individual longevity, meaning that "it is not the number or strength of associations that an adult individual has (i.e. centrality) that is important, but the overall configuration of social relationships within the group." The reason for such a balanced group configuration, rather than one that is centrally dominated by a few individual hyraxes, was suggested to have to do with the fact that information flow to all members is important in a fragmented habitat as that of the hyrax, making a dominance hierarchy a liability for the survival of the group at large. Vocalisations Captive rock hyraxes make more than 20 different noises and vocal signals. The most familiar one is a high trill, given in response to perceived danger. Rock hyrax calls can provide important biological information, such as size, age, social status, body weight, condition, and hormonal state of the caller, as determined by measuring their call length, patterns, complexity, and frequency. More recently, researchers have found rich syntactic structure and geographical variations in the calls of rock hyraxes, a first in the vocalization of mammalian taxa other than primates, cetaceans, and bats. Higher-ranked males tend to sing more often, and the energetic cost of singing is relatively low. A recent study found that snorts, a rare aspect of male hyrax songs, play an important signalling role as well, with increasing snort harshness being associated with "the progression of inner excitement or aggression". It is also positively associated with the singing animal's social status and testosterone levels. Singing has also been shown to be a marker of an individual hyrax's unique identity, where identity is expressed by unique vocal signatures "that are not condition dependent and are stable over years in singers that did not alter their spatial position." Resting The rock hyrax spends roughly 95% of its time resting. During this time, it can often be seen basking in the sun, which sometimes involves "heaping", where several animals pile on top of each other. This is thought to be an element of its complex thermoregulation. Dispersal Male hyraxes have been categorised into four classes: territorial, peripheral, early dispersers, and late dispersers. The territorial males are dominant. Peripheral males are more solitary and sometimes take over a group when the dominant male is missing. Early-dispersing males are juveniles that leave the birth site around 16 to 24 months of age. Late dispersers are also juvenile males, but they