Dear MARMAM community, On behalf of my coauthors, I am pleased to share our recent publication in Movement Ecology: Kratofil, M.A., Shaff, J.F., Hoffbauer, H.K., Cantor, M., Hill, M.C., & Baird, R.W. (2026). Ecological contexts of diving behavior in Hawaiian false killer whales. Movement Ecology, 14, 17. https://doi.org/10.1186/s40462-026-00630-4. The abstract is copied below, and the open-access PDF can be downloaded at https://link.springer.com/article/10.1186/s40462-026-00630-4 Background Predator movements vary across different ecological contexts, offering valuable insights into their foraging strategies. However, studying these contexts in marine predators is challenging due to the difficulty of observing them and their prey over sufficient spatiotemporal scales. Using bio-loggers and detailed life history information, we investigated abiotic and biotic factors shaping the diving behavior of a highly social apex predator-the false killer whale (Pseudorca crassidens)-around the Hawaiian Archipelago where three partially sympatric, genetically differentiated populations coexist. Methods We deployed time-depth recorders (n=5) and depth-transmitting satellite tags (n=16) on false killer whales between 1999-2025 to describe diving at multiple spatiotemporal scales and ecological contexts. We fit generalized additive mixed-effects models to examine relationships between dive metrics and temporal and spatial proxies of prey distribution. Dive metrics were compared across demographic traits (sex, population, relative size) to assess potential drivers of behavioral variability. Results False killer whales spent most of their time in near-surface waters and frequently dove within the epipelagic zone. Individuals exhibited various dive types within and among different habitats, including near-seafloor and deep (> 1,000 m; record maximum of 1,424 m) diving behavior. Dive rates and depths were highest during daylight hours and full moons, although with significant inter-individual variation. Dive depth increased with current magnitude and mixed layer depth and decreased with lagged surface chlorophyll-a concentration. Larger individuals tended to dive deeper, although with high variation across demographic groups. These findings offer key insights into potential drivers of diving behavior, albeit with small effect sizes. Conclusions We present the first comprehensive description of diving behavior for this species, which was characterized by variable temporal patterns, in contrast to sympatric species that are known to exploit diel vertically migrating prey. The diversity of dive types across habitats, along with trends between dive metrics and oceanographic variables, suggests that false killer whales may adjust their vertical movements to target different prey and environmental conditions. Please feel free to reach out with questions or a PDF copy of the paper. Best, Michaela A. Kratofil Research Biologist Cascadia Research Collective Olympia, WA Learn more<https://cascadiaresearch.org/> <https://cascadiaresearch.org/> | Support our work<https://cascadiaresearch.org/donations/> [cid:image001.png@01DCBAC5.EAEE1F30]
