Manatee Vocal Behavior

African Manatees

Deployment of a passive acoustic recorder in Lake Ossa, Cameroon (photo credit: Clinton Factheu, MSc. and current PhD Student at University of Yaoundé I).

African manatees (Trichechus senegalensis) are elusive and face many threats throughout their range in over 21 countries in Africa. They are the least studied manatee species, and this includes their acoustics. Through a collaboration with the African Marine Mammal Conservation Organization founded and led by Dr. Aristide Takoukam Kamla we have recorded African manatees in the wild using passive acoustics! These recordings are forming the basis of the first description of their vocalizations in the scientific literature. We hope in the future to use passive detection of their vocalizations to learn more about their ecology (read more here or listen to this podcast).

Recent work in this area

Factheu, C., Rycyk, A. M., Kekeunou, S., Keith-Diagne, L. W., Ramos, E. A., Kikuchi, M., & Takoukam Kamla, A. (2023). Acoustic methods improve the detection of the endangered African manatee. Frontiers in Marine Science, 9, 1032464. https://doi.org/10.3389/fmars.2022.1032464

Rycyk, Athena , Factheu, Clinton, Ramos, Eric, Brady, Beth, Kikuchi, Mumi, Nations, Hannah, Kapfer, Karianne, Hampton, Cecilia, Garcia, Emily, & Takoukam Kamla, Aristide (2021). First characterization of vocalizations and passive acoustic monitoring of the vulnerable African manatee (Trichechus senegalensis), Journal of the Acoustical Society of America, 150: 3028-3037, https://doi.org/10.1121/10.0006734

Student authors are underlined

Detecting African manatee vocalizations has become a whole lot easier with the development of a convolutional neural network! We combined recordings from Cameroon (African Marine Mammal Conservation Organization) and Nigeria (Nigerian Institute for Oceanography and Marine Research) to develop this automated method of extracting African manatee vocalizations. This work was featured on the cover of JASA Express Letters:

Rycyk, A., Bolaji, D. A., Factheu, C., & Kamla Takoukam, A. (2022). Using transfer learning with a convolutional neural network to detect African manatee ( Trichechus senegalensis ) vocalizations. JASA Express Letters, 2(12), 121201. https://doi.org/10.1121/10.0016543

Florida Manatees

Manatee Vocal Behavior sample_Rycyk.wav

Florida manatees produce short, harmonically-rich sounds that can be described as chirps and squeaks (in the sound clip on the left you can hear multiple manatees vocalizing back and forth). Dr. Rycyk has ongoing work examining manatee vocalizations from animal-borne tags and passive acoustic monitoring stations. Her questions include:

Are Florida manatee vocalizations individually specific? If so, can the number of vocalizing manatees be estimated from static recording stations?
Can detection of manatee vocalizations be used to identify important areas for manatees?
How does manatee vocal behavior differ when they are alone compared to in groups?

Recent work in this area

Rycyk, Athena M., Berchem, Cora, and Marques, Tiago A. (2022) Estimating Florida manatee (Trichechus manatus latirostris) abundance using passive acoustic methods, JASA Express Letters, 2(5), 051202, https://doi.org/10.1121/10.0010495

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