Date of Award

Summer 8-2016

Degree Type


Degree Name

Doctor of Philosophy (PhD)



Committee Chair

Stanley A. Kuczaj

Committee Chair Department


Committee Member 2

David J. Echevarria

Committee Member 2 Department


Committee Member 3

Tammy Greer

Committee Member 3 Department


Committee Member 4

Donald Sacco

Committee Member 4 Department


Committee Member 5

Heidi Lyn

Committee Member 5 Department



Florida manatees inhabit waterways where motorized boats are common. Although manatee mortalities resulting from boat strikes are well documented, the effect of boat noise on some manatee behaviors, including rest, has not been investigated. This study focuses on rest behavior and used a playback experiment with four manatees at the Lowry Park Zoo in Florida. We tested their responses to playback stimuli of either boat noise, silence, or manatee calls. A playback trial was initiated when the focal animal showed behavioral characteristics of rest.

Results showed that rest was interrupted in response to the playback of boat noise for each of the manatees. Distinct reactions to playback stimuli were exhibited where for three of the four, rest was interrupted in response to manatee calls, however, rest was not interrupted for any manatee during playback of silence. Boat noise resulted in manatees moving away from the speaker, and manatee calls resulted in their moving toward the speaker. Manatees showed individual differences in their post-playback behaviors in terms of breathing patterns, rest episode duration, and latency of reactions. However, these differences were not statistically significant and did not reflect a specific type of stimuli (boat noise, manatee calls, or silence).

Results indicate that rest could be interrupted immediately after playback in response to both biologically significant sounds (e.g., manatee calls) and anthropogenic sounds (e.g., boat noise), though reactions differed according to sound type. Overall, no rest behavior or rest episode was affected in any significantly different way by type of playback stimuli, which indicates that sleep interruptions at such low levels (85–97 dB re 1 µPa) and of such short duration did not have a significant effect on manatees’ overall rest behavior or rest duration.