Publication Date

Fall 2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Moss Landing Marine Laboratories

Advisor

Birgitte McDonald; Danuta Wisniewska; Sarah Smith

Abstract

To forage efficiently in patchy and unpredictable prey landscapes, marine predators must optimize energy intake while minimizing costs. Central place foragers like emperor penguins face greater energetic constraints during demanding periods of high investment like chick-rearing. I used high-resolution tri-axial acceleration, depth, and GPS data from 25 birds from two feeding seasons (2019 and 2022) to quantify prey capture attempts and a proxy for energy expenditure (overall dynamic body acceleration; ODBA) across dive types (epipelagic, mesopelagic, benthic), phases (descent, bottom, ascent), and over time at-sea. While prey capture attempts per minute did not differ when looking across dive types alone, the number of attempts was highly phase-dependent, with the highest numbers occurring in the bottom phase of mesopelagic and benthic dives. ODBA increased nonlinearly with prey capture attempts and showed the most complex patterns in shallower, epipelagic dives. Foraging attempts were impacted by short-term behavioral feedback where high numbers of recent attempts and brief surface intervals predicted greater prey capture efforts and higher ODBA in subsequent dives. Significant individual- and trip-level variation further highlight diverse foraging strategies. Together, these findings underscore the flexibility and context-dependent nature of emperor penguin foraging during a critical reproductive period.

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