Dear colleagues, my co-authors and I are pleased to announce two new publications on reversal learning in harbor seals: *Erdsack N, Dehnhardt G, Hanke FD (2022) Serial visual reversal learning in harbor seals (**/Phoca vitulina/**). Animal Cognition doi:10.1007/s10071-022-01653-1* Progressively improving performance in a serial reversal learning (SRL) test has been associated with higher cognitive abilities and has served as a measure for cognitive/behavioral flexibility. Although the cognitive and sensory abilities of marine mammals have been subject of extensive investigation, and numerous vertebrate and invertebrate species were tested, SRL studies in aquatic mammals are sparse. Particularly in pinnipeds, a high degree of behavioral flexibility seems probable as they face a highly variable environment in air and underwater. Thus, we tested four harbor seals in a visual two-alternative forced-choice discrimination task and its subsequent reversals. We found significant individual differences in performance. One individual was able to solve 37 reversals showing progressive improvement of performance with a minimum of 6 errors in reversal 33. Two seals mastered two reversals, while one animal had difficulties in learning the discrimination task and failed to complete a single reversal. In conclusion, harbor seals can master an SRL experiment; however, the performance is inferior to results obtained in other vertebrates in comparable tasks. Future experiments will need to assess whether factors such as the modality addressed in the experiment have an influence on reversal learning performance or whether indeed, during evolution, behavioral flexibility has not specifically been favored in harbor seals. https://link.springer.com/article/10.1007/s10071-022-01653-1 *Niesterok B, Martin S, Hildebrand L, Dehnhardt G, Hanke FD (2022) Well-developed spatial reversal learning abilities in harbor seals (**/Phoca vitulina/**). Animal Cognition. doi:10.1007/s10071-022-01651-3* In this study, behavioral plasticity in harbor seals was investigated in spatial reversal learning tasks of varying complexities. We started with a classic spatial reversal learning experiment with no more than one reversal per day. The seals quickly learned the task and showed progressive improvement over reversals, one seal even reaching one-trial performance. In a second approach, one seal could complete multiple reversals occurring within a session. Again, a number of reversals were finished with only one error occurring at the beginning of a session as in experiment 1 which provides evidence that the seal adopted a strategy. In a final approach, reversals within a session were marked by an external cue. This way, an errorless performance of the experimental animal was achieved in up to three consecutive reversals. In conclusion, harbor seals master spatial, in contrast to visual, reversal learning experiments with ease. The underlying behavioral flexibility can help to optimize behaviors in fluctuating or changing environments. https://link.springer.com/article/10.1007/s10071-022-01651-3 Both studies are open access and published as part of a Special Issue on Marine Mammal Cognition. Best regards, Nicola Erdsack -- ********************************** Nicola Erdsack, Ph.D. Postdoc Manatee Research Mote Marine Laboratory & Aquarium 1600 Ken Thompson Pkwy Sarasota, FL 34236 phone +1-941-388-4441, ext. 248 cell +1-941-284-0708 erdsack@mote.org https://mote.org/staff/member/nicola-erdsack