Date of Award

January 2016

Degree Type

Open Access Thesis

Document Type

Master Thesis

Degree Name

Master of Science (MS)



First Advisor

Robert W. Mitchell

Department Affiliation


Second Advisor

Radhika Makecha

Department Affiliation


Third Advisor

Robert G. Brubaker

Department Affiliation



My thesis concerns observations of play activities from videotapes of Galápagos sea lions on San Cristóbal Island from mid-summer of 2008. I begin with a discussion of ideas about play and types of play, elaborate the conceptual system of projects and routines in play, and provide a brief description of sea lion taxonomy and forms of play specific to Galápagos sea lions. Observing approximately 713 minutes of videotapes, I coded approximately 161.5 minutes of play projects and routines. Of the 713 minutes, 241 minutes were used in training, and 472 were coded independently by two coders for reliability. The two coders observed approximately 141 minutes of play. For the presence of particular projects and routines at approximately the same time, reliability was 100%; for agreement about the temporal extent of projects and routines, reliability was 96% (though some infrequent projects and routines had low agreement); overall, Cohen’s kappa was .97. I observed five solitary play projects (lolling, twirling, object play, jumping, and surfing), and four social play routines (playfighting, playchasing, playwrestling, and king of the hill—a form of playful boundary defense). Of these, lolling and twirling had not been previously coded as play in the scientific literature. The most common play activities were lolling and playfighting. Social object play, sexual play, and boundary defense seem likely to be present in all sea lion species, but I observed no evidence of the first two, and only one variant of boundary defense (king of the hill), in the videotaped Galápagos sea lions.