Social Context Predicts Vocalization Use in the Courtship Behaviors of Weddell Seals (Leptonychotes weddellii): A Case Study

Abstract

Despite previous research, no study has convincingly demonstrated what role if any vocalizations might play in the reproductive behavior of Weddell seals (Leptonychotes weddellii). To better understand that role, we created an artificial territory for an adult, male Weddell seal under the shore-fast ice in McMurdo Sound, Antarctica, and recorded its in situ vocalizations and non-vocal behaviors with an underwater video camera and hydrophone while alone, with another male, and with one or more females. Additionally, we simultaneously recorded the vocalizations and non-vocal behaviors from a female interacting with the male. Analysis of 86 hr of video and audio recordings showed: 1) the male vocalized more than the female, 2) the male’s vocal repertoire was larger than the females’ repertoire, 3) vocalizations changed quantitatively and qualitatively with social context, and 4) patterns of vocalizations and non-vocal behaviors were detected with Theme, pattern recognition software from Noldus Information Technology. These results provided strong evidence that vocalizations played an important role during courtship, and together with the significant behavioral sequences, vocal and non-vocal, they provided insight into the function of their vocalizations including chirps, growls, jaw claps, knocks, mews, trills, and trills + knocks.

Keywords

• Weddell seals
• Leptonychotes weddellii
• Vocalizations
• Courtship
• Resource defense polygyny
• Male-male competition
• Female-mate choice
• Gender specific vocalizations
• Social context