In mate selection, female white rhinoceros are most likely guided by the unusual vocal calls of males, which can stimulate females into oestrus. This follows from the research of Ivana Cinková from the UP Department of Zoology, Faculty of Science, who studied the vocal manifestations of male rhinos during courtship at the Hluhluwe-iMfolozi Park in South Africa. An article on the courtship “hic” calls of rhinos has been published in the journal Animal Cognition.
“In our research, we were interested in the importance of courtship hic calls of male rhinos and whether they contain any information that may be important for females in choosing their partners. We also monitored how females react to these calls and what information they can obtain from them,” Cinková stated.
Male southern and northern white rhinoceros constantly accompany females in their territory for up to 20 days before their potential partner comes into heat. They try to prevent the female from leaving her territory. During this time, the male approaches the female more often and calls her in a courtship hic calls. “It is a long sequence of wheezing to squeaky sounds. It is very difficult to record them in the wild, because the females only come into oestrus after about two and a half years and soon get pregnant again. Moreover, in zoos, these rhinos reproduce very poorly,” said Cinková.
The rhinos were observed in South African Hluhluwe-iMfolozi Park. “We found that out of all the rhino voices studied in the past, it is the hic calls that most likely determine a male’s individual identity, which can be important information for females when choosing a partner,” the researcher said.
Females in oestrus can gradually move through the territory of six to seven males, while other rhinos, which have lower positions in the hierarchy or have wandered in foreign territory, also often reside in these territories. “Our results thus suggest that females could also select a mate they know well and whose territory they prefer on the basis of hic calls,” said Cinková.
In the park, Cinková played recordings of male calls to adult female rhinos and from their reactions she determined that they recognised the male hic calls from their contact calls. “At the same time, they also distinguished some differences between the hic calls of both southern and northern white rhinoceros,” she said.
Both rhinoceros species are closely related, so some plans to rescue the critically endangered northern white rhinoceros include a variant of interspecies breeding to preserve at least some of their unique genes. “However, the results of our research suggest that differences in hic calls between the two species might potentially lead to a reduction in the likelihood of natural hybridization between southern and northern white rhinoceros,” she added.