Bioacoustics of Procavia capensis

Movements, Home range and Social organization. Rock Hyraxes are gregarious,living in cohesive and stable family groups or colonies numbering as many as 80 individuals and consisting of 3-7 related adult females, one adult territorial male, dispersing males, subadult females, and juveniles of both sexes. Their numbers vary depending on the size of the kopje. Smaller kopjes or rocky outcrops support only a single colony, but larger kopjes may support several family groups, each occupying a traditional range. There are four classes of mature male: territorial, peripheral, and early and late dispersers. Territorial males are the most dominant, and repel all intruding males from an area largely encompassing the females’ core area. Their aggressive behavior towards other adult males escalates particularly in the mating season, when they monopolize all receptive females. On small kopjes, peripheral males are unable to settle, but on large kopjes they can occupy areas on the periphery ofthe territorial males’ territories. Males are solitary, and the highest ranking among them takes over a female group whenever a territorial male disappears; some studies have reported regular replacement of the dominant male. The females’ home ranges are not defended and may overlap. Rarely, an adult female from outside a group will be incorporated into the family group. The majority ofjuvenile males—the early dispersers—leave their birth sites at 16-24 months old, soon after reaching sexual maturity. The late dispersers leave a year later, but before they are 30 months old. Individual Rock Hyraxes have been observed to disperse over a distance of at least 2 km , although gene flow over distances greater than 10 km is unlikely. The farther a dispersing animal has to travel across open country, where there is little cover and few hiding places, the greater its chances of dying, either through predation or as a result ofits inability to cope with temperature stress. Observers in southern Africa reported shorter dispersal distances, indicating that the rocky habitat and the intervening vegetation between habitat islands strongly influence dispersal distance. Some of the resting time is spent self-grooming, using the lower incisors and the curved claw on the second digit. Grooming and dust bathing help rid Rock Hyraxes of ectoparasites. Rock Hyraxes urinate and defecate in latrines; over time, calcium carbonate in their urine crystallizes, forming deposits that whiten the cliff faces below latrines. Although Rock Hyraxes are gregarious, low levels of intraspecific aggression play an important role in maintaining colonial life. Visual communications include flaring the hairs surrounding the dorsal gland and appeasement behavior. Pilo-erection of the dorsal spot can either signal alarm (if the hairs are erected at a 45° angle) or threat (90°). These clear signals and stereotypical appeasement behavior limit serious aggressive encounters between individuals; agonistic behavior is mostly observed between males during the breeding season. Olfactory communication functions during reproduction and to establish mother—infant bonds. In southern Africa 21 vocal and four non-vocal sounds were recorded. The multitude of grunts, growls, snarls, spits, snorts, and squeals are used in a variety of contexts, but most commonly in showing aggression, appeasement, or defensive retreat. The alarm call in the form of a sharp bark is characteristic and differs from that of the Bush Hyrax and tree hyraxes. The alarm calls used by the sentinels, especially during group feeding, appear to be specific to the particular threat. A repetitious bark or song appears to function in transmitting territorial and sexual signals. Observations in Israel have shown that these songs provide accurate information regarding body weight, size and condition, social status, and hormonal state of the caller. Resident males and some bachelor males sing complex songs in individually distinct voices throughout most of the year, and also countersing with neighboring males. Singing males differ from the general adult male population in that their cortisol levels are higher than those of silent males. In singers, cortisol levels are associated with social rank, with dominants showing the highest levels. Singers are also on average older and more dominant, and they copulate more often than non-singers, suggesting that singing males may have higher reproductive success. Males are more vocal during the breeding season and also use dorsal gland secretions for signalling. These displays may be composed of components that are important in male-male competition, as well as mate choice. The dominantterritorial males monitor urine deposits routinely in search of receptive females. Most copulations are between the territorial males and adult females; peripheral males most often mate with subadult females. However, females mate with more than one territorial male and with peripheral males. Receptive females approach the dominant male and signal their readiness to mate by flaring their dorsal spot hairs, sniffing the male’s anogenital region, and presenting their hindquarters. Males initiate mating through a mating call, weaving head movements, and dorsal spot flaring. Copulations are brief. The young are born inside the rock crevices. Juveniles form nursery groups that often engage in social play; both juveniles and subadults have a much larger area of activity compared with the territorial and peripheral adults. In the Rock Hyrax, a strong correlation was found in females, but not in males, between androgens and cortisol. In most mammal species, the male shows this association. Female and male Rock Hyraxes have similar testosterone levels, and a significant relationship between social status and testosterone levels was observed. These levels differed only between lower-ranking males and females, with lower-ranking females showing higher levels. Dominant females had a significantly lower testosterone level than subordinate females. No association was detected between litter size and a female’s rank, testosterone, or cortisol levels.