Animal Duets: Forcing a Mate to be Attentive

An animal duet is a joint signaling performance, usually vocal and loud, produced by mates. The initiator of a duet can test its mateʹs commitment if the responses elicited are costly. In addition, the initiator may be able to force its mate to stay nearby, ready to respond. It is suggested that the latter effect exploits the vulnerability of both males and females to competitors. Either mate can initiate a duet. A reply shows that the initiator is paired, and the delay before the reply reveals how attentive the responder is to its mate. Inattentive mates may be nearby but relatively unresponsive, or may be distant. Distance imposes a delay in replying because sound travels sufficiently slowly in air that the initiatorʹs vocalization will not be heard by its mate for appreciable fractions of a second. If competitors are more likely to intrude upon a pair when one partner is not attentive to the other, then initiating a duet should function as a way of forcing the costly and informative behavior of being closely attentive.