Russian scientists have discovered that the roar of marals reveals their status and individuality.

The study was published in the Journal of Zoology. Mating calls are crucial elements of intraspecific interactions that help male red deer attract females (often in groups) and deter other males, playing an essential role during the breeding season. In nature, competition for the right to possess a harem (a group of females) is intense, leading male ungulates to develop complex strategies that include both physical displays of strength and acoustic signals.

Acoustic displays are particularly effective over long distances and even in poor visibility conditions, such as at night when most interactions among deer occur. It is these mating calls that enable females to assess the status and quality of a male from afar, while rivals can gauge whether to engage in competition.

According to the study's findings, the mating call can serve as a kind of "passport" reflecting a male's status. Compared to peripheral males who stay on the outskirts of the harem, harem-holding males produce shorter mating calls with a higher minimum fundamental frequency.

The fundamental frequency of sound is a parameter that is subjectively perceived as pitch and can encompass several measurements: minimum, maximum, initial, and final fundamental frequency. Moreover, even within a single male, these sound parameters change with status: when a male gains a harem, his initial and maximum fundamental frequencies decrease, while his minimum fundamental frequency increases, resulting in shorter sounds.

Although mating calls can reflect status and change with shifts in a male's social standing, their individual characteristics typically remain consistent. It was previously believed that each deer possesses unique acoustic traits, akin to an acoustic "signature," allowing it to be distinguished from other males. This presumed high degree of individual sound differentiation is still utilized in reserves when counting deer by ear, where a trained observer from a single point (listening post) determines the number of deer nearby based on the differences in their calls.

According to one of the study's authors, Associate Professor Olga Sibiryakova from the Faculty of Biology and Biotechnology at HSE University, while individuality in mating calls is evident, it does not always manifest sufficiently well. Zoologists were able to accurately identify the individual origin of 53.2 percent of the sounds, which undoubtedly exceeds random chance, but indicates that it is not always possible to determine the individuality of a specific individual. Notably, status was correctly identified in 78.9 percent of mating calls.

“Deer vocalizations can convey information not only about the individual identity of the caller but also about their status, with status information being expressed in the sounds much more clearly than individuality, which may suggest the greater importance of conveying status information to others during the breeding period,” the researcher notes.

The study's results could be applied in working with deer in natural settings, in deer population assessments that are important for conservation and hunting management activities, as well as in developing non-invasive methods for studying ungulates. The use of non-invasive monitoring techniques can ease the work of zoologists and ecologists, allowing them to track the status and behavior of deer in various conditions without interfering with their natural habitat.