Tennant
- Manatee Observation and Education Center, Fort Pierce, Florida, United States of America
| | - Beth Brady
- Mote Marine Laboratory, Sarasota, Florida, United States of America
| | - Kim Love
- K. R. Love Quantitative Consulting and Collaboration, Athens, Georgia, United States of America
| | - Eric Ramos
- Fundación Internacional para la Naturaleza y la Sustentabilidad, Chetumal, Quintana Roo, México
- University of Vermont, Burlington, Vermont, United States of America
| | - Ryan Schloesser
- Mote Marine Laboratory, Sarasota, Florida, United States of America
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3
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Díaz S, Labra A. Exploring Sound Emission of the Lizard Pristidactylus valeriae. Animals (Basel) 2023; 13:3813. [PMID: 38136850 PMCID: PMC10740820 DOI: 10.3390/ani13243813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Revised: 12/03/2023] [Accepted: 12/08/2023] [Indexed: 12/24/2023] Open
Abstract
Lizards, except geckos, are generally considered voiceless organisms, although some species emit oral sounds. For most of these "vocal lizards", however, there is almost no information on the characteristics of the sounds, precluding exploration of the functionality and evolution of the sounds. Pristidactylus are known as "grunter lizards" since individuals emit oral sounds under predation risk. We explored the characteristics of the sounds emitted by P. valeriae, recording 17 adults and 1 juvenile when they were threatened and captured by a predator. Only adults emitted sounds with open mouths and displayed aggressive postures, e.g., biting attempts. These sounds correspond to hisses, which lack amplitude or frequency modulation. The lizards emitted longer hisses when threatened than when captured by the predator, which may provide honest information on individuals' ability to escape. In addition, males may experience higher distress during threats since their hisses had higher aggregate entropy than those of the females. Finally, hissing has been documented in four of the five Leiosauridae genera, the family to which Pristidactylus belongs, suggesting that sound emission is ancestral to the family.
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Affiliation(s)
- Sebastián Díaz
- Laboratorio de Ecología Geográfica, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile;
| | - Antonieta Labra
- Center for Ecological and Evolutionary Synthesis (CEES), Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, NO-0316 Oslo, Norway
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4
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Brady B, Sarbacker C, Lasala JA, Maust-Mohl M, Collom KA, Searle L, May-Collado LJ, Ramos EA. Manatees display diel trends in acoustic activity at two microhabitats in Belize. PLoS One 2023; 18:e0294600. [PMID: 37976271 PMCID: PMC10655963 DOI: 10.1371/journal.pone.0294600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 11/03/2023] [Indexed: 11/19/2023] Open
Abstract
Many marine mammals exhibit diel trends in vocal production, which can provide information on habitat use and behavioral activity. In Belize, Antillean manatees (Trichechus manatus manatus) commonly inhabit small depressions in the substrate or deep-water coves known as "resting holes". Determining if manatees exhibit diel temporal trends in their call production rate and call types between microhabitats can provide insights into their diurnal and nocturnal activity patterns. Here, we investigate the diel vocalization patterns of wild Antillean manatees in two adjacent resting holes off of St. George's Caye, Belize. Recordings of manatees were made using a bottom-mounted hydrophone located near a reef barrier reef for nine days in July of 2017 and ten days in January of 2018. To explore if and how manatee acoustic activity differs between sites, we compared the number of calls per hour, the number of manatee positive hours, the number of tonal and atonal sounds, and the number of boats detected across sites. A total of 370 hours of acoustic recordings were analyzed resulting in the detection of 3,262 calls. There were no significant differences in the number of manatee calls produced per hour between sites. The average number of calls produced by manatees decreased over the course of several days. The proportion of tonal calls decreased with hours after sunset and increased in boat presence. These results suggest manatees in this region may exhibit different diel activity patterns which appear to be influenced by the characteristics of the environment. These findings can support ongoing conservation and management efforts to safeguard species in Belize.
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Affiliation(s)
- Beth Brady
- Mote Marine Laboratory, Sarasota, Florida, United States of America
| | - Carly Sarbacker
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
| | | | - Maria Maust-Mohl
- Department of Psychology, Manhattan College, Riverdale, New York, United States of America
| | - Kristi Ashley Collom
- Department of Psychology, Hunter College, City University of New York, New York, New York, United States of America
| | | | - Laura J. May-Collado
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
- Smithsonian Tropical Research Institute Apartado Postal 0843–03092 Panamá, Panama, República de Panamá
| | - Eric Angel Ramos
- Department of Biology, University of Vermont, Burlington, Vermont, United States of America
- Fundación Internacional para la Naturaleza y la Sustentabilidad (FINS), Chetumal, Quintana Roo, México
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5
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Brewer AM, Castellote M, Van Cise AM, Gage T, Berdahl AM. Communication in Cook Inlet beluga whales: Describing the vocal repertoire and masking of calls by commercial ship noise. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2023; 154:3487-3505. [PMID: 38032263 DOI: 10.1121/10.0022516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 11/06/2023] [Indexed: 12/01/2023]
Abstract
Many species rely on acoustic communication to coordinate activities and communicate to conspecifics. Cataloging vocal behavior is a first step towards understanding how individuals communicate information and how communication may be degraded by anthropogenic noise. The Cook Inlet beluga population is endangered with an estimated 331 individuals. Anthropogenic noise is considered a threat for this population and can negatively impact communication. To characterize this population's vocal behavior, vocalizations were measured and classified into three categories: whistles (n = 1264, 77%), pulsed calls (n = 354, 22%), and combined calls (n = 15, 1%), resulting in 41 call types. Two quantitative analyses were conducted to compare with the manual classification. A classification and regression tree and Random Forest had a 95% and 85% agreement with the manual classification, respectively. The most common call types per category were then used to investigate masking by commercial ship noise. Results indicate that these call types were partially masked by distant ship noise and completely masked by close ship noise in the frequency range of 0-12 kHz. Understanding vocal behavior and the effects of masking in Cook Inlet belugas provides important information supporting the management of this endangered population.
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Affiliation(s)
- Arial M Brewer
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Manuel Castellote
- Cooperative Institute for Climate, Ocean and Ecosystem Studies, University of Washington, Seattle, Washington 98195, USA
| | - Amy M Van Cise
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA
| | - Tom Gage
- Alaska Department of Fish and Game, Anchorage, Alaska 99518, USA
| | - Andrew M Berdahl
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, Washington 98195, USA
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6
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Henaut Y, Delfour F. Manatees in Zoological Parks throughout the World: History, State, and Welfare. Animals (Basel) 2023; 13:3228. [PMID: 37893952 PMCID: PMC10603729 DOI: 10.3390/ani13203228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/10/2023] [Accepted: 10/12/2023] [Indexed: 10/29/2023] Open
Abstract
The order Sirenia comprises several species of manatees and one species of dugong. These popular marine mammals are relatively recent acquisitions to zoological parks throughout the world. As far as we know, there are less than 200 manatees, mostly American, a few African, and ever less Amazonian, currently in zoological parks. American manatees are predominantly found in zoos in Europe, North America, and in some Asian countries, while African ones are present exclusively in Asian zoos. The living conditions of captive manatees differ considerably from zoo to zoo (i.e., numbers, sex ratio, outdoor vs. indoor habitats, complex vs. simple habitats). Most research on manatee behaviour has been relatively recent, and studies on cognition, sociality, and ecology have a significant impact on our perception of manatee needs and management, with wider implications for their welfare. In the wild, manatees demonstrated various cognitive capacities; spatial memory and learning abilities play an important role in their daily life in a complex and dynamic environment. Furthermore, there is evidence that these mammals are more social animals than expected. Individuals show various personality traits on the boldness-shyness continuum and their sociality varies. All those parameters are important in terms of animal welfare. Several behavioural studies showed that standardized enrichment programs benefit and ensure the welfare of captive zoo animals. However, obtaining accurate information on the presence of manatees in zoos, living conditions, management, and consequently welfare remains challenging. This study examines the current knowledge on manatee behaviour and cognition and then discusses different approaches to improving the welfare of this charismatic marine mammal in zoological parks.
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Affiliation(s)
- Yann Henaut
- Laboratorio de Conducta Animal, Grupo Académico Interacción, Adaptación y Biodiversidad, El Colegio de la Frontera Sur (ECOSUR), Chetumal 77014, Quintana Roo, Mexico
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7
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Reyes-Arias JD, Brady B, Ramos EA, Henaut Y, Castelblanco-Martínez DN, Maust-Mohl M, Searle L, Pérez-Lachaud G, Guzmán HM, Poveda H, Merchan F, Contreras K, Sanchez-Galan JE, Collom KA, Magnasco MO. Vocalizations of wild West Indian manatee vary across subspecies and geographic location. Sci Rep 2023; 13:11028. [PMID: 37419931 PMCID: PMC10328939 DOI: 10.1038/s41598-023-37882-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 06/29/2023] [Indexed: 07/09/2023] Open
Abstract
Geographic variation in the vocal behavior of manatees has been reported but is largely unexplored. Vocalizations of wild West Indian manatees (Trichechus manatus) were recorded with hydrophones in Florida from Florida manatees (Trichechus manatus latirostris), and in Belize and Panama from Antillean manatees (Trichechus manatus manatus) to determine if calls varied between subspecies and geographic regions. Calls were visually classified into five categories: squeaks, high squeaks, squeals, squeak-squeals, and chirps. From these five categories, only three call types (squeaks, high squeaks and squeals) were observed in all three populations. Six parameters from the temporal and frequency domains were measured from the fundamental frequency of 2878 manatee vocalizations. A repeated measures PERMANOVA found significant differences for squeaks and high squeaks between each geographic location and for squeals between Belize and Florida. Almost all measured frequency and temporal parameters of manatee vocalizations differed between and within subspecies. Variables that may have influenced the variation observed may be related to sex, body size, habitat and/or other factors. Our findings provide critical information of manatee calls for wildlife monitoring and highlight the need for further study of the vocal behavior of manatees throughout their range.
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Affiliation(s)
- Jessica D Reyes-Arias
- Conservación de la Biodiversidad, El Colegio de la Frontera Sur, 77014, Chetumal, Quintana Roo, Mexico
| | - Beth Brady
- Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, FL, 34236, USA
| | - Eric A Ramos
- Fundación Internacional para la Naturaleza y la Sustentabilidad (FINS), 77014, Chetumal, Quintana Roo, Mexico
- The Rockefeller University, 1230 York Ave., New York, NY, 10065, USA
| | - Yann Henaut
- Conservación de la Biodiversidad, El Colegio de la Frontera Sur, 77014, Chetumal, Quintana Roo, Mexico.
| | - Delma Nataly Castelblanco-Martínez
- Fundación Internacional para la Naturaleza y la Sustentabilidad (FINS), 77014, Chetumal, Quintana Roo, Mexico.
- Universidad Autónoma del Estado de Quintana Roo, 77039, Chetumal, Quintana Roo, Mexico.
- Consejo Nacional de Ciencia y Tecnología, 03940, Ciudad de México, Mexico.
| | - Maria Maust-Mohl
- Department of Psychology, Manhattan College, Riverdale, New York, NY, 10471, USA
| | | | - Gabriela Pérez-Lachaud
- Conservación de la Biodiversidad, El Colegio de la Frontera Sur, 77014, Chetumal, Quintana Roo, Mexico
| | - Héctor M Guzmán
- Smithsonian Tropical Research Institute, 0843-03092, Panama City, Panama
| | - Héctor Poveda
- Grupo de Investigación en Sistemas de Comunicaciones Digitales Avanzados (GISCDA), Facultad de Ingeniería de Eléctrica, Universidad Tecnológica de Panamá, El Dorado, Panama City, 0819-07289, Panama
| | - Fernando Merchan
- Grupo de Investigación en Sistemas de Comunicaciones Digitales Avanzados (GISCDA), Facultad de Ingeniería de Eléctrica, Universidad Tecnológica de Panamá, El Dorado, Panama City, 0819-07289, Panama
| | - Kenji Contreras
- Grupo de Investigación en Sistemas de Comunicaciones Digitales Avanzados (GISCDA), Facultad de Ingeniería de Eléctrica, Universidad Tecnológica de Panamá, El Dorado, Panama City, 0819-07289, Panama
| | - Javier E Sanchez-Galan
- Facultad de Ingeniería de Sistemas Computacionales, Universidad Tecnologica de Panama, Campus Victor Levi Sasso, Panama, Panama
| | - Kristi A Collom
- Department of Psychology, Hunter College, City University of New York, New York, NY, 10065, USA
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Umeed R, Lucchini K, Santos PJ, Attademo F, Luna F, Normande I, Bezerra B. Vocal complexity in Antillean manatees (Trichechus manatus manatus). BEHAVIOUR 2022. [DOI: 10.1163/1568539x-bja10199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Abstract
Vocal complexity can be expressed through variations in repertoire size, structure, and individual manatee repertoires. Here we aimed to assess the complexity of the vocal behaviour of Antillean manatees living in captivity (i.e., artificial pools) and in reintroduction enclosures (i.e., natural enclosures placed in an estuarine area). Specifically, we evaluated: (i) the structure of vocalisations to assess whether they had variants; (ii) the variation in call production (rate and pattern) between groups with different configurations; (iii) whether individuality occurred in vocalisation structure. We found four categories of vocalisations, of which two had different variants. Not all study groups produced all call categories and variants. Older and younger males in the reintroduction enclosures had the highest call rates compared to captive females and captive males. The vocal and behavioural patterns differed between groups. Squeak call structure differed between individuals. Such vocal complexity may aid manatees in adapting to their dynamic social and structural environment, facilitating communication.
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Affiliation(s)
- Rebecca Umeed
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Karen Lucchini
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Pernambuco, Brazil
- Instituto Chico Mendes de Conservação da Biodiversidade/Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos (ICMBio/CMA), Santos, São Paulo, Brazil
| | - Paulo J.P. Santos
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Pernambuco, Brazil
| | - Fernanda Attademo
- Instituto Chico Mendes de Conservação da Biodiversidade/Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos (ICMBio/CMA), Santos, São Paulo, Brazil
| | - Fabia Luna
- Instituto Chico Mendes de Conservação da Biodiversidade/Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos (ICMBio/CMA), Santos, São Paulo, Brazil
| | - Iran Normande
- Instituto Chico Mendes de Conservação da Biodiversidade/Reserva Extrativista Marinha da Lagoa do Jequiá, Jequiá da Praia, Alagoas, Brazil
- Programa de Pós-graduação em Diversidade Biológica e Conservação nos Trópicos, Laboratório de Biologia Marinha e Conservação e Laboratório de Conservação no Século XXI, Universidade Federal de Alagoas, Alagoas, Brasil
| | - Bruna Bezerra
- Programa de Pós-Graduação em Biologia Animal, Departamento de Zoologia, Universidade Federal de Pernambuco, Pernambuco, Brazil
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Rycyk AM, Berchem C, Marques TA. Estimating Florida manatee (Trichechus manatus latirostris) abundance using passive acoustic methods. JASA EXPRESS LETTERS 2022; 2:051202. [PMID: 36154061 DOI: 10.1121/10.0010495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Manatees are difficult to detect, particularly cryptic populations that inhabit areas with limited water clarity. The effectiveness of using vocal detections to estimate manatee abundance was evaluated in a clear water spring where manatees congregate seasonally. Vocalizations were extracted by a detection classifier that clustered sounds with similar spectral properties. Vocalization counts from recordings in Blue Spring, FL, USA were strong predictors of manatee abundance. The link between independent visual counts and abundance estimates from passive acoustic monitoring was used to provide an estimate of 1.059 (95% confidence interval 0.963-1.127) vocalizations/manatee/5-min, which might be used elsewhere for cue counting of manatees.
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Affiliation(s)
- Athena M Rycyk
- Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243, USA
| | - Cora Berchem
- Save the Manatee Club, Maitland Florida 32751, USA
| | - Tiago A Marques
- Centre for Research into Ecological and Environmental Modelling, University of St Andrews, St Andrews, KY16 9LZ, Scotland ; ;
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10
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Rycyk AM, Factheu C, Ramos EA, Brady BA, Kikuchi M, Nations HF, Kapfer K, Hampton CM, Garcia ER, Takoukam Kamla A. First characterization of vocalizations and passive acoustic monitoring of the vulnerable African manatee (Trichechus senegalensis). THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2021; 150:3028. [PMID: 34717514 DOI: 10.1121/10.0006734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 09/24/2021] [Indexed: 06/13/2023]
Abstract
Even among the understudied sirenians, African manatees (Trichechus senegalensis) are a poorly understood, elusive, and vulnerable species that is difficult to detect. We used passive acoustic monitoring in the first effort to acoustically detect African manatees and provide the first characterization of their vocalizations. Within two 3-day periods at Lake Ossa, Cameroon, at least 3367 individual African manatee vocalizations were detected such that most vocalizations were detected in the middle of the night and at dusk. Call characteristics such as fundamental frequency, duration, harmonics, subharmonics, and emphasized band were characterized for 289 high-quality tonal vocalizations with a minimum signal-to-noise ratio of 4.5 dB. African manatee vocalizations have a fundamental frequency of 4.65 ± 0.700 kHz (mean ± SD), duration of 0.181 ± 0.069 s, 97% contained harmonics, 21% contained subharmonics, and 27% had an emphasized band other than the fundamental frequency. Altogether, the structure of African manatee vocalizations is similar to other manatee species. We suggest utilizing passive acoustic monitoring to fill in the gaps in understanding the distribution and biology of African manatees.
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Affiliation(s)
- Athena M Rycyk
- Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243, USA
| | - Clinton Factheu
- Department of Animal Biology and Physiology, University of Yaounde I, Yaoundé, Cameroon
| | - Eric A Ramos
- Fundación Internacional para la Naturaleza y la Sustentabilidad (FINS), Chetumal, Quintana Roo, Mexico
| | - Beth A Brady
- Mote Marine Laboratory, Sarasota, Florida 34236, USA
| | - Mumi Kikuchi
- Japan Manatee Education and Study Lab, Tokyo, JP 1040041, Japan
| | - Hannah F Nations
- Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243, USA
| | - Karianne Kapfer
- Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243, USA
| | - Cecilia M Hampton
- Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243, USA
| | - Emily R Garcia
- Division of Natural Sciences, New College of Florida, Sarasota, Florida 34243, USA
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11
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Erbs F, van der Schaar M, Weissenberger J, Zaugg S, André M. Contribution to unravel variability in bowhead whale songs and better understand its ecological significance. Sci Rep 2021; 11:168. [PMID: 33420221 PMCID: PMC7794550 DOI: 10.1038/s41598-020-80220-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 12/14/2020] [Indexed: 01/29/2023] Open
Abstract
Since the first studies on bowhead whale singing behaviour, song variations have been consistently reported. However, there has been little discussion regarding variability in bowhead whale singing display and its ecological significance. Unlike the better studied humpback whales, bowhead whales do not appear to share songs at population level, but several studies have reported song sharing within clusters of animals. Over the winter season 2013-2014, in an unstudied wintering ground off Northeast Greenland, 13 song groups sharing similar hierarchical structure and units were identified. Unit types were assessed through multidimensional maps, showing well separated clusters corresponding to manually labelled units, and revealing the presence of unit subtypes. Units presented contrasting levels of variability over their acoustic parameters, suggesting that bowhead whales keep consistency in some units while using a continuum in values of frequency, duration and modulation parameters for other unit types. Those findings emphasise the need to account for variability in song analysis to better understand the behavioural ecology of this endangered species. Additionally, shifting from song toward units or phrase-based analysis, as it has been suggested for humpback whales, offers the opportunity to identify and track similarities in songs over temporal and geographical scales relevant to population monitoring.
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Affiliation(s)
- F Erbs
- Laboratory of Applied Bioacoustics, Technical University of Catalonia, BarcelonaTech (UPC), Barcelona, Spain
| | - M van der Schaar
- Laboratory of Applied Bioacoustics, Technical University of Catalonia, BarcelonaTech (UPC), Barcelona, Spain
| | | | - S Zaugg
- Laboratory of Applied Bioacoustics, Technical University of Catalonia, BarcelonaTech (UPC), Barcelona, Spain
| | - M André
- Laboratory of Applied Bioacoustics, Technical University of Catalonia, BarcelonaTech (UPC), Barcelona, Spain.
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12
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Bioacoustic Classification of Antillean Manatee Vocalization Spectrograms Using Deep Convolutional Neural Networks. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10093286] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We evaluated the potential of using convolutional neural networks in classifying spectrograms of Antillean manatee (Trichechus manatus manatus) vocalizations. Spectrograms using binary, linear and logarithmic amplitude formats were considered. Two deep convolutional neural networks (DCNN) architectures were tested: linear (fixed filter size) and pyramidal (incremental filter size). Six experiments were devised for testing the accuracy obtained for each spectrogram representation and architecture combination. Results show that binary spectrograms with both linear and pyramidal architectures with dropout provide a classification rate of 94–99% on the training and 92–98% on the testing set, respectively. The pyramidal network presents a shorter training and inference time. Results from the convolutional neural networks (CNN) are substantially better when compared with a signal processing fast Fourier transform (FFT)-based harmonic search approach in terms of accuracy and F1 Score. Taken together, these results prove the validity of using spectrograms and using DCNNs for manatee vocalization classification. These results can be used to improve future software and hardware implementations for the estimation of the manatee population in Panama.
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