Date of Award

12-2014

Degree Type

Masters Thesis

Degree Name

Master of Arts (MA)

Department

Psychology

Committee Chair

Stan Kuczaj

Committee Chair Department

Psychology

Committee Member 2

Alen Hajnal

Committee Member 2 Department

Psychology

Committee Member 3

Sheree Watson

Committee Member 3 Department

Psychology

Abstract

Resident killer whales, Orcinus orca, of the Northeastern Pacific form stable kinship-based matrifocal associations and communicate with group-specific repertoires of discrete calls (dialects) that reflect these associations. The gradual fission of matrilines is usually consistent with dialect variations among groups that may manifest as differences in call usage at the repertoire level or subtle structural differences of the calls themselves. Therefore, matrilines that are more closely related tend to be more acoustically similar. Within the endangered community of Southern Resident killer whales (SRKWs), recent evidence shows that one particular group (L pod) exhibits the lowest rate of intrapod association and has significantly greater associations within matrilines than between matrilines - suggesting they may be undergoing a level of fission that is reflected in their acoustic repertoire. Call production of four L matrilines (L04, L21, L26, and L12) was analyzed over a five-year period (2007-2011). Results showed significant differences in proportional call use and call associations across matrilines, as well as acoustic similarity indices between matrilines that reflect the social fissioning exhibited by L pod. The large size, demography, and seasonal movements of L pod suggest that it may represent a potential conservation target pod and its protection could lead to benefits for the overall recovery of SRKWs. This is the first study to assess matrilineal dialect use of SRKWs and the subsequent knowledge of matrilineal dialect use of specific groups resulting from this study may prove useful for the future passive acoustic monitoring and management of this endangered population.

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