ORIGINAL RESEARCH article
Front. Bird Sci.
Sec. Bird Ecology and Behavior
Volume 4 - 2025 | doi: 10.3389/fbirs.2025.1587072
This article is part of the Research TopicBioenergetic and Behavioral Effects of Rapid Anthropogenic Change and Eco-evolutionary ImplicationsView all 4 articles
A Decade of Diving: Responses of Cassin's auklets to variable foraging conditions in the California Current System
Provisionally accepted
Nina Jane Karnovsky1*
Pete Warzybok2
Andre Cavalcanti1
Johanna Hardin1Zachary W Brown1,3Eleanor Caves1,4
Clare M Flynn1,5Gail Gallaher1Nicole McDuffie1Kristina McOmber1,6Russell Bradley2,7Meredith Elliott2Ben Saenz2,8
Jaime Jahncke2- 1Pomona College, Claremont, United States
- 2Point Blue Conservation Science, Petaluma, California, United States
- 3Tidelines Institute, Gustavus, United States
- 4Brown University, Providence, Rhode Island, United States
- 5Stony Brook University, Stony Brook, New York, United States
- 6University of Manitoba, Winnipeg, Manitoba, Canada
- 7Wildlife Management, Natural Resources Division, California State Parks, CA, Sacramento, United States
- 8Biota.earth, Berkeley, United States
Select one of your emails
You have multiple emails registered with Frontiers:
Notify me on publication
Please enter your email address:
If you already have an account, please login
You don't have a Frontiers account ? You can register here
We investigated how a planktivorous seabird adjusts its foraging behavior in response to different levels of prey biomass. We studied the diving behavior of Cassin’s auklets (Ptychoramphus aleuticus) breeding on Southeast Farallon Island and feeding in the highly variable California Current System. In recent years Cassin’s auklets have experienced mass mortality events and complete reproductive failure due to anomalous atmospheric and oceanographic conditions. We hypothesized that in years with low prey biomass, Cassin’s auklets work harder to collect food for themselves and for their chick and that reproductive success is lower during those years. To test this hypothesis, we equipped 133 Cassin’s auklets with Time Depth Recorders from 2008 – 2017. We estimated krill biomass levels in the top 30 m during oceanographic cruises carried out where Cassin’s auklets foraged. We measured the annual number of chicks fledged per pair. In years with high prey biomass reproductive success was very high and Cassin’s auklets collected prey in fewer, deeper and longer dives. They spent more time in the bottom of their dives and more time underwater. When krill biomass was low, they made shallow, shorter dives and a higher number of these dives during their foraging trips. Variability in the California Current System greatly influenced the diving behavior and reproductive success of the Cassin’s auklets. Climate anomalies that lead to extremely low krill biomass are expected to become more frequent. Cassin’s auklets are likely not going to able to increase their foraging effort enough to be able to survive and reproduce.
Keywords: Cassin's Auklets, Southeast Farallon Island, California Current system, Time depth recorders, diving behavior, krill, seabird, Climate Change
Received: 03 Mar 2025; Accepted: 12 May 2025.
Copyright: © 2025 Karnovsky, Warzybok, Cavalcanti, Hardin, Brown, Caves, Flynn, Gallaher, McDuffie, McOmber, Bradley, Elliott, Saenz and Jahncke. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Nina Jane Karnovsky, Pomona College, Claremont, United States
Disclaimer: All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article or claim that may be made by its manufacturer is not guaranteed or endorsed by the publisher.