Female copulatory vocalizations, also called female copulation calls or coital vocalizations, are produced by female primates, including human females, and female non-primates. Copulatory vocalizations usually occur during copulation and are hence related to sexual activity. Vocalizations that occur before intercourse, for the purpose of attracting mates, are known as mating calls.
In primates, copulation calling is typically observed at the end of mating and there are vast variations between species regarding its occurrence, frequency and form. It is agreed that coital vocalizations fulfill an evolutionary purpose and that they serve as adaptive solutions to problems that the females face, such as infanticide, as well as obtaining high quality sperm.
In non-primates, copulatory calling predominantly occurs before copulation in order to attract mates (mating call). Calls vary in frequency (14 Hz to 70,000 Hz) and function. One of the main purposes of females vocalizing is the induction of mate guarding behavior in males. Conversely, calls may also be used in order to attract high ranking mates who can prevent intercourse with the initial partner. This is done to incite male mate competition.
In humans, coital vocalizations are linked to sexual pleasure or sexual gratification and orgasm, hence occurring during copulation and serving as an expression of sexual pleasure. Vocalizations can be used intentionally by women in order to boost the self-esteem of their partner and to cause quicker ejaculation.
In non-primates
Occurrence
In addition to emitting copulatory vocalizations during and after copulation (as it is mostly seen in primates), non-primate species also vocalize before engaging in mating. Vocalizations that are made prior to copulation are named mating calls. They serve as a means to advertise sexual receptivity and are predominantly used by males to attract female mates. In general, non-primates emit more calls before copulating, as exemplified by the croaks of male frogs and the melodic tweeting of song sparrows.
Properties
In regard to the calling properties, frequency analysis is typically used in research to look at the complexity of the vocalization and to distinguish between calls, which is important in determining their function. Large frequency variations have been noted between species, ranging from 14 Hz to 70,000 Hz. Mice, for instance, use 70,000 Hz calls continuously prior to copulation. They then lower the frequency down to 40,000 Hz during the copulatory act, therefore two qualitatively different calls are used for attracting mates as compared to the actual act of mating. Most of the calling in mice is done by males. They use these ultrasonic calls (> 20,000 Hz and hence not discernible by the human ear) to attract females, with the quantity of calls being related to the male's mating success, making these vocalizations a sexually selected trait.
On the other end of the spectrum, female African elephants use very low frequency calls of 14–35 Hz prior to, as well as during, copulation. Due to their low frequency these calls can be heard for several kilometers and are therefore effective in signalling receptivity. The vocalizations of female elephants are also used in order to incite mate guarding behavior in the male, which manifests itself in the form of fighting off any newly arriving mates. Not only females make use of this, as male Columbian ground squirrels have been observed to use copulatory vocalizations in order to announce their post-copulatory mate guarding to others. In addition to being used to retain the mate via mate guarding induction, female copulatory vocalizations can also be employed to achieve his departure. Red junglefowls, for instance, utilize calls in order to prevent or end unwanted copulations by attracting another high-ranking male fowl. Further effects of female calling on male's behavior are illustrated by spiders that have been shown to stridulate before copulation to inform males of sexual receptivity as well as during intercourse in order to influence male genitalic movements.
Moreover, attracting new mates by calling out during copulation can entail many benefits for the female. Female crickets which mate with multiple partners receive a greater number of nuptial gifts, causing them to lay a larger quantity of eggs, hence increasing their reproductive success.