The ‘‘gunshot’’ sound produced by male North Atlantic right whales and its potential function in reproductive advertisement

North Atlantic right whales (Eubalaena glacialis) commonly use sound to mediate social interactions between individuals. Surface active groups (SAGs) are the most commonly observed social interaction on the summer feeding grounds. These groups are typically composed of an adult female with two or more males engaged in social behavior at the surface. Several distinct types of sounds have been recorded from these groups. One sound commonly recorded from these groups is a brief broadband sound, referred to as a gunshot sound because it sounds like a rifle being fired. This sound has been recorded in the Bay of Fundy, Canada from both lone whales (N=9) and social SAGs (N=49). Those lone whales producing gunshot sounds whose sex could be determined (N=9) were all mature males. In surface active groups, the rate of production of gunshot sounds was weakly correlated with the total number of males present in the group. Given the behavioral contexts of gunshot sound production by male whales, gunshots probably function in a reproductive context as an agonistic signal directed toward other males, an advertisement signal to attract females, or a combination of the two functions.