Graduation Date

Spring 2022

Document Type



Master of Science degree with a major in Biology

Committee Chair Name

Dawn Goley

Committee Chair Affiliation

HSU Faculty or Staff

Second Committee Member Name

Paul E. Bourdeau

Second Committee Member Affiliation

HSU Faculty or Staff

Third Committee Member Name

Micaela Szykman Gunther

Third Committee Member Affiliation

Community Member or Outside Professional

Fourth Committee Member Name

Daniel P. Costa

Subject Categories



The King Range colony is the northernmost successful and expanding breeding site for northern elephant seals (Mirounga angustirostris). To evaluate the composition and growth of this colony, I conducted systematic surveys recording counts, age classes, births, and resighting seals with individually identifiable flipper tags. The timing of life-history events (breeding, molting, and resting) of all elephant seal sex and age groups at the King Range was consistent with observations at other colonies. Colony counts during breeding and molting have increased steadily over the 4-year study period (2018-2021), and pup production has increased by 87% since the first year of monitoring. The main driver of colony growth was juvenile elephant seals dispersing from colonies in central California, as revealed by the majority of tag resights being of juveniles from Point Reyes. Juvenile seasonal haul out behavior differed with a higher percentage of ‘new’ juveniles seen in the fall than in the spring and higher variability in seasonal arrival date, tenure, and number of visits in the fall resting haul out than during the spring molt. This difference may be due to the extreme physiological demands on elephant seals during their spring molt, which is absent during the fall. This growing northern elephant seal colony will likely become a seed colony for further northern dispersal as this species continues to be impacted by global climate change. By documenting juvenile dispersal and colony growth, I provide information to managers and the public for use in preparing and managing conflicts that might arise with the predicted expansion and redistribution of this species.

Citation Style



Thesis/Project Location