Dear colleagues, On behalf of my co-authors, I am pleased to announce our new publication: Zahn MJ, Laidre KL, Stilz P, Rasmussen MH, Koblitz JC (2021) Vertical sonar beam width and scanning behavior of wild belugas (*Delphinapterus leucas*) in West Greenland. PLoS ONE 16(9): e0257054. https://doi.org/10.1371/journal.pone.0257054 The article is open access and can be found here: https://doi.org/10.1371/journal.pone.0257054 ABSTRACT: Echolocation signals of wild beluga whales (*Delphinapterus leucas*) were recorded in 2013 using a vertical, linear 16-hydrophone array at two locations in the pack ice of Baffin Bay, West Greenland. Individual whales were localized for 4:42 minutes of 1:04 hours of recordings. Clicks centered on the recording equipment (i.e. on-axis clicks) were isolated to calculate sonar parameters. We report the first sonar beam estimate of *in situ* recordings of wild belugas with an average -3 dB asymmetrical vertical beam width of 5.4°, showing a wider ventral beam. This narrow beam width is consistent with estimates from captive belugas; however, our results indicate that beluga sonar beams may not be symmetrical and may differ in wild and captive contexts. The mean apparent source level for on-axis clicks was 212 dB pp re 1 μPa and whales were shown to vertically scan the array from 120 meters distance. Our findings support the hypothesis that highly directional sonar beams and high source levels are an evolutionary adaptation for Arctic odontocetes to reduce unwanted surface echoes from sea ice (i.e., acoustic clutter) and effectively navigate through leads in the pack ice (e.g., find breathing holes). These results provide the first baseline beluga sonar metrics from free-ranging animals using a hydrophone array and are important for acoustic programs throughout the Arctic, particularly for acoustic classification between belugas and narwhals (*Monodon monoceros*). Please feel free to contact me at mzahn@uw.edu if you have any questions. Best, Marie Zahn -- *MARIE ZAHN | *she/her Graduate Student, Laidre Lab <https://staff.washington.edu/klaidre/> School of Aquatic and Fishery Sciences University of Washington