Dear Marmam Community, My co-authors and I are pleased to share our new paper, "Divergent foraging strategies between populations of sympatric matrilineal killer whales", published in *Behavioral Ecology*. The article is freely available, here <https://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arad002/7069400?utm_source=advanceaccess&utm_campaign=beheco&utm_medium=email>. https://doi.org/10.1093/beheco/arad002 Tennessen, J.B., Holt, M.M., Wright, B.M., Hanson, M.B., Emmons, C.K., Giles, D.A., Hogan, J.T., Thornton, S.J., Deecke, V.B. 2023. Divergent foraging strategies between populations of sympatric matrilineal killer whales, *Behavioral Ecology*, arad002, https://doi.org/10.1093/beheco/arad002 Abstract In cooperative species, human-induced rapid environmental change may threaten cost-benefit tradeoffs of group behavioral strategies that evolved in past environments. Capacity for behavioral flexibility can increase population viability in novel environments. Whether the partitioning of individual responsibilities within social groups is fixed or flexible across populations is poorly understood, despite its relevance for predicting responses to global change at the population and species levels and designing successful conservation programs. We leveraged bio-logging data from two populations of fish-eating killer whales to quantify patterns of fine-scale foraging movements and their relationships with demography. We reveal striking inter-population differences in patterns of individual foraging behavior. Females from the endangered Southern Resident (SRKW) population captured less prey and spent less time pursuing prey than SRKW males or Northern Resident (NRKW) females, whereas NRKW females captured more prey than NRKW males. The presence of a calf (<= 3 y) reduced the number of prey captured by adult females from both populations, but disproportionately so for SRKW. SRKW adult males with a living mother captured more prey than those whose mother had died, whereas the opposite was true for NRKW adult males. Across populations, males foraged in deeper areas than females, and SRKW captured prey deeper than NRKW. These population-level differences in patterns of individual foraging behavior challenge the existing paradigm that females are the disproportionate foragers in gregarious resident killer whales, and demonstrate considerable variation in the foraging strategies across populations of an apex marine predator experiencing different environmental stressors. Please contact Jennifer Tennessen with questions or to request a pdf, at jtenness@uw.edu. Cheers, Jennifer Tennessen -- Jennifer Beissinger Tennessen, Ph.D. Senior Research Scientist Center for Ecosystem Sentinels Department of Biology University of Washington Life Sciences Building, Box 351800 Seattle, WA 98195 jtenness@uw.edu https://ecosystemsentinels.org/