For female gelada monkeys, a grunt from a male primate won't suffice to get her attention. The call of the wild must involve moans, wobbles or yawns to entice these females, according to a new University of Michigan study involving the Ethiopian mammals.

In findings appearing in Scientific Reports, U-M researchers found that female geladas who heard recorded playbacks of male vocal sequences containing one of three derived call types—moans, wobbles and yawns—lingered longer and spent more time near the speaker.

Each of these call types are acoustically interesting, the researchers say. Moans are long in duration, wobbles have a high degree of frequency change and yawns use a large frequency bandwidth.

"Females pay more attention to male vocal sequences that contain acoustically elaborate calls," said Morgan Gustison, a doctoral student in the Department of Psychology and the study's lead author. "Not only do the females look longer, but they also choose to hang around the area where they heard an elaborate sequence."

Thore Bergman, a professor of psychology and ecology and evolutionary biology, worked with Gustison on the study.

Read full Michigan News press release and listen to male geladas