Evidence of stereotyped contact call use in narwhal (Monodon monoceros) mother-calf communication

PLoS One. 2021 Aug 27;16(8):e0254393. doi: 10.1371/journal.pone.0254393. eCollection 2021.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arctic Regions
  • Female
  • Vocalization, Animal / physiology*
  • Whales / physiology*

Associated data

  • figshare/10.6084/m9.figshare.15050277.v1

Grants and funding

This study is part of the Northeast Greenland Environmental Study Program funded by the Mineral License and Safety Authority and the Environmental Agency for Mineral Resource Activities. Additional funding was provided by the Greenland Institute of Natural Resources and the Carlsberg Foundation (2013_01_0289 and CF14-0169). The salary of AEA was funded by Fundación Oceanogràfic de la Comunitat Valenciana. SBB is employed by Greeneridge Sciences, Inc., an independent, commercial contracting company that performs studies of the interactions between underwater sounds and marine vertebrates. Greeneridge Sciences, Inc., provided support in the form of analysis equipment for SBB but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. The specific roles of these authors are articulated in the "author contributions" section.