Leopard Seals' Feeding Behavior Reshapes Antarctica’s Ecosystem

Contact: Kelly Craine, Baylor University Media and Public Relations, 254-297-9065
Follow us on Twitter: @BaylorUMedia

While leopard seals have long been labeled as dietary generalist predators, a new study led by researchers at Baylor University used whisker analysis to reveal that these Antarctic apex predators are anything but uniform in their feeding behavior. In fact, most individual leopard seals are specialists – and a few of them may be responsible for dramatic declines in key prey species like the Antarctic fur seal.

Published in the journal Ecology and Evolution, the research team found that while the species as a whole feeds on a broad range of prey, nearly 60% of individual seals consistently target specific types of prey—sometimes for years at a time—specializing at different trophic levels within the food web.

“This level of individual specialization is striking,” said lead author Emily Sperou, Ph.D. ’25 with Baylor’s Department of Biology and a post-doctoral fellow at the University of Rhode Island. “It shows that only a few seals may be responsible for significant impacts on prey populations, like the dramatic decline of the local Antarctic fur seal population.”

Using whiskers to track diet 

Researchers used whisker analysis, which is a powerful tool for studying the foraging behavior of marine predators over time. Since whiskers grow continuously and retain chemical signatures from the animal’s diet as they grow, each segment offers a time-stamped record of what the seal was eating during that period.

In this study, researchers analyzed 46 whiskers from 34 individual seals to reconstruct dietary patterns over 10 years.  The National Oceanic and Atmospheric Administration (NOAA) provided most of the whisker samples analyzed.  With these whiskers, the team was able to track variations in diet and identify consistent patterns of individual specialization – revealing not only what the seals ate, but how their feeding strategies changed – or didn’t – over time. This method provided unprecedented insight into the seals’ ecological roles and long-term impacts on prey populations.

Some seals, especially larger females, consistently foraged at the top of the food chain, primarily hunting fur seal pups and penguins. Others focused on fish, squid or krill. The findings show that body size and sex are key drivers in determining diet specialization.

Long-term consequences

This long-term focus on specific prey can have powerful ecological consequences. At Cape Shirreff, Antarctica, in the Southern Ocean, just 20 leopard seals are believed to have driven a catastrophic drop in the fur seal population, with up to 70% of pups lost to predators annually.

The study highlights the importance of understanding predator behavior at the individual level, especially in a rapidly changing climate. 

“Conservation strategies often assume that all apex predators behave similarly,” Sperou said. “But if only a few specialized individuals can reshape ecosystems, we need to rethink how we manage and protect these environments.”

The research also suggests that the feeding flexibility among some leopard seals could offer resilience against changing environmental conditions. Some seals switched their foraging strategies across years, likely adapting to shifts in prey availability or competition.

Updating management models

As climate change and human activities continue to alter ecosystems, the authors stress the importance of understanding individual behaviors within predator populations. Uniform policies may miss key dynamics if they overlook the outsized role of certain individual apex predators.

“This isn’t just about leopard seals,” Sperou said. “Many apex predators may show similar patterns, and it’s critical that we update our management models to reflect that.”

Acknowledgements

The U.S. Antarctic Program

The crew of the Lawrence M. Gould

The NOAA Antarctic Marine Living Resources Program

Ren Zhang, Ph.D. at the Baylor Stable Isotope Facility

Funding

The AMNH Lerner Gray Memorial Fund

American Philosophical Society Lewis and Clark Fund for Exploration and Field Research National Science Foundation 

About the Authors

Emily S. Sperou, Ph.D. ’25, is a marine mammal ecophysiologist interested in how individual variation in physiology and behavior influences life history strategies and ecological roles. Her Ph.D. research at Baylor University focused on leopard seals, using stable isotopes, hormone profiles and behavioral observations to examine intraspecific variation in foraging, reproductive strategies and stress physiology. 

Sarah Kienle, Ph.D. is an assistant professor of wildlife biology at the University of Rhode Island and the principal investigator of the Comparative Animal Ecophysiology Lab (CEAL). Her research centers on apex predators and their response to environmental change. 

In addition to Sperou and Kienle, the research team included: 

Douglas J. Krause, Ph.D., Antarctic Marine Living Resources Program, Ecosystem Science Division, National Oceanic and Atmospheric Administration (NOAA) Fisheries, La Jolla, CA.

Renato Borras-Chavez, Ph.D., Department of Biology, Post Doctoral Research for the Comparative Animal Ecophysiology Lab at Baylor University, Waco, TX, Department of Ecology, Pontificia Universidad Católica de Chile, Santiago, Chile and Environmental Fisheries Science Division, Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration (NOAA), Seattle, WA.

Patrick Charapata, Ph.D., Environmental Fisheries Science Division, Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration (NOAA), Seattle, WA and the Center for Species Survival, Georgia Aquarium, Atlanta, GA.

Daniel P. Costa, Ph.D., Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA. Center of Applied Ecology and Sustainability (CAPES).

Daniel E. Crocker, Ph.D., Department of Biology, Colorado State University, Fort Collins, CO.

Kerri J. Smith, Ph.D., Department of Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC.

Bradley Thompson, Department of Statistical Science, Baylor University, Waco, TX. 

Azana Best, Department of Biology, Baylor University, Waco, TX.

Jaelyn Anderson, Department of Biology, Baylor University, Waco, TX.

Michael E. Goebel, Ph.D., Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration (NOAA) Fisheries, La Jolla, CA, and Department of Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA.

Carolina A. Bonin, Ph.D., Department of Biological Science, Hampton University, Hampton, VA.

ABOUT BAYLOR UNIVERSITY

Baylor University is a private Christian University and a nationally ranked Research 1 institution. The University provides a vibrant campus community for more than 20,000 students by blending interdisciplinary research with an international reputation for educational excellence and a faculty commitment to teaching and scholarship. Chartered in 1845 by the Republic of Texas through the efforts of Baptist pioneers, Baylor is the oldest continually operating University in Texas. Located in Waco, Baylor welcomes students from all 50 states and more than 100 countries to study a broad range of degrees among its 12 nationally recognized academic divisions. Learn more about Baylor University at www.baylor.edu. 

ABOUT THE COLLEGE OF ARTS & SCIENCES AT BAYLOR UNIVERSITY

The College of Arts & Sciences is Baylor University’s largest academic division, consisting of 25 academic departments in the sciences, humanities, fine arts and social sciences, as well as 11 academic centers and institutes. The more than 5,000 courses taught in the College span topics from art and theatre to religion, philosophy, sociology and the natural sciences. The College’s undergraduate Unified Core Curriculum, which routinely receives top grades in national assessments, emphasizes a liberal education characterized by critical thinking, communication, civic engagement and Christian commitment. Arts & Sciences faculty conduct research around the world, and research on the undergraduate and graduate level is prevalent throughout all disciplines. Visit the College of Arts & Sciences website.