Dear colleagues, My co-authors and I are pleased to share the recent publication of our paper in Proceedings of the National Academy of Sciences: Abrahms, B., Hazen, E.L., Aikens, E.O., Savoca, M.S., Goldbogen, J.A., Bograd, S.J., Jacox, M.G., Irvine, L.M., Palacios, D.M., and Mate, B.R. Memory and resource tracking drive blue whale migrations. *Proceedings of the National Academy of Sciences*, DOI: https://doi.org/10.1073/pnas.1819031116. Abstract: In terrestrial systems, the Green Wave Hypothesis posits that migrating animals can enhance foraging opportunities by tracking phenological variation in high quality forage across space (i.e., ‘resource waves’). To track resource waves, animals may rely on proximate cues and/or memory of long-term average phenologies. Although there is growing evidence of resource tracking in terrestrial migrants, such drivers remain unevaluated in migratory marine megafauna. Here we present a novel test of the Green Wave Hypothesis in a marine system. We compare ten years of blue whale movement data with the timing of the spring phytoplankton bloom resulting in increased prey availability in the California Current Ecosystem, allowing us to investigate resource tracking both contemporaneously (response to proximate cues) and based on climatological conditions (memory) during migrations. Blue whales closely tracked the long-term average phenology of the spring bloom, but did not track contemporaneous green-up. In addition, blue whale foraging locations were characterized by low long-term habitat variability and high long-term productivity compared to contemporaneous measurements. Results indicate that memory of long-term average conditions may have a previously underappreciated role in driving migratory movements of long-lived species in marine systems, and suggest that these animals may struggle to respond to rapid deviations from historical mean environmental conditions. Results further highlight that ecological theory of migration is conserved across marine and terrestrial systems. Understanding the drivers of animal migration is critical for assessing how environmental changes will affect highly mobile fauna at a global scale. An online version of the article can be accessed here: https://www.pnas.org/content/early/2019/02/19/1819031116 The underlying data have also been published as a Movebank Repository under a Creative Commons Zero license as: Mate BR, Palacios DM, Irvine LM, Follett TM (2019) Data from: Behavioural estimation of blue whale movements in the Northeast Pacific from state-space model analysis of satellite tracks. Movebank Data Repository. DOI: https://doi.org/10.5441/001/1.5ph88fk2. Best wishes, Briana Abrahms and co-authors