Animal pairs engage in mutual signals by simultaneously performing a diverse repertoire of behaviors. A famous example is the sophisticated dance (mutual displays) performed by bird pairs. In general, previous studies have analyzed individuals separately, thus studies elucidating the complex interactions between two individuals, such as pair dances, have been extremely limited. The emerging property of pair dances cannot be revealed without analyzing the behaviors of both individuals together.
This study focused on the pair dance of wild red-crowned cranes. The pair dance is performed by breeding pairs and lasts up to three minutes. Until now, very little was known about the details of the bidirectional communication during their pair dance.
We observed 21 pairs of wild red-crowned cranes in Kushiro, Hokkaido. The sequence and duration of behavioral elements for both males and females were recorded, and the interplay of dance behavioral elements were analyzed using multiple statistical methods.
Analyses of 99 pair dances revealed that three specific behavioral elements—bill-stab, bow, and arch —characterized the sequence and combinations. This indicated that the pair dance has some rules. Furthermore, the analysis quantifying temporal associations between actions revealed that the behavioral element was sometimes determined by the partner's preceding action, highlighting that timing between pairs is key to the pair dance. These findings clearly demonstrate that the order and timing of behavioral elements play a crucial role in pair communication. In addition, despite the lack of apparent sexual dimorphism in the cranes, several sexual differences were found in the pair dance. Males danced longer than females, and females tended to take the lead in determining the content of the pair dance.
This study quantitatively revealed the complexity of bidirectional communication in pair dances, demonstrating that pairs dance in response to their partners. This finding not only deepens our understanding of crane pair dances but also highlights the importance of considering mutual interactions between two individuals as a unit. Future work will improve this research framework and apply it broadly to other bidirectional communication beyond pair dances. This is expected to enable a detailed understanding of how each animal engages in complex, mutual signals.
