Factors influencing the stability of matrilineal dominance hierarchies were investigated in a feral troop of vervet monkeys (Cercopithecus aethiops sabaeus) in Barbados. Changes in the matrilineal dominance hierarchy were investigated over a 12-year period (1979-1991). Matrilineal ranks remained unchanged for the first 7 years (stable period), reversed on several occasions over the next 3.5 years (unstable period), and have re-stabilised for a further 3.5 years to present date. The frequency distribution of non-matrilineal supports in different social contexts, the lower support frequency in unstable than stable periods, and in particular the high reciprocity evident in non-matrilineal support exchanges, suggest that non-matrilineal support is better explained by reciprocal altruism than by mutualism in vervet monkeys. (Abstract shortened by UMI.)

No description available.

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Two approaches were taken to investigating constraints on kinship in predicting social behaviour in the vervet monkey Cercopithecus aethiops sabaeus in Barbados. in Chapter 1, behavioural interactions between an adult female and an unrelated adopted infant were compared with those between mothers and their natural offspring. The adoptive mother consistently scored higher than mothers with their own offspring in pre-weaning contact-maintaining behaviours, but the difference was not statistically significant. Post-weaning aggression and support interactions between mothers and infants also suggest no difference in parental behaviour and parental costs between adoptive and natural mothers. During post-weaning, the adopted infant was more aggressive to other troop members, and provided more maternal support in aggressive disputes, than another high ranking infant of the same year. / In Chapter 2, effects of kinship on the distribution of aggression and support in feral vervet monkeys were investigated by comparing aggression and support between full sibs and maternal half sibs (within matrilines), and between paternal-half sibs and unrelated juveniles (between matrilines). The strong tendency to behave affiliatively to matrilineal members in Old World monkeys, and maternal control of offspring rank within matrilines, may constrain the ability of offspring to enhance inclusive fitness by behaving differentially to either paternal or maternal sibs based on their degree of relatedness.

I studied free-ranging vervet monkeys (Chlorocebus aethiops) in South Africa using focal animal sampling to test current theories of reproduction and maternal investment. Mothers cope with the energetic costs of lactation by feeding more than non-lactating females and targeting higher nutrient quality items as their infant ages. The dynamic nature of mother-infant interactions is highlighted, with infants spending less time in contact while the mother is moving and foraging. Other troop members “allomother” the infant primarily in the infant’s first couple of months. The length of investment is explored, with greater length of interbirth interval in low nutrient quality environments, larger troop sizes and higher survival rates. Maternal dominance rank and infant sex significantly influenced time in ventral contact, with low-ranking daughters spending more time in contact than high-ranking daughters. The findings from this thesis highlight the complex interaction of ecological and social conditions on maternal investment. / xiv, 182 leaves ; 29 cm

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Vervet monkeys (Chlorocebus pygerythrus) are generally described as a territorial species, though variations in territoriality have been observed. This research examined the impact of high population density, large group sizes and extensively overlapping home ranges on the expression of territoriality in a population of vervet monkeys. Over a period of eighteen months, data were collected on three large troops of vervet monkeys (PTN = 31, RBMN = 39, RSTN = 57) on the Samara Game Reserve, South Africa. I examined the spatial dynamics demonstrated in this population, assed the extent and use of home range overlap and examined the occurrence of intertroop encounters in relation to mate defence, resource defence and home range defence. The home ranges of the troops in this study population overlap substantially, and overlap areas are exploited extensively. The frequency of occurrence of intertroop encounters does not increase in the mating season, nor is there evidence of the defence of particular food patches or home range defence. The findings from this thesis emphasize the importance of examining the expression of territoriality of a population within the context of its environment. / xvi, 125 leaves : ill. ; 29 cm

Self-directed behaviours (SDB) were recorded as a behavioural indicator of arousal in free-ranging vervet monkeys (Chlorocebus aethiops) inhabiting the Klein Karoo of South Africa. Measurement of SDB allowed for changes in arousal to be correlated with particular social situations, potentially providing insight into how monkeys perceive their social world. The research presented here is divided into three core chapters demonstrating that 1) arousal is influenced to a greater extent by degree of association than by hierarchical rank, 2) that an individual‟s level of arousal is influenced by its neighbour‟s spatial location, and 3) that habituated animals that no longer perceive humans as a direct threat nevertheless continue to respond to their presence in other ways. Overall, SDB appears to be a useful, non-invasive, simple means of investigating social arousal and its use has elucidated several key findings regarding the perception of social space and social partners in vervet monkeys. / ix, 103 leaves ; 28 cm

This study explores the effect of changing ecological conditions on female social organization among free-ranging vervet monkeys (Cholorocebus aethiops pygerythrus) in the Klein Karoo, South Africa. Comparison was made between a previous study conducted during a period of drought in 2009, and my own study conducted when conditions were much wetter and hence, less ecologically stressful. In addition, animals in the present study also experienced conditions of low demographic stress. Compared to 2009, females displayed lower rates of competition and aggression, did not compete for access to grooming partners, and did not preferentially groom those of high rank, nor did they do so more frequently. Females did, however, preferentially associate spatially with those they groomed most; a finding in contrast to the previous study. Females did not groom those of adjacent ranks more frequently, nor was there any relationship between rank difference and spatial association. In addition, there were rank differences in vigilance were found between females, and vigilance costs overall were affected by total group size. Overall, these findings support some aspects of the socioecological model used to predict group structure in primates, but other aspects of social organization remain puzzling, and may reflect larger overall group sizes in the Samara population, which changes patterns of engagement between females in ways not fully captured by current models. / xi, 122 leaves ; 29 cm

The permanent coresidence of males within a troop is unusual but occurs in vervet monkeys. Several hypotheses have been projected to explain the coexistence of male vervets (predation risk, breeding season length) but these hypotheses fall short in explaining the multimale nature of vervet monkeys. In order to determine the explanation for coresiding males, I collected male behavioural data from two troops over the course of nine months. My dataset was divided into two categories, male-male interactions and female-male interactions. The male-male data indicate that breeding season is the most active time for migration, aggressions and wounds. Coalitions were described for the first time, and affiliative interactions between males highlighted coping tactics of males in regards to their coexistence. The female-male data indicate there was little indication for distinct male or female choice for mating. Specifically, olfactory information appears to lower successful copulations of males, and female resistance also decreased successful copulations. Grooming was not a commodity traded for mating access. Male dominance was not correlated with mating success, and females seem to express their preference for sexual partners. The large cohort of males of my troops appears to alter behaviours observed at other sites. The maintenance of male-female associations after breeding season suggests that males may be preparing for next breeding season, and males may co-reside for breeding purposes. / xiii, 123 leaves : ill. maps ; 29 cm