Dear colleagues, On behalf of myself and my co-authors, we are pleased to announce the publication of our new paper in PLoS ONE. Ames AE, Blackwell SB, Tervo OM, Heide-Jørgensen MP (2021) Evidence of stereotyped contact call use in narwhal (Monodon monoceros) mother-calf communication. PLoS ONE 16(8): e0254393. https://doi.org/10.1371/journal.pone.0254393 Abstract: Narwhals (Monodon monoceros) are gregarious toothed whales that strictly reside in the high Arctic. They produce a broad range of signal types; however, studies of narwhal vocalizations have been mostly descriptive of the sounds available in the species’ overall repertoire. Little is known regarding the functions of highly stereotyped mixed calls (i.e., biphonations with both sound elements produced simultaneously), although preliminary evidence has suggested that such vocalizations are individually distinctive and function as contact calls. Here we provide evidence that supports this notion in narwhal mother-calf communication. A female narwhal was tagged as part of larger studies on the life history and acoustic behavior of narwhals. At the time of tagging, it became apparent that the female had a calf, which remained close by during the tagging event. We found that the narwhal mother produced a distinct, highly stereotyped mixed call when separated from her calf and immediately after release from capture, which we interpret as preliminary evidence for contact call use between the mother and her calf. The mother’s mixed call production occurred continually over the 4.2 day recording period in addition to a second prominent but different stereotyped mixed call which we believe belonged to the narwhal calf. Thus, narwhal mothers produce highly stereotyped contact calls when separated from their calves, and it appears that narwhal calves similarly produce distinct, stereotyped mixed calls which we hypothesize also contribute to maintaining mother-calf contact. We compared this behavior to the acoustic behavior of two other adult females without calves, but also each with a unique, stereotyped call type. While we provide additional support for individual distinctiveness across narwhal contact calls, more research is necessary to determine whether these calls are vocal signatures which broadcast identity. The publication can be open-accessed via https://doi.org/10.1371/journal.pone.0254393 or you can email a request for a PDF to aames@oceanografic.org<mailto:aames@oceanografic.org>. Many thanks for your interest in the article, and thank you to the PLOS ONE editors and the reviewers of the publication for their contributions to the finished article. Best, Audra -- Audra Ames, Ph.D. Research Scientist, Fundación Oceanografic T: (+34) 96 1975526 Fundación Oceanogràfic de la Comunitat Valenciana C/ Eduardo Primo Yúfera (Científic), 1B 46013 Valencia Spain