Nutritional Content of Rhinoceros Auklet Bill Loads

Dustin E Taylor


An adult Rhinoceros Auklet (Cerorhinca monocerata) can only catch and carry a limited amount of prey to their nestlings after a foraging trip. The auklets therefore must maximize their efficiency by bringing back the most proportionally nutritious prey items to their nestlings. The prey carried back to the nesting sites (known as a ‘bill load’) can contain whole fish, as well as parts, most commonly fish heads. This study is aimed to determine whether returning with just heads to the nestlings was proportionally more nutritious than bringing back a whole fish. In order to answer this question, heads and bodies of the prey items were analyzed for protein, lipid, mineral content, and caloric value by NOAA chemists. The bill loads were (by fish) 44% capelin (Mallotus villosus) (40 fish), 36% Pacific sand lance (Ammodytes hexapterus) (32 fish), 10% Pacific herring (Clupea pallasii) (9 fish), and 10% greenling (Hexagrammos spp.) (9 fish). Data on protein, lipid, mineral content, and caloric value were not available at time of submission.


Aquaculture and Fisheries | Biology | Marine Biology | Nutrition | Ornithology | Zoology


Bonita Nelson

Lab site

National Oceanic and Atmospheric Administration Alaska Fisheries Science Center (NOAA AFSC)

Funding Acknowledgement

This material is based upon work supported by the S.D. Bechtel, Jr. Foundation and by the National Science Foundation under Grant No. 0952013. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the S.D. Bechtel, Jr. Foundation or the National Science Foundation. This project has also been made possible with support of the National Marine Sanctuary Foundation. The STAR program is administered by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the California State University (CSU).



URL: https://digitalcommons.calpoly.edu/star/132


To view the content in your browser, please download Adobe Reader or, alternately,
you may Download the file to your hard drive.

NOTE: The latest versions of Adobe Reader do not support viewing PDF files within Firefox on Mac OS and if you are using a modern (Intel) Mac, there is no official plugin for viewing PDF files within the browser window.