Thesis defense by Mason Cole – November 6th Livestream


"Detecting Feeding and Estimating the Energetic Costs of Diving in California Sea Lions (Zalophus californianus) Using 3-Axis Accelerometers"
A Thesis Defense by Mason Cole

The Vertebrate Ecology Lab

MLML Live-Stream | November 6, 2020 at 12 pm

     There is written evidence that when Mason was in third grade he wanted to be an "adventure biologist!", which sounds like an awesome gig. He promptly forgot this dream and ended up pursuing a pre-med undergrad track (B.S. in General Biology from UCSD in 2010), only to change his mind again after graduating. Drawn by wilderness and adventure, and hoping to somehow stumble upon a fulfilling career choice, he booked it to Chilean Patagonia and wandered northward through mountains, diverse volunteer gigs in conservation biology, and his entire bank account before crawling reluctantly back to California. Two years later, armed with experience in both tough field work and poverty, he was ready to take on grad school!  Through hard work and perfect timing he ended up in Dr. McDonald's Vertebrate Ecology Lab, where he couldn't be happier. It was during this time (2015-2020) that Mason's 3rd grade "adventure biologist!" card was unearthed like a fossil from sedimentary layers of nostalgic keepsakes in his parents' home...COINCIDENCE? I think not.
     Mason's research interests currently include the foraging ecology and energetics of large predators, with ample room for broadening this horizon in the future. Mason is also passionate about scientific outreach, outdoor education, and active conservation (habitat conservation and restoration), and has worked (or is currently working) professionally in each of these avenues.

Thesis Abstract:

Knowledge of when animals feed and the energetic costs of foraging is key to understanding their foraging ecology and energetic trade-offs.  Despite this importance, our ability to collect these data in marine mammals remains limited.  In this thesis, I address knowledge gaps in both feeding detection and fine-scale diving energetic costs in a model species, the California sea lion (Zalophus californianus).  In Chapter 1 I developed and tested an analysis method to accurately detect prey capture using 3-axis accelerometers mounted on the head and back of two trained sea lions.  An acceleration signal pattern isolated from a ‘training’ subset of synced video and acceleration data was used to build a feeding detector. In blind trials on the remaining data, this detector accurately parsed true feeding from other motions (91-100% true positive rate, 0-4.8% false positive rate), improving upon similar published methods.  In Chapter 2, I used depth and acceleration data to estimate the changing body density of 8 wild sea lions throughout dives, and used those data to calculate each sea lion’s energetic expenditure during descent and ascent at fine temporal scales.  Energy expenditure patterns closely followed the influence of buoyancy changes with depth. Importantly, sea lions used more energy per second but less energy per meter as dive depth increased, revealing high costs of deep diving.  Combined, these chapters further our understanding of California sea lion foraging ecology and provide new methods to aid similar future studies.

Mason Cole Presents: Detecting Feeding and Estimating the Energetic Costs of Diving in California Sea Lions (Zalophus californianus) Using 3-Axis Accelerometers