Great Apes Scholarly Article: Bonobos
https://royalsocietypublishing.org/doi/full/10.1098/rsbl.2010.1227
In this research paper, the authors investigated “copulation calls” in female bonobos. Female bonobos will make copulation calls to indicate that they are ready to mate. However, female bonobos will inhibit calling when there is a higher ranked female nearby to prevent female competition. Females will have sexual interactions with each other called “genital contacts”. Sounds are less common but they are indistinguishable from copulation calls. After their experiment, the authors concluded that copulation calls have undergone an evolutionary transition from a purely reproductive to a more general social function.
Resource:
Clay, Z. Pika, S., Gruber, T., & Zuberbühler, K. (2010). Female Bonobos Use Copulation Calls as Social Signals. Biology Letters, 7(4).