Role Reversal and Behavioral Symmetry in Rookery-Based Social Play of Young California Sea Lions (Zalophus californianus)

Date of Award

5-2026

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Social Sciences

Second Advisor

Cook, Peter

Keywords

Juvenile Behavior, Marine Mammal, Play Fighting, Role Reversal, Sea lions, Social Play, Zalophus californianus

Area of Concentration

Marine Mammal Science

Abstract

Play behavior is present in the early lives of all mammals and is thought to contribute to cognitive, social, and physical development. California sea lions are a long-lived, behaviorally flexible species with an extended juvenile period. As such, play behavior may be particularly relevant to their long-term learning, including understudied social learning processes. We developed an ethogram and applied it to 40 continuous play bouts involving primarily juvenile California sea lions observed on the beach of a breeding rookery. We then quantified the occurrence and duration of specific behaviors and assessed within-bout symmetry of dominance behaviors, with a focus on role reversal and participant body size. We collected video data opportunistically in the intertidal zone at Año Nuevo Island, San Mateo County, CA, in fall 2025. Behavioral data were coded into ethograms informed by prior mammalian play literature and otariid behavioral observations. Behavioral expression varied considerably across bouts, with play bouts showing consistent initiating and terminating behaviors despite high variability in overall behavioral distribution. Participants showed evidence of role reversal, with the occurrence and duration of dominant behaviors trending toward symmetry across participants. Within bouts, relatively smaller individuals expressed dominant behaviors at a marginally higher frequency. It appears that shore-based social play among California sea lions consists predominantly of play-fighting bouts. These bouts are behaviorally variable and hierarchically symmetrical, with evidence suggesting role reversal. The tendency for smaller individuals to display equal or greater dominance during role reversal may reflect behavioral inhibition in larger partners, a pattern reported in the play behavior of other carnivorous mammals.

Rights

The author has not granted New College of Florida the nonexclusive right to archive, make accessible, and distribute for educational purposes this work in whole or in part in all forms of media, now or hereafter known. The copyright of this work remains with the author.

This document is currently not available here.

Share

COinS