Testicular Size,Mating System,and Maturation Schedules in Wild Anubis and Hamadryas Baboons

We report body mass and testicular size in 258 anubis (Papio anubis or P. hamadryas anubis) and 59 hamadryas (P. hamadryas or P. h. hamadryas) baboons, live-trapped in Ethiopia. As predicted by theories of sexual selection by sperm competition, among hamadryas baboons, which are monandrous, fully adult males have absolutely and relatively smaller testes than those of comparable males among anubis baboons, which are polyandrous. Male hamadryas are also ca. 10% smaller in bodily mass as adults. The intertaxonal difference in adults is due entirely to the fact that in male anubis baboons, testicular and bodily mass continue to grow up to full adulthood–the age at which most males emigrate from their natal troop and initiate a confrontational breeding strategy among unrelated animals. By contrast, male hamadryas baboons, which are usually philopatric, attain adult body mass and testicular size as subadults. In both species, juveniles experience rapid testicular growth peaking in rate at ca. 12kg body mass, but testicular descent and growth starts earlier in hamadryas than in anubis baboons. Juvenile hamadryas baboons have relatively larger testes than their anubis equivalents, perhaps because male philopatry allows the mating strategy of male hamadryas baboons to be initiated during juvenile life and therefore permits some sperm competition between juveniles and adults.     

Positional behavior of Pan troglodytes in the Mahale Mountains and Gombe Stream National Parks, Tanzania.

The positional behavior of habituated adult chimpanzees and baboons was observed for 784 hr in a year-long study. Comparisons between species were made to establish the distinctiveness of chimpanzee positional behavior and habitat use. Brachiation (sensu stricto, i.e., hand-over-hand suspensory locomotion) was observed in low frequencies among chimpanzees, and its significance for chimpanzee anatomy is judged slight. Although no significant differences were found between sympatric baboons and chimpanzees in the proportion of time spent in the terminal branches, or in the mean diameter of weight-bearing strata, chimpanzees exhibited evidence of a terminal branch adaptation in that they, unlike baboons, used postures among smaller supporting strata different from those used among larger supports. Among chimpanzees, unimanual arm-hanging was most common among the smallest strata and was associated with smaller mean and median support diameter than other postures. Unimanual arm-hanging was the only common behavior among chimpanzees that usually involved complete abduction of the humerus. A number of behaviors often subsumed under the label "quadrumanous climbing" were distinguished in this study. Compared to baboons and other cercopithecoids, chimpanzees did not show increased frequencies of large-stratum vertical climbing, and their vertical climbing did not involve significant humeral abduction. Arm-hanging (i.e., unimanual suspension) and vertical climbing distinguish chimpanzee positional behavior from that of monkeys.     

Primate abundance along five transect lines at Ngogo, Kibale National Park, Uganda

Using the line transect methods, I studied the primate density at Ngogo, Kibale National Park, Uganda for 18 months. Comparisons with other studies show that the population of red colobus monkeys (Procolobus rufomitratus) and blue monkeys (Cercopithecus mitis) is declining, whereas the populations of black-and-white colobus (Colobus guereza), red-tailed monkeys (Cercopithecus ascanius), grey-cheeked mangabeys (Lophocebus albigena), baboons (Papio anubis), and chimpanzees (Pan troglodytes) remain constant or slightly increase. In this paper, I compare data on density from this study to data from previous and recent censuses at Ngogo and with data from other sites in the Kibale forest to examine the stability of primate populations. Furthermore, I test the hypothesis that the changes in red colobus and blue monkey density are due to changes in the forest structure and abundance of their most selected feeding trees, and show that changes in forest composition cannot account for changes in their red colobus abundance, but that hunting by chimpanzees provides a reasonable explanation.     

High Prevalence of Simian T-Lymphotropic Virus Type L in Wild Ethiopian Baboons

Simian T-cell leukemia viruses (STLVs) are the simian counterparts of human T-cell leukemia viruses (HTLVs). A novel, divergent type of STLV (STLV-L) from captive baboons was reported in 1994, but its natural prevalence remained unclear. We investigated the prevalence of STLV-L in 519 blood samples from wild-living nonhuman primates in Ethiopia. Seropositive monkeys having cross-reactive antibodies against HTLV were found among 22 out of 40 hamadryas baboons, 8 of 96 anubis baboons, 24 of 50 baboons that are hybrids between hamadryas and anubis baboons, and 41 of 177 grivet monkeys, but not in 156 gelada baboons. A Western blotting assay showed that sera obtained from seropositive hamadryas and hybrid baboons exhibited STLV-L-like reactivity. A PCR assay successfully amplified STLV sequences, which were subsequently sequenced and confirmed as being closely related to STLV-L. Surprisingly, further PCR showed that nearly half of the hamadryas (20 out of 40) and hybrid (19 out of 50) baboons had STLV-L DNA sequences. In contrast, most of the seropositive anubis baboons and grivet monkeys carried typical STLV-1 but not STLV-L. These observations demonstrate that STLV-L naturally prevails among hamadryas and hybrid baboons at significantly high rates. STLV-1 and -2, the close relative of STLV-L, are believed to have jumped across simian-human barriers, which resulted in widespread infection of HTLV-1 and -2. Further studies are required to know if STLV-L is spreading into human populations.     

The order of movement of yellow baboons (Papio cynocephalus).

The spatial organization of progressing baboons is thought to serve a protective function considered important in their adaptation to a terrestrial existence. Progression positions of identified black infants, adult males, and other yellow baboons were determined from repeated samples of troop movements. Spatial positioning by demographic class was similar to that previously found for three troops of anubis baboons living in two different habitats. Such consistency across species and habitats seems unlikely unless it arises from a common genetic background or common ontogenetic stabilizing mechanism.     

Rates of predation on mammals by gombe chimpanzees, 1972–1975

Rates of chimpanzee predation on mammals are calculated using data on 75 kills recorded during focal observation in Gombe National Park, Tanzania, from January 1972 to April 1975. The chimpanzees were members of two study communities (Kanyawara, or Northern, and Kahama, or Southern, community), and were observed as focal individuals for 14,583 hr by more than 30 researchers and field assistants working in pairs. The rate of predation by females was too low to allow reasonable estimates. For males, the mean rate of killing during the study period was 0.31 kills per male per 100 hr (N=17 males), or 4.65 kills per 100 hr in the two communities. In contrast to results from Mahale Mountains, there was no difference in predation rate between wet and dry seasons. However, predation rates varied over time, increasing by four times between the first three and last four seasons of the sample period. In an average year the 15 adult and subadult male chimpanzees are calculated to have killed 204 prey per year in an area of 16 km², varying between 99 and 420 prey per year in periods of low and high predation rate. Red colobus were the most frequent prey, followed by bushpig and bushbuck. Predation rates varied greatly on different prey species, and were not related to either the proportion of time spent within 200 m of male chimpanzees, or to their population densities. In relation to encounter rates and population density, baboons, blue monkeys, and redtail monkeys were killed at a fraction of the rate of red colobus monkeys, which suffered severe mortality from chimpanzee predation. Predation on bushpig and bushbuck also appears to have been high in relation to population density. The amount of food provided by predation is estimated to have averaged 600 kg per year for chimpanzees in the two communities (totalling 14–17 adult or subadult males, 18–20 adult of subadult females, and about 19 infants or juveniles). This suggests that adult males consumed around 25 kg of meat per year, although any average figure undoubtedly masks considerable individual variation. Present data suggest that chimpanzees in Gombe and Tai National Park, Ivory Coast, prey on mammals at rates higher than other populations.     

Adolescent exaggeration in female catarrhine primates

Adolescent females of 11 primate species display exaggerated versions of the cues to sexual cycle state or fertility which are displayed by adult females: anubis baboons; geladas; Assamese, Barbary, crab-eating, Japanese, and stump-tailed macaques; patas monkeys; gorillas; and humans. These cases are briefly described and a variety of hypotheses is presented and evaluated to account for the adolescent exaggeration. Such exaggeration may be a super-normal sexual stimulus, a barrier to cross-species hybridization, a helpful prop in female:female competition, a passport for transfers, an insurance policy where unpredictable changes of circumstance are likely, or a non-adaptive side-effect of some other phenomenon. The transfer and unpredictability hypotheses seem to apply to the largest number of species, including humans.     

Fetal and infant head circumference sexual dimorphism in primates

Studies have shown that after controlling for the effects of body size on brain size, the brains of adult humans, rhesus monkeys, and chimpanzees differ in relative size, where males have a greater volume of cerebral tissue than females. We assess whether head circumference sexual dimorphism is present during early development by evaluating sex differences in relative head circumference in living fetuses and infants within the first year of life. Head circumference is used as a proxy for brain size in the fetus and infant. Femur length is used as a proxy for body length in the fetus. Ultrasonography was used to obtain fetal measures, and anthropometry was used to obtain postnatal measures in humans, rhesus monkeys, baboons, and common marmosets. We show that statistically significant but low levels of head circumference sexual dimorphism are present in humans, rhesus monkeys, and baboons in early life. On average, males have head circumferences about 2% larger than females of comparable femur/body length in humans, rhesus monkeys, and baboons. No evidence for head circumference sexual dimorphism in the common marmoset was found. Dimorphism was present across all body size ranges. We suggest that head circumference sexual dimorphism emerges largely postnatally and increases throughout maturation, particularly in humans who reach adult dimorphism values greater than the monkeys. We suggest that brain dimorphism is not likely to impose an additional energetic burden to the gestating or lactating mother. Finally, some of the problems with ascribing functional significance to brain size sexual dimorphism are discussed, and the energetic implications for brain size sexual dimorphism in infancy are assessed.     

Hepatitis A and B: serologic survey of human and nonhuman primate sera

Sera of humans and seven species of nonhuman primates were tested by radioimmunoassay and enzyme immunoassay for the presence of hepatitis A antibody, hepatitis B surface antigen and antibody to hepatitis B surface antigen. The outcome of testing a total of 276 serum or plasma specimens was as follows: with the exception of squirrel monkeys (0%) and cotton-top marmosets (0%), a considerable percentage of all other species tested had detectable antibodies to hepatitis A virus: humans 45.9%, chimpanzees 36.6%, baboons 38.2%, vervets 57.9%, cebus monkeys 40.0% and common marmosets 50.0%. Only one human and two chimpanzees were carriers of hepatitis B surface antigen. Antibodies to hepatitis B surface antigen were detected in human (11.3%), chimpanzees (29.9%), baboons (36.2%) and squirrel monkeys (5%). Chimpanzees showed an increasing prevalence of antibodies to hepatitis A virus and hepatitis B surface antigen with age.     

Fibrinopeptides A and B of baboons (Papio anubis, Papio hamadryas, and Theropithecus gelada): their amino acid sequences and evolutionary rates and a molecular phylogeny for the baboons

Amino acid sequences of fibrinopeptides A and B from savanna baboons, Papio anubis and Papio hamadryas, and highland baboon, Theropithecus gelada, were established. The sequences of the fibrinopeptides A from the three baboons were identical: (sequence: see text) The fibrinopeptides B were composed of 9 residues and demonstrated the sequence: (sequence see text) where X3 = Arg in P. anubis, His in P. hamadryas, and Gly in Th. gelada. Position-3 of the B peptides was the only replacement site observed among the 25 amino acid residues in both fibrinopeptides from the baboons. Based on these sequences, a molecular phylogeny for the three species of baboons was deduced. The evolutionary rates of the peptides B of the baboons and macaques were also estimated. It was observed that the fibrinopeptides changed at an uneven rate during the evolution of old-world monkeys, i.e., baboons and macaques.     

Genital Ureaplasmas in nonhuman primates.

Ureaplasmas were isolated from the genital tracts of four of 22 (18.4%) male chimpanzees and eight of 23 (34.8%) female chimpanzees. Twenty-nine female rhesus monkeys, 38 female baboons, one gibbon, and black ape and one Java monkey were shown to be free of genital Ureaplasmas. The rate of reproductive failure among the chimpanzees was high and it is suggested that Ureaplasma may be responsible in part. The chimpanzee may serve as a useful model for human Ureaplasma genital infections.     

Parasitology of five primates in Mahale Mountains National Park, Tanzania

Parasitological surveillance in primates has been performed using coprological observation and identification of specimens from chimpanzees (Pan troglodytes schweinfurthii) in Mahale Mountains National Park, Tanzania (Mahale). In this study, we conducted coprological surveillance to identify the fauna of parasite infection in five primate species in Mahale: red colobus (Procolobus badius tephrosceles), red-tailed monkeys (Cercopithecus ascanius schmidti), vervet monkeys (Cercopithecus aethiops pygerythrus), yellow baboons (Papio cynocephalus), and chimpanzees. Fecal samples were examined microscopically, and parasite identification was based on the morphology of cysts, eggs, larvae, and adult worms. Three nematodes (Oesophagostomum spp., Strongyloides sp., and Trichuris sp.), Entamoeba coli, and Entamoeba spp. were found in all five primate species. The following infections were identified: Bertiella studeri was found in chimpanzees and yellow baboons; Balantidium coli was found in yellow baboons; three nematodes (Streptopharagus, Primasubulura, an undetermined genus of Spirurina) and Dicrocoeliidae gen. sp. were found in red-tailed monkeys, vervet monkeys, and yellow baboons; Chitwoodspirura sp. was newly identified in red colobus and red-tailed monkeys; Probstmayria gombensis and Troglocorys cava were newly identified in chimpanzees, together with Troglodytella abrassarti; and Enterobius sp. was newly identified in red colobus. The parasitological data reported for red colobus, vervet monkeys, and yellow baboons in Mahale are the first reports for these species.     

Prevalence of Babesia microti in free-ranging baboons and African green monkeys

Babesia microti-like parasites have been reported to infect captive non-human primates (NHPs). However, studies on the prevalence of Babesia spp. in free-ranging NHPs are lacking. This investigation aimed at determining the prevalence of B. microti in wild-caught Kenyan NHPs. In total, 125 animals were studied, including 65 olive baboons (Papio cynocephalus anubis) and 60 African green monkeys ([AGMs] Chlorocebus aethiops). Nested polymerase chain reaction targeting Babesia β-tubulin genes was used to diagnose infection prevalence. Results indicated a prevalence of 22% (27/125) B. microti infection in free-ranging NHPs in Kenya. There was no statistically significant difference in B. microti infection prevalence between baboons and AGMs or male and female animals. This is the first report of the presence and prevalence of B. microti in free-ranging Kenyan NHPs.     

Hierarchy and social status in Budongo chimpanzees

The status hierarchy is fundamental in the lives of male chimpanzees. This study describes the dominance interactions and social status among adult male chimpanzees of the Sonso community in the Budongo Forest Reserve, Uganda, during the period that they were first studied (1994 and 1995). Social dominance is typically measured using the behaviour of either the subordinate or the dominant individual, but a relationship is dependent on the behaviour of both parties and this study explicitly used both subordinate and dominant behaviours to investigate the status hierarchy. Among adult males of the Sonso community, agonistic interactions occurred at a low rate and pant-grunts were rare, but males could be ranked into separate hierarchies of agonistic dominance and pant-grunting (labelled respect) using ratios of behaviour performed/behaviour received. These hierarchies were combined to form a single hierarchy of social status that divided the males among five distinct status levels. The highest status level was held by an alliance between two males who replaced the previous alpha male during the first part of the study. Neither male in this alliance partnership pant-grunted to the other, although the reason for cooperative behaviour was unclear. Although the nominally beta male was treated as such by other adult males, he achieved surprisingly little mating success. Budongo Forest chimpanzees do not warrant the sometimes-expressed view that they are non-aggressive and peaceable and the broad pattern of their status interactions matches with that seen in other chimpanzee populations.     

Rearing of conventional and gnotobiotic nonhuman primates (Pan troglodytes, Papio cynocephalus, Saguinus nigricollis).

Rearing techniques for conventional and gnotobiotic nonhuman primates are described. Up to four months of age there was no significant difference in weight gain between conventionally and gnotobiotically reared chimpanzees or baboons. After four months, gnotobiotic chimpanzees exceeded their conventional counterparts in weight gain, whereas conventional baboons showed higher weight gain than gnotobiotic baboons. Gnotobiotic chimpanzees and baboons had significantly lower absolute numbers of neutrophils than their conventional counterparts, but the absolute numbers of lymphocytes were not different. The gnotobiotic rearing of marmosets is also reported.     

Alpha status and agonistic alliance in wild chimpanzees (Pan troglodytes schweinfurthii)

Intermale competition was studied in a habituated group of wild chimpanzees (Pan troglodytes schweinfurthii) in the Mahale Mountains of Tanzania. The group of 27 individuals included 3 adult males and 12 adult females. The beta-ranked male was observed to attack the alpha male and usurp his status. The beta male was supported by an ally, the gamma male. Earlier in the competition the gamma male had supported the alpha male. When the alpha male was displaced, he completely lost what had been an exclusive copulatory right. It was clear that alliance with the most subordinate male was a critically effective strategy for the major competitors. The alliance strategy of the gamma male invested him with important power. The strategy of changing alliance is referred to as “allegiance fickleness.” It is suggested that allegiance fickleness could provide a basis for individual selection of social intelligence.     

Neutralizing antibodies to simian papovavirus SA12 in Old World primates in laboratory colonies: high prevalence in baboons

Sera from 517 laboratory-housed nonhuman primates representing five genera and from 13 laboratory workers were examined for the presence of neutralizing antibodies to SA12 virus. The antibody prevalences were as follows: baboons, 66%; patas and vervet monkeys, 24%; macaques, 8%, and chimpanzees, 2%. The serum of one laboratory worker had antibodies. These results suggest that SA12 virus is a common infection of nonhuman primates in laboratory colonies, especially baboons.     

Migration of male hamadryas baboons into anubis groups in the Awash National Park,Ethiopia

Among “savanna” baboons, males are the dispersing sex, and females are philopatric. Despite clear evidence for migration of adult males at Erer-Gota, Ethiopia (Abegglen, 1984), it is generally believed that a different pattern-dispersal only by female transfer-is found in hamadryas baboons,Papio hamadryas hamadryas (Pusey and Packer, 1987; Pusey, 1988; Stammbach, 1987). Since the late 1960's, there have been isolated observations of hamadryas males migrating into anubis groups in the Awash National Park, Ethiopia (Nagel, 1973; Kawai and Sugawara, 1976; Sugawara, 1982). Since 1983, we have observed 11 individually identified adult hamadryas immigrants in four anubis groups above the Awash Falls and have trapped and tagged 9 of them. One subadult male was also captured and marked. Repeated visits to the study site allow us to document long-term residence of these “cross-migrant” males in their host groups. The longest-resident male has been in the same group for 5 years or more; a conservative estimate of the average length of residence is 3 years. We estimate that 25 hamadryas males have moved into this ozne over the last 15 years. Although larger than the hamadryas males captured in 1973, all but one of our cross-migrants appear phenotypically hamadryas. By comparing, the ages of our cross-migrants with Abegglen's account of the typical hamadryas male life-history, we have found that the adult hamadryas males seem to immigrate at ages consistent with having left their     

Predation on mammals by chimpanzees in the montane forest of Kahuzi, Zaire

The rate of predation on mammals by chimpanzees was determined from carcasses and from fecal specimens found on fresh trails during a 16-month period in the montane forest of Kahuzi-Biega National Park, Zaire. A unit-group of semi-habituated chimpanzees, composed of 22 – 23 individuals including 8 adult or adolescent males, appeared to kill about 18 – 30 mammalian prey (16 – 28Cercopithecus monkeys) per year, if the multiple kills by chimpanzees were not considered. A juvenile l'Hoest's monkey was recorded for the first time as the prey of chimpanzees in this study. Predation occurred in the late dry and the early rainy seasons, when the diversity of ripe fruits was the highest during the year. The Kahuzi chimpanzees tended to kill mammals less frequently but to killCercopithecus monkeys more frequently than chimpanzees in other habitats. The absence of red colobus monkeys, which are the most frequent prey in Gombe, Mahale, and Tai, might be responsible for the low predation rate. However, the estimated rate of predation onCercopithecus monkeys is the highest record among various chimpanzee habitats. At least 11 – 18% of theCercopithecus population seemed to be lost annually as a result of being killed by chimpanzees. Chimpanzees may be the most important predators on these monkeys in the absence of leopards at Kahuzi. The examination of fecal samples and carcasses suggested that adult (probably male) or adolescent chimpanzees tended to eat juvenile or subadult monkeys most frequently, as is also seen for chimpanzees in Gombe, Mahale, and Tai.