Date of Award

Fall 12-2017

Degree Type


Degree Name

Doctor of Philosophy (PhD)



Committee Chair

Heidi Lyn

Committee Chair Department


Committee Member 2

Alen Hajnal

Committee Member 2 Department


Committee Member 3

Donald F. Sacco

Committee Member 3 Department


Committee Member 4

Nicole M. Phillips

Committee Member 4 Department

Biological Sciences

Committee Member 5

Deborah A. Giles


The social lives of animals are defined by group dynamics based on the nature and strength of associations and movements between individuals, often resulting in highly complex and interconnected social networks. However, understanding of how environmental variables may shape this structure is poorly understood. Within the inland waters of Washington State and southern Vancouver Island, British Columbia, mammal-eating Bigg’s (transient) killer whales occur in relatively small, but stable social groups. Group size and occurrence in recent years has increased, coinciding with a growing whale watching industry. Given the central importance of the social network within killer whale population dynamics, such as the maintenance of cooperation and cultural transmission of information, shifts in social network structure caused by environmental processes may have significant ecological and evolutionary consequences. Thus, it is reasonable to assume that the increased presence of Bigg’s killer whales within the Salish Sea leaves them susceptible to the various and growing anthropogenic pressures within this area. Utilizing a long-term data set (1987-2015), the objectives of this doctoral study are to: (1) identify the level(s) of preferred associations and social differentiation within Bigg’s societies relative to foraging specializations; (2) re-evaluate and compare historical measures and persistence of Bigg’s sociality, including demographic influences and dispersion patterns; and, (3) assess the extent to which individual sociality can predict received vessel traffic levels, as well as other variables driving targeted whale watching. The results of this work will better clarify the social dynamics and population structure of Bigg’s killer whales and will thus inform on proper management of this conservation unit. Likewise, the combined evaluation of social dynamics and anthropogenic pressures (vessel traffic) experienced by this population can provide key information that may enable managers to implement proper measures to mitigate anthropogenic impacts. Finally, the results of this analysis will serve as a platform for further evaluating the predator-prey dynamics of Bigg’s killer whale stocks that are central to the Salish Sea ecosystem.