Reactions to fear as a proximate factor in the sociospatial organization of baboon progressions

The objective of this study was to test the hypothesis that fearfulness is a key proximate factor determining the nonrandom order repeatedly reported for baboon troops progressing from one location to another. According to this hypothesis, the most vulnerable troop members, the walking immatures, are expected in most circumstances to be cautious and to keep others between themselves and potential danger. The more confident adults, especially large powerful males, should tend toward the front and rear of progressing troops. The fear hypothesis predicts that in progressions toward a fear source, adult males should be near the front of the troop; on the other hand, when the troop is retreating from a frightening or tense situation, adult males should be found more toward the rear. Progressions of chacma baboons away from the location of a severe fright or in retreat from another troop were compared with other progressions. Adult males tended to be more rearward in these situations. The number of adults of either sex interposed between a fear source and the first walking immature was greater for retreating troops than for others. Some adult males continued to be near the front of the troop when retreating from tense situations.     

Population structure,demography, and dynamics of mountain baboons: An interim report

Counts of 61 baboon troops (Papio cynocephalus ursinus) at four localities in the Drakensberg mountains confirmed earlier reports of a small mean troop size. This troop size of 22.49 animals changed neither with latitude nor elevation. Data from two of the sites suggested that population density increases from south to north, while a working assumption of 2.5 animals/ km² allowed us to set the population size at 7,540 animals, living in 335 troops. Both the adult sex ratio of 2.07 females/male and the immature/ adult female ratio of 1.17 were unaffected by troop size. Repeated counts from nine known troops revealed that the population is at equilibrium. © 1995 Wiley-Liss, Inc.     

Trade-offs in skillacquisition and time allocation among juvenile chacma baboons

We hypothesize that juvenile baboons are less efficient foragers than adult baboons owing to their small size, lower level of knowledge and skill, and/or lesser ability to maintain access to resources. We predict that as resources are more difficult to extract, juvenile baboons will demonstrate lower efficiency than adults will because of their lower levels of experience. In addition, we hypothesize that juvenile baboons will be more likely to allocate foraging time to easier-to-extract resources owing to their greater efficiency in acquiring those resources. We use feeding efficiency and time allocation data collected on a wild, free-ranging, non-provisioned population of chacma baboons (Papio hamadryas ursinus) in the Moremi Wildlife Reserve, Okavango Delta, Botswana to test these hypotheses. The major findings of this study are: 1. Juvenile baboons are significantly less efficient foragers than adult baboons primarily for difficult-to-extract resources. We propose that this age-dependent variation in efficiency is due to differences in memory and other cognitive functions related to locating food resources, as is indicated by the greater amount of time juvenile baboons spend searching for food. There is no evidence that smaller body size or competitive disruption influences the differences in return rates found between adult and juvenile baboons in this study. 2. An individual baboon’s feeding efficiency for a given resource can be used to predict the duration of its foraging bouts for that resource. These results contribute both to our understanding of the ontogeny of behavioral development in nonhuman primates, especially regarding foraging ability, and to current debate within the field of human behavioral ecology regarding the evolution of the juvenile period in primates and humans. Sara E. Johnson is Assistant Professor of Anthropology at California State University, Fullerton. She received her Ph.D. in Anthropology (Human Evolutionary Ecology) from the University of New Mexico in 2001. She uses behavioral ecology and life history theory to address her research interests in the evolution of primate and human growth; ecological variation and phenotypic plasticity in growth and development; ecological variation in life course trajectories, including fertility, health, morbidity, and mortality differentials; food acquisition and production related to nutrition; societal transofmration and roles of the elderly among indigenous peoples; and women’s reproductive and productive roles in both traditional and nontraditional societies. For the past decade she has conducted research on these issues in several different populations, including chacma baboons in the Okavango Delta of Botswana, two multiethnic communities of forager/agropastoralists in the Okavango Delta of Botswana, and among New Mexican men. John Bock is Associate Professor of Anthropology at California State University at Fullerton and is Associate Editor of Human Nature. He received a Ph.D. in Anthropology (Human Evolutionary EcologY) from the University of New Mexico in 1995, and from 1995 to 1998 was an Andrew W. Mellon Foundation postdoctoral fellow in demography and epidemiology at the National Centre for Epidemiology and Population Health at Australian National University. His recent research has focused on applying life history theory to understanding the evolution of the primate and human juvenile period. Bock has been conducting research among the Okavango Delta peoples of Botswana since 1992, and his current research there is an examination of child development and family demography in relation to socioecology and the HIV/AIDS epidemic. Other research is focused on health disparties among minorities and indigenous peoples in Botswana and the United States related to differential access to health care.     

The glomerular filtration rate,effective renal plasma flow,and renal blood flow in the adult male chacma baboon (Papio ursinus)

Abstract: The radionuclide determination of glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) has been validated in man, but not in the primate. GFR, ERPF, and renal blood flow (RBF) were measured in a group of 12 adult male chacma baboons using radiopharmaceuticals. GFR was determined using ^99mtechnetium-labelled diethylenetriamine-pentacetic acid. ERPF was measured with ¹³¹iodine-labelled hippuran. RBF, body surface area, and kidney weights were calculated using standard formulae. GFR was 49 ± 11 ml/min and ERPF was 237.9 ± 54.2 ml/min. Calculated RBF was 430.7 ± 111.9 ml/min and 507.4 ± 138.4 ml/min/100g of renal tissue. The results are in agreement with those obtained using more laborious nonradioisotopic techniques such as para-aminohippurate (PAH) and creatinine clearance and could serve as baseline normal values in the adult male chacma baboon.     

Social relationships of mountain baboons: Leadership and affiliation in a non-female-bonded monkey

Instead of close and differentiated relationship among adult females, the accepted norm for savanna baboons, groups of Drakensberg mountain baboons (Papio ursinus) showed strong affiliation of females towards a single male. The same male was usually the decision-making animal in controlling group movements. Lactating or pregnant females focused their grooming on this “leader” male, producing a radially patterned sociogram, as in the desert baboon (P. hamadryas); the leader male supported young animals in the group against aggression and protected them against external threats. Unlike typical savanna baboons, these mountain baboons rarely displayed approach-retreat or triadic interactions, and entirely lacked coalitions among adult females. Both groups studied were reproductively one-male; male-female relationships in one were like those in a unit of hamadryas male at his peak, while the other group resembled the unit of an old hamadryas male, who still led the group, with a male follower starting to build up a new unit and already monoplizing mating. In their mountain environment, where the low population density suggests conditions as harsh for baboons as in deserts, adults in these groups kept unusually large distances apart during ranging; kin tended to range apart, and spacing of adults was greatest at the end of the dry, winter season. These facts support the hypothesis that sparse food is responsible for convergence with hamadryas social organization. It is suggested that all baboons, though matrilocal, are better categorized as “cross-sex-bonded” than “female bonded”.     

Fishing baboons at desert waterholes

Live fish capture by wild chacma baboons is described. Fish were captured from drying desert pools and then covered with sand to immobilize active fish or to facilitate handling. Possible reasons omnivorous primates elsewhere do not capture live fish are considered.     

Peripheral oxytocin in female baboons relates to estrous state and maintenance of sexual consortships

The neuro-hypophysial hormone oxytocin (OT) has been implicated in female reproductive and maternal behaviors and in the formation of pair bonds in monogamous species. Here we measure variation in urinary OT concentrations in relation to reproductive biology and socio-sexual behavior in a promiscuously breeding species, the chacma baboon (Papio hamadryas ursinus). Subjects were members of a habituated group of baboons in the Okavango Delta, Botswana. We collected behavioral data and urine samples from n = 13 cycling females across their estrous cycles and during and outside short-term, exclusive sexual consortships. Samples were analyzed via enzyme immunoassay (EIA) and we used linear mixed models (LMM) to explore the relationship between peripheral OT and a female's estrous stage and consortship status, her previous reproductive experience and fertility. We also used a Pearson's correlation to examine the relationship between OT concentrations of consorting females and their extent of behavioral coordination with their consort partners. The results of the LMM indicate that only estrous stage had a significant influence on OT levels. Females had higher OT levels during their periovulatory period than during other stages of their estrous cycle. There were no differences in the OT levels between consorting and non-consorting periovulatory females. However, among consorting females, there was a significant positive relationship between urinary OT levels and the maintenance of close proximity between consort partners. Our results suggest that physiological and behavioral changes associated with the initiation and maintenance of short-term inter-sexual relationships in baboons correspond with changes in peripheral OT.     

Factors Affecting Reproduction and Mortality Among Baboons in the Okavango Delta,Botswana

We present results of a 10-year study of free-ranging gray-footed chacma baboons (Papio ursinus griseipes) in the Okavango Delta of Botswana. The majority of deaths among adult females and juveniles were due to predation, while infants were more likely to die of infanticide. There were strong seasonal effects on birth and mortality, with the majority of conceptions occurring during the period of highest rainfall. Mortality due to predation and infanticide was highest during the 3-mo period when flooding was at its peak, when the group was more scattered and constrained to move along predictable routes. The reproductive parameters most likely to be associated with superior competitive ability—interbirth interval and infant growth rates—conferred a slight fitness advantage on high-ranking females. However, it was counterbalanced by the effects of infanticide and predation. Infanticide affected high- and low-ranking females more than middle-ranking females, while predation affected females of all ranks relatively equally. As a result, there were few rank-related differences in estimated female lifetime reproductive success.     

4. ONE YEAR'S CENSUS AND STUDY OF BIRDS IN 2½ ACRES OF ALEANY BUSHVELD. (Part 2.) April, 1945, to March, 1946

Hooded Vultures Necrosyrtes monachus are critically endangered but little is known of their year-round use of nests or whether other species usurp Hooded Vulture nest sites. We investigated visitation rates by Hooded Vultures and other species (including potential nest predators and usurpers) to examine their effect on Hooded Vulture breeding success. We present observations of 33 species recorded by camera traps at 12 Hooded Vulture nests over a total of 93 nest-months (2 095 nest-days). Several pairs of Hooded Vultures visited their nests regularly during the non-breeding season, some adding nesting material, highlighting that pairs visited their nest(s) year round. Egyptian Geese Alopochen aegyptiaca, potential usurpers of raptor nests, were present at occupied and unoccupied Hooded Vulture nests, but we recorded no usurpation of nests by Egyptian Geese and they had no impact on vulture breeding success. Hooded Vulture breeding failure was linked to two species only: camera-trap imagery recorded one case of predation of a vulture egg by a Chacma Baboon Papio ursinus, and one case of a Martial Eagle Polemaetus bellicosus predating a vulture nestling. We recommend expanding the Hooded Vulture nest monitoring programme to include more pairs.     

The ecology of motherhood: the structuring of lactation costs by chacma baboons

1. Data from a long-term study of Papio hamadryas ursinus (L.) in the De Hoop Nature Reserve, Western Cape, South Africa, were used to test the assumptions and predictions of Altmann's model of maternal time budgets. 2. Female baboons' feeding time was below model predictions, and there was no evidence for a consistent increase in feeding time with infant age. In addition, female feeding time was not significantly higher than observed baseline feeding times for nonlactating females. 3. Female baboons reduced activity levels in the first few months post-partum, as reflected in significant increases in resting time, and there was some indication that females lost body mass over the course of lactation. When feeding demand was high, females sacrificed social time, and conserved resting time. 4. Females increased vigilance levels during the first 4 months of infant life and were more vigilant overall during lactation than when nonlactating. There was a negative relationship between feeding time and vigilance, but a positive relationship between resting time and vigilance. 5. Female baboons at De Hoop appear to cope with the energetic costs of lactation by reducing activity levels, although this cannot compensate completely for increased energetic costs. This may not be so much an'energy-sparing' strategy as a response to threats presented by infanticidal males in this population. Females therefore trade-off feeding time against vigilance.     

Diurnal variations in serum testosterone concentrations of captive adult male chacma baboons (Papio ursinus)

Captive adult male chacma baboons (Papio ursinus) housed with natural lighting exposure and blood sampled at 3-hr intervals showed significant diurnal variations in serum testosterone concentrations. Low mean concentrations were found at 0800 hr approximately 1 hr after sunrise and mean concentrations were their highest at 2000 hr approximately 1 ¼ hr after sunset.     

Contextual Factors Meditating Contests Between Male Chacma Baboons in Botswana: Effects of Food,Friends and Females

We examined aggressive displays among male chacma baboons (Papio ursinus) over a 23-mo period in the Okavango Delta of Botswana. High-ranking males were more likely than middle- or low-ranking males to participate in displays. Regardless of rank, all males were more likely to participate in chases or physical fights if their opponents rank was similar to their own. Most chases and fights, including those that led to injuries, were also between similarly-ranked males. The rate of both aggressive displays and approach-retreat interactions increased in the weeks before rank reversals, suggesting that rank challenges were preceded by a period when males assessed each others competitive ability and/or motivation. Aggressive displays between disparately-ranked opponents occurred most frequently in contests involving resources of high fitness value: the defense of meat, the defense of estrous females, and the protection of infants against infanticidal attacks. Silent displays were more likely to occur in these three contexts than were displays that occurred as part of more slowly escalating interactions, in which opponents first exchanged calls. Results suggest that competitive encounters among male baboons follow patterns predicted by evolutionary game theory.