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Ramos, Eric Angel; Maust-Mol, Maria; Collom, Kristi A.; Brady, Beth; Gerstein, Edmund R.; Magnasco, Marcelo O.; Reiss, Diana
(detail)
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2020 |
The Antillean manatee produces broadband vocalizations with ultrasonic frequencies.
Journal of the Acoustical Society of America 147(2): EL80-EL86. 1 tab. 3 figs. doi.org/10.1121/10.0000602 Feb. 5, 2020.
–ABSTRACT: Antillean manatees produce vocalizations reported to be important for communication, but their vocal behavior throughout their geographic range is poorly understood. A SoundTrap recorder (sample rates: 288/576?kHz) was deployed in Belize to record vocalizations of wild manatees in a seagrass channel and of a young rehabilitated and released manatee in a shallow lagoon. Spectral analysis revealed broadband vocalizations with frequencies up to 150?kHz and a high proportion of calls with ultrasonic components. Ultrasonic frequency components appear prevalent in their vocal repertoire and may be important to manatee communication.
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Brady, Beth; Moore, Jon; Love, Kim
(detail)
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2021 |
Behavior related vocalizations of the Florida manatee (Trichechus manatus latirostris).
Mar. Mamm. Sci. https://doi.org/10.1111/mms.12904 Publ. online Dec. 31, 2021.
–ABSTRACT: Florida manatees (Trichechus manatus) produce five broadly defined call types (squeaks, squeals, high squeaks, chirps, squeak-squeals) but their use in social and nonsocial settings is unclear. The goal of this study was to investigate whether call categories and structure of manatee vocalizations varied with behavior. Multiple hydrophones were used to record vocalizations in four different environments and broad behavioral states. Vocalizations recorded from resting, cavorting, stressed, or feeding wild animals were subjected to mixed linear effects models to test whether vocalizations produced varied with behavior and calf presence. Measures of duration, entropy, and frequency modulation were extracted from vocalizations to investigate if structural parameters differ among behaviors. Although all five call categories were recorded, results suggest manatees vocalize using primarily three call types and vary the structure of the call based on behavior. High squeaks were correlated with calf presence. High entropy squeals were proportionally higher during cavorting suggesting they may be related to a heightened state of arousal. Squeaks were the dominant call type produced and were longer in duration and higher in frequency modulation when animals were stressed. This research provides a foundation for comparative studies on vocal behavior for the Florida manatee as well as studies on related species.
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Tennant, Rachel; Brady, Beth; Love, Kim; Ramos, Eric; Schloesser, Ryan
(detail)
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2024 |
Persistent long-term habitat use by Florida manatees at Fort Pierce, Florida from 1997 to 2020.
PlosOne https://doi.org/10.1371/journal.pone.0297636. 7 tabs. 5 figs. Mar. 21, 2024.
–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.
--Review: Ryan Schloesser, Aquatic Mammals, 2004.
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Brady, Beth A. , Eric A. Ramos, Jake A. Lasala, Zoe Nadine R. Ferrell, Nicholas A. Kaney, Emerson Martinez, Maria Renee Areolla Illescas, Joe Arena
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2025 |
Marine Mammal Science Vol. 41, No. 4. June 13, 2025.
–ABSTRACT -- Manatees exhibit diverse vocalizations in various behavioral contexts, but the exact role of these sounds, particularly in terms of sex-based distinctions, remains elusive. This study sought to discern the behavioral and vocal responses of two subspecies of captive West Indian manatees ( Trichechus manatus ) to different call types (squeaks and squeals) to determine whether differences are related to the sex of the signaler. In Mexico, four female Antillean manatees ( Trichechus manatus manatus ) were subjected to playbacks, while in Florida, two male Florida manatees ( Trichechus manatus latirostris ) were used for a parallel experiment. Vocal responses were captured using two hydrophones, with an underwater speaker system facilitating the playback. Video footage was collected to observe behavioral changes in response to playback. Results indicated that neither male nor female manatees increased the number of calls, changed call type, or altered acoustic parameters regardless of call type or whether the sound played was male or female. Likewise, neither males nor females significantly altered their behavior or movement towards the speaker in response to male or female calls, or call type. However, individual Antillean manatees exhibited variation in their behavioral responses to playback of conspecific vocalizations. The results suggest that manatees may not distinguish between the sex of callers.
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Bibliography and Index of the Sirenia and Desmostylia 