January 24, 2024: A Tale of Two Killer Whale Populations


Comparing and Contrasting Southern Resident and Bigg’s Killer Whales in the Salish Sea

Monica Wieland ShieldsSpeaker: Monika Wieland Shields, co-founder and director of the Orca Behavior Institute (OBI), a non-profit based on San Juan Island, Washington whose mission is to inspire conservation of wild killer whales through non-invasive research, bold advocacy, and science-based education.
Orcas, also known as killer whales, are an iconic species of the Pacific Northwest, but did you know we have two distinct populations that live in our local waters? Despite having the same geographic range, the Southern Resident and Bigg’s killer whale populations don’t interact or interbreed, having such different cultures and some suggest they should be designated as two different species.

Everything from diet and acoustic communication to behavior and travel patterns is different between these two populations. In her talk, Monika will review just how unique each group of orcas is, introducing you to some of the individual whales along the way. She will also explain why the Bigg’s killer whales are thriving, with a steadily growing population over the last 30+ years, while the Southern Resident population continues to struggle and decline over that same time period.

By comparing and contrasting these two Salish Sea orca populations, we can learn a lot about the human impact on the world around us, and what it takes to successfully live in close proximity to the ocean’s apex predator.


Monika has been observing and studying orcas in the Salish Sea since 2000. She knows Salish Sea killer whales on a personal level, having gotten to know them and their family histories through hundreds of encounters in the field. She regularly shares their stories through blogs, social media posts, and photography.

Monika has helped document dramatic shifts in both the endangered fish-eating Southern Resident killer whale population and the thriving mammal-eating Bigg’s killer whale population. Her peer-reviewed scientific publications cover topics including acoustic communication, shifting habitat usage, and behavior of regional killer whales. She is also the author of the book “Endangered Orcas: The Story of the Southern Residents”.