Victoria Dina

Date of Award

2021

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Rycyk, Athena

Area of Concentration

Marine Biology

Abstract

As growing anthropogenic noise pollution influences aquatic species' behavior and survival, it is crucial to identify what specific marine ecology aspects are affected by human activity. One keystone species of great interest is the otter, specifically the North American river otter whose ecological role is evident in the watersheds they call home. This study provides the first quantitative assessment of the underwater vocalizations of North American river otters, Lontra Canadensis (Schreber 1777), and examines the behavioral contexts within which these vocalizations are produced. Three captive North American river otters' vocal behavior was captured using a hydrophone in conjunction with a handheld recorder. Stationed outside the otters' enclosure was a video camera to verify otter positions inside or outside the water. Vocalizations were aurally assessed before analysis through Raven Pro in conjunction with video data of the otter activity during vocal production. The use of vocal communication above and below the water exemplifies the extent of otters' behavioral and social flexibility. There were ten vocalization bouts recorded where all three otters were underwater. These calls were composed of quick successions of low-frequency grunts with harmonics ranging from 50 to 600 Hz. Underwater grunts had a mean duration of 0.13 seconds for a total vocalization bout length of 1.12 seconds on average. These results are consistent with the minimal previous literature on underwater vocalizations of the giant otter, a related member of the subfamily Lutrinae.

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