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Phoebe Sonia Hodson is a 2025 graduate of the MS Program in Environmental Studies at Antioch University, New England.

Thesis Committee:

Dawn Murray, Ph.D., Chairperson

Eric Angel Ramos, Ph.D.

Beth Brady, Ph.D.

Keywords

Acoustic communication, playback, Greater Caribbean manatee, behavior, Florida manatee, Trichechus manatus

Document Type

Thesis

Publication Date

2025

Abstract

The behavioral response of the wild Greater Caribbean manatee (Trichechus manatus manatus) to the acoustic vocalizations of their closely related subspecies, the Florida manatee (Trichechus manatus latirostris), was examined for the first time in Placencia Lagoon, Maya Beach, Belize. The main goal of this study was to determine how vocalizations from conspecifics influence the behavior of the wild Greater Caribbean manatee and how this behavioral change may give insight into the functionality of manatee vocalizations. Three call types (squeak, squeal and high squeak) and chewing sounds were played to varying size aggregations of manatees. Broad behavioral states were observed in 20-second intervals before, during and after playback sessions. A Markov Chain model was used to determine any behavioral changes between the before, during, and after phases of the playback study, and transitional matrices were created to best portray our results. When wild Greater Caribbean manatees were exposed to the squeal, squeak, and chewing sounds there was no change in behavior observed; however, when they were exposed to the high squeak call, there were multiple changes in behavior observed. Our combined results showed that cow-calf pairs would travel to the sound source together to investigate, and in some instances the cow would leave her calf behind to travel to the sound source. The response to the high squeak call type supports the theory that this call type is used by calves in distress when separated from their mother. This dissertation is available in open access at AURA: Antioch University Repository and Archive, https://aura.antioch.edu/.

Comments

ORCID No: 0009-0000-1319-9088

Phoebe Sonia Hodson, MS (she/her/hers), is devoted to marine science and conservation. While completing her BS in Marine Science at the University of Maine – Orono, she worked at the Aquaculture Research Center with Dr. Heather Hamlin on her capstone project focused on raising abalone in a recirculating aquaculture facility and worked in Dr. David Townsend’s lab supporting doctoral students with phytoplankton research. She has also worked at the Darling Marine Center with Dr. Jeffrey Runge conducting zooplankton grazing experiments. Her master’s thesis research, which was supported by an Institute for International Conservation grant and included a research internship with the Temporal Trends in Manatee Acoustics Lab in collaboration with Rockefeller University, she explored acoustic and behavioral responses of the wild Greater Caribbean manatee (Trichechus manatus manatus) in Maya Beach, Belize to playbacks of the closely related Florida manatee (Trichechus manatus latirostris).

Currently, she has taken her experience with marine acoustics to the Maine Department of Marine Resources (DMR) Marine Mammal Research Division in Boothbay Harbor, Maine. There she works as an acoustic analyst studying the vocalizations of the endangered North Atlantic right whale. Through her work at DMR, she hopes to help find strategies to ameliorate further decline in right whale populations and effect a better future for marine species not only in the Gulf of Maine but in all the world’s oceans.

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