Baboon Babble
- francie saunders
- Aug 17, 2020
- 29 min read
A study of the correlation of communicative behaviors and habitat, sex, and majority troop behavior in Papio anubis
Abstract
As habitat loss and human-wildlife conflict continues globally, countless efforts will be made to protect species whose futures are threatened by the actions and consequences of human life. As the need for conservation grows so does the need to intimately know the natural behaviors, diets, and habitats of species of interest. In Northern Tanzania there exists the village of Mto Wa Mbu that borders Lake Manyara National Park. As the park attracts tourists and profit it also attracts Tanzanians in search of income opportunities. Tourists visit to see the various forms of wildlife for a day or two while tour guides and locals face daily challenges that result from sharing land with wild, African animals. One species that has already experienced great exposure to this tension are the Papio anubis of Mto Wa Mbu. For these reasons I decided to conduct my study on the communicative behaviors of these Olive Baboons. In Mto Wa Mbu I studied the facial expressions and vocalizations of troop members who exited the National Park during the day in relation to sex, habitat, and majority troop behavior for 15 days. Observation took place for 4 hours a day, for a total of 137 scan and 168 focal samples, or 52.1 hours of data collection. Chi-square analyses were run on the dependence of agonistic or affiliative communicative behaviors and sex, habitat, and majority troop behavior (α=0.10). Analysis found that majority troop behaviors (grooming, foraging, resting, moving) were dependent of habitat (p<0.00001). agonistic behaviors were found to be dependent of sex (p=0.02787) while affiliative behaviors were independent of sex (p=0.38277). Both agonistic and affiliative behaviors were found dependent of habitat in which they were performed (p=0.001906, p=0.000926). Analysis also found that agonistic behaviors were dependent of majority troop behavior (p=0.001322) while affiliative were independent of majority troop behavior (p=0.873446). Studying the complex societies and communication that maintains relationships and hierarchies within this species can benefit future efforts to relieve tension between human and wildlife that is prevalent in places like Mto Wa Mbu, Tanzania.
Introduction
Papio anubis, otherwise known as the Olive Baboon, supports its complex social structure within troops and clans through complex methods of communication. With the use of facial expressions and vocalizations members of the species are able to communicate fear, aggression, wariness, intent, and affection. Troops of baboons are comprised of clans containing one alpha male to multiple female, their offspring, and often subadult males that have yet to mature and separate from the group (Estes 1991). agonistic behaviors, those associated with aggression and fighting, play important roles in maintaining the social structure while affiliative behaviors serve to support peaceful group cohesion. A female baboon will remain in the same troop for the duration of her life while a male will emigrate into and between troops. A female baboon’s place in the social hierarchy is determined by 2.5 years after birth (Estes 1991). Not unlike most nonhuman primate species, Papio anubis requires communication and meaningful interactions to allow for their complex social structures and successful inter- and intra-species cooperation within their environment. Interaction occurs not only between conspecifics but also other species, such as humans, with which troops of baboons often come into contact in the village of Mto Wa Mbu, Tanzania.
As the national parks of Tanzania do not utilize any type of physical fencing, both wildlife within and humans outside can cross invisible boundaries that separate the protected area from the surrounding villages and farms. This allows for the troops of Olive Baboons in Lake Manyara National Park of Mto Wa Mbu, amongst other species, to freely exit the park as they do virtually every day. The National Park and consistent tourism throughout the country has enticed Tanzanians to move to the village in search of income from tourism as well as crop cultivation. This has created tension between humans and wildlife.
The Olive Baboon is the most widely distributed African primate. These opportunistic omnivores utilize terrestrial locomotion and are found throughout the African Savannahs where woodlands and water sources present (Estes 1991). The name “Olive Baboon” stems from the olive coloring of the species’ fur. Its dog-like head and snout, terrestrial habitats, and large body size characterize this species. Individuals can grow to weigh up to 50 kilograms and walk on all four limbs of almost equal length. The anatomy of their cranium includes small eyes set close together beneath a prominent brow accompanied by their long, dog-like nose. Sexual dimorphism is prevalent in the species with differences in fur color and body size between males and females. Males vary from a body size weighing on average 23 kilograms while females range from 11 to 12 kilograms (Estes 1991). This size difference can be seen playing a role in the social hierarchy of baboon clans. While females’ rank is determined relatively early on in life, males must maintain dominance in troops and clans not only by means of reproductive success.
Taking advantage of whatever food source is available to them, the Olive Baboon diet can consist of twigs, roots, fruits, flowers, small vertebrates, seeds, nuts, grasses, and other vegetation. Individuals will most often utilize optimal foraging, seeking the most nutritious foods in their habitat. Studies on the species have found that troops spend a majority of their foraging time consuming grasses (Estes 1991). The dew from the grasses serves also as an important source of water for the baboons, which need to drink about every two days. In Mto Wa Mbu, a village that depends on crop cultivation for much of its income, baboons enjoy foraging, or stealing, from the local farms surrounding the park if the opportunity arises.
As the human population of Mto Wa Mbu continues to grow, the nonhuman species that find residence outside and within Lake Manyara National Park boundaries risk further human-wildlife conflict as well as potential loss of habitat. Farmlands and homes will continue to encroach the boundaries of protected areas, surround the parks and threaten the habitat quality and consequently the survival of Olive Baboons. Conflict already exists between resident baboons and villagers who resent the primates’ stealing of crops, the infrequent raiding of homes, or simply the presence of the baboons. Often baboons are threatened if not killed by villagers of Mto Wa Mbu despite the baboons’ rather docile behavior, as I learned from Stanley Darabe, a life-long resident of the village familiar with the issues between humans and baboons. If this conflict persists and action must be taken to protect the species and alleviate the human-wildlife issue, these troops or some members may face time spent in captivity or very close involvement with humans.
Although captivity or human intervention must be utilized for some conservation, rescue, protection or beneficial research efforts, its detrimental effects on animals suggest it should only be used for a brief amount of time in a space that mimics species’ natural environments and allows for essential communication between species members. Studies have found captivity can affect the behavior and genetic composition of individuals if not executed properly (Britt, Welch & Katz, 2003; McDougall, Reale, Sol & Reader, 2005). Changes in behavior and genetic makeup can have damaging effects on the success of conservation efforts and the wellbeing of a species. Nonhuman primates such as Papio anubis have evolved to learn how to identify and avoid predators, locate food, and perform pertinent social behaviors with their conspecifics from the day they are born (McGrew, 1981). Nonhuman primate evolution is in part attributed to the “sophisticated relationship to the environment” that each species creates through activities like foraging and associating with conspecifics (Cunningham & Janson 2007). Learning from other members of the species and successful communication continues throughout an individual’s life and allows for increased chances of survival, complex social relationships, and group cooperation within the environment. Natural behaviors that have evolved to support complex primate societies can become obstructed through the use of captivity or direct human interaction.
Shirley Strum, an expert on Olive Baboons, supports the idea of “baboon social complexity,” that relies on a complex system of communication to be sustained (Strum 2012). Understanding the communication utilized by this species may allow for greater success with any future conservation efforts. Being unable to locate in depth analysis of Olive Baboon communication, I decided to focus this study on the methods of communication observed in the troops of Mto Wa Mbu. Therefore, this study will investigate the communicative behaviors of adult male and female olive baboons in relation to sex, majority troop behavior and habitat while also focusing on the troop as a whole. The focal sampling will follow male and female adult baboons, as these individuals should have a relatively strong understanding of communicative behaviors while subadults may still be mastering these skills. Scan sampling will not distinguish age-class or sex but instead will note strictly the occurrence of any classified behavior observed during sampling.
These communicative behaviors, described in detail in Appendix A and Appendix B, recorded in this study are defined as 8 vocalizations and 7 facial expressions performed by members of the species. Habitat and majority troop behavior are significant correlates in this study. Different habitats provide various conditions with which the species will interact with their environment and may therefore elicit certain behaviors more than others. Therefore I formed my study question: is there a correlation between the communicative behaviors, facial expressions and vocalizations, of Olive Baboons and habitat, majority troop behavior, or sex of an individual? Majority troop behavior may influence the types of communicative behaviors performed as some behaviors may conflict or cooperate with the majority troop behaviors of grooming, moving, resting, and foraging. The sex of an individual may determine whether agonistic or affiliative behaviors are more often observed as a result of the social structure and sexual dimorphism within the species. I hypothesized that the performance of affiliative and agonistic behaviors and the sex of the adult baboon performing the behavior will be statistically significant. Specifically that males will be observed performing agonistic behaviors more than female baboons but that affiliative behaviors will not be dependent of sex. My second hypothesis predicts that there will be a significant relationship between troop behavior or habitat and specific communicative behaviors. The purpose of this study is to further our current knowledge of Papio anubis intra-species communication and any effects of sex, habitat and majority troop behavior on communication. Sharing your land, especially farmland, with wild animals is no easy trial and Tanzanians face the struggle of their crops being raided by wild animals with a government that has not yet found successful ways to alleviate this tension. Utilizing the information gained from this study could allow for greater insight into the cognitive abilities of the species, our ability as humans to interact with the species, and the most effective ways to implement protective or conservation plans for Papio anubis.
Study Site
The site of this study is the village Mto Wa Mbu of Northern Tanzania, located west 120 kilometers from the city of Arusha. Home to Lake Manyara National Park, Mto Wa Mbu supports a growing population of humans along with troops of baboons up to 300 in number. Lake Manyara National Park, located just on the outskirts of the area of Mto Wa Mbu, also borders along 50 kilometers of the Tanzanian rift valley. The park spans the area of 648 square kilometers and supports not only large troops of Papio anubis but also Equus quagga (zebra), Hippopotamus amphibious, Bubalus bubalis (buffalo), Connochaetes (wildebeest), and Cercopithecus mitis (blue monkey) to name just a few species I encountered during my time inside the park. The distinct and numerous habitats in the area are supported by three rivers: Magadini, Kirurumu, and Mahamoud. The park serves as a common starting point for tourists traveling through the national parks, along with Tarangire, Ngorongoro Crater, and Serengeti. The park boundaries occur immediately west of the Makayuni-Karatu road bordering the most southeast region of the park. The lack of boundaries allows for species to freely migrate to and from the park. This also allows for humans to illegally enter the protected area in order to extract wood fuel or bush meat. Olive Baboons are one of the species that is a prominent member of the population outside of the park.
Exiting the park to forage, the baboons leave protected boundaries early in the morning once the sun has risen and return in the evening to find shelter in tall trees. Individuals of the same or differing clans interact daily in different habitats outside the park. Communication occurs within a clan, between clans, in different habitats, and during the performance of different troop behaviors. The habitats frequented are Riverine, Shrubland, Woodland, and Roadside. The majority troop behaviors observed are Grooming, Resting, Moving, and Foraging.
The Riverine habitat refers to the river that runs into the national park perpendicular to the Makayuni-Karatu Road in Mto Wa Mbu that provides vegetation in which baboons will move through, foraging for food as well as resting in its shade, and often grooming. In this habitat it is not uncommon for humans to pass by on bicycle, with cattle, in a car, or on foot and for multiple clans to gather.
The Shrubland habitats found outside of the park are dispersed between riverine and woodland habitats. The baboons were often found resting, foraging, and grooming in these locations or simply passing through. During the study it was observed that less human interaction with baboons occurred in these habitats as fewer roads and paths crossed entered these shrublands.
Figure 3: Shrubland habitat, Mto Wa Mbu, Tanzania. Picture by Francie Saunders 2016.
Woodland habitats are common throughout the study site and are found stretching up the escarpment of the Rift Valley and between other habitats. Baboons enjoy foraging for fruits and resting in the various species of trees.
Figure 4: Woodland habitat Mto Wa Mbu, Tanzania. Pictures by Francie Saunders 2016.
The Roadside habitat is categorized separately from other habitats but includes all habitats adjacent to the road. I found it significant to classify this habitat separately from simply shrubland, woodland, or riverine as the Makayuni-Karatu road habitat varies drastically from the others. This road has consistent traffic of all kinds including: safari cars, motorcycles, bicycles, foot traffic, cattle and herders, dogs, and delivery trucks. Troops are exposed to a vast amount of human activity and direct human interaction daily while also benefitting. Baboons are able to forage through the litter that accumulates on the side of the road or make quick excursions into bordering farms to forage on crops.
Figure 5: Makayuni-Karatu Roadside habitat in Mto Wa Mbu, Tanzania. Pictures taken by Francie Saunders 2016.
Methods
This study was conducted from April 6th to April 20th for a total of 15 days of data collection on the communicative behaviors of Papio anubis in Mto Wa Mbu, Tanzania. Three initial preparatory days were used as an investigative period to determine the usual locations of the troops during certain times in the day as well as observe for facial expressions and vocalizations of interest. These days were additionally used to determine appropriate time intervals for scan and focal sampling. The sample frame for this study was troops of Olive Baboons that reside in Mto Wa Mbu and the sample population were troops that exited Lake Manyara National Park during the day. This study was determined to be representative of the troops of baboons in Mto Wa Mbu. The troops and their habitat site at which I collected data were accessible by foot and allowed for exceptional navigation of the area by both investigators and subjects. Observation of the baboons took place for 4 hours a day in the morning for 15 days between the time slots of 7am-11am and 8am-12pm.
Observation occurred in the morning as the preparatory days found that the baboons performed various troop behaviors and visited multiple habitats in the morning compared to the afternoon where activity was found to be limited. Also, in the afternoon subjects were difficult to locate and follow, most often because troops had returned to the National Park and I was unable to follow and observe them as the park is out of the boundaries for this study.
Data was collected using focal sampling and scan sampling. Data was recorded in behavioral ethograms found in Appendix C and D. My partner, baboon expert Stanley Darabe of the Mto Wa Mbu Cultural Tourism Program, assisted me in locating the troops as he was familiar with their usual schedules and preferred locations outside of the park. Therefore a limited amount of time was spent searching for the subjects which allowed more time to be dedicated to observation. Once the troop was located I allowed for a five-minute habituation period to avoid a bias of baboon behavior caused by our presence. After a two days the baboons seemed comfortable and undisturbed by my presence. Metadata was collected for three minutes before sampling and recorded the correlates habitat and majority troop behavior. Habitats were categorized by Roadside, Riverine, Woodland, and Shrubland (Figures 2-5). Majority troop behaviors were recorded as Grooming, Moving, Foraging, or Resting. Grooming included auto- and social-grooming by the baboons. Moving was recorded when a majority of the group were in locomotive motion without foraging. The behavior of Foraging included stationary foraging as well as foraging while moving. Resting was recorded when the majority of the troop was stationary in their habitat, neither grooming nor foraging, and usually sleeping.
Focal samples occurred at least eight times during the four-hour observation intervals. Adult males and adult females were randomly selected, choosing every second individual as the subject. Focal scans allowed for an initial three minutes to record metadata, habitat, and majority troop behavior followed by five minutes dedicated to recording any facial expressions or vocalizations performed by the individual.
Scan samples also occurred at least eight times during the four-hour intervals. Again, three minutes were allowed for meta-data recording before the ten minute behavioral scan began. Starting from left to right the scans focused on all individuals of the group. For these scans all communicative behaviors were recorded regardless of the age class of the individual. I found the inclusion of the behaviors of juveniles and subadults to be relevant in these scans considering that communication and learning are essential components of primate development.
Behaviors were observed and recorded in behavioral ethograms (Appendix C & D). Metadata noted the time and date, habitat, majority troop behavior, weather, presence of humans or other species, and any other relevant information about the conditions of the surrounding environment. If the troop or the specific individual went out of sight this was recorded in the data as “out of sight” and the sampling would begin again once the individuals or individual reappeared. Seeing as the majority of the troop is an important focus of this study, if a small portion of the troop ventured out of sight or into new habitat their behaviors were not recorded but the behaviors of the majority of the troop remained under observation.
Modes of analysis utilized a descriptive look at trends, examining the relationship between the frequencies of behaviors, habitat, and majority troop behavior. Some specific behaviors have been classified as affiliative and agonistic. This intent, affection or aggression, and majority troop behavior or habitat were analyzed for significant correlation using chi-square analysis. A chi-squared test was also used to examine focal sampling data to reveal any correlations between sex, habitat, majority troop behaviors, and the performance of communicative behaviors with the confidence interval of 90% or a critical value of α=0.10.
Results
Over the 15-day duration of the study 137 13-minute-scan and 168 8-minute-focal samples were obtained. This sums to a total of 3,125 minutes, or 52.1 hours, of observation and a sample total of n=305. Focal sampling occurred a total of 168 times with an equivalent sampling of the communicative behaviors of 84 adult male and 84 adult female baboons. Figure 6 demonstrates the troop’s time budgets (Grooming, Resting, Moving, Foraging) in relation to each of the four habitats of Roadside, Riverine, Woodland, and Shrubland.
Figure 6: This figure represents the Majority Troop Behavior Time Budget of Papio anubis for each of the four habitats examined in Mto Wa Mbu, Tanzania. This graph portrays the distribution of troop behaviors using the total number of focal and scan samples (n=305) which had recorded one of the four troop behaviors as the majority’s in each habitat from April 6 to April 20, 2016.
As represented in Figure 6 and 8, sampling most often occurred in the Roadside habitats and least often in the Woodland habitats. A total of 101 samples, 56 focal and 45 scans, were taken in Roadside habitats while the Woodland habitats hosted 49 samples, 24 focal and 25 scans. The troop behavior of Resting occurred during 34.8% of observation time and Foraging in 33.8%, being the two most commonly performed troop behaviors observed in this study. Grooming and Moving were observed for 14.4% and 17.0% of all focal and scan samples, being the least common troop behaviors observed (Figure 7).
Figure 7: Majority Troop Behavior Activity Budget of Papio anubis in Roadside, Riverine, Woodland, and Shrubland habitats. Calculated from the total number of focal and scan samples (n=305) for each of the four behaviors that occurred during observation from April 6-20, 2016 in Mto Wa Mbu, Tanzania.
Figure 8: Percentage of observation time spent in each of the four habitats examined in Mto Wa Mbu, Tanzania. Percentages calculated from the total number of samples (n=305) and specific number of samples taken in each habitat from April 6-20, 2016.
In the Roadside and Shrubland habitats, in which over half of sampling occurred (197/305), Foraging is shared as the most common troop behavior observed during data collection. Figure 6 shows the distribution of troop behaviors in each of the four habitats. In Roadside habitats 101 troop behaviors were recorded with 38/101, or 37.6%, samples noting Foraging as the majority troop behavior. For Shrubland habitats, Foraging was recorded as the majority troop behavior in 49/96 samples, occurring 51% of observation time. Of the 59 Riverine habitats samples collected, 33 samples, or 56%, observed Resting as the majority troop behavior. Resting was also found to be the most common troop behavior in Woodland habitats, with this behavioral event occurring in 24/49 samples, or 49% of observation time. Riverine habitat samples observed Foraging as the least common troop behavior occurring in 6.7% (4/59) of samples. Moving was observed least often in Shrubland habitats with 12.5% of samples noting this behavior (12/96). Woodland and Roadside habitats recorded the majority troop behavior of Grooming least often with 8% and 11% of samples noting this behavior (4/49, 11/101).
In depth descriptive analysis of frequency of agonistic and affiliative behavior observed during scan sampling was also conducted to reveal any relations between majority troop behavior and habitat. Canine display, eyebrow raise, screeching, and staring were the agonistic behaviors analyzed. Frequency was determined by the number of instances when the behavior was recorded in relation to the total instances in which the behavior was observed. Screeching was observed most commonly in the Shrubland habitats (71/210) and when the majority of the troop was resting (91/210). Eyebrow raising was observed equally in Riverine and Roadside habitats (18/51) and observed most frequently when the majority of the troop was resting (30/51). Staring was observed most in Riverine habitats (23/57) and again when majority troop behavior was resting (38/57). And canine display occurred in Roadside and Woodland habitats equally (3/8) while most commonly observed when the troop was moving (4/8). The facial expression and vocalization examined for affiliative behaviors were: lip smacking and rhythmic grunting. The affiliative behavior of lip smacking was observed most frequently in Roadside habitats (8/16) and when the majority was foraging (7/16). The performance of rhythmic grunts was recorded in greatest frequency in Shrubland habitats (87/198) and again when the majority of the troop was foraging (81/198).
A chi-square analysis revealed that the majority troop behaviors of Grooming, Foraging, Moving, and Resting are not independent of the habitat (Riverine, Roadside, Woodland, or Shrubland) in which they were performed. Utilizing the null hypothesis that majority troop behavior is independent of habitat, the analysis found x2=54.3252 with p<0.00001. These results are significant and the null hypothesis rejected at p-value < 0.10 with a 90% confidence interval (α=0.10).
Agonistic behaviors performed by male and female adult baboons were analyzed with a contingency table to examine whether the performance of certain communicative behaviors are independent from the sex of the individual in the sample population. The critical value used was α=0.10 for a confidence interval of 90%. The chi-squared analysis examined all focal samples recorded despite variances in habitat or majority troop behavior (n=168, m=84, f=84). Figure 9 represents the observed frequencies of these agonistic behaviors in relation to sex. Although the behavior of Roaring is considered an agonistic behavior this was not included in analysis as it is classified as being exclusively performed by male baboons. The analysis revealed significant results that agonistic baboon behavior is not independent of sex in the population sampled (x2 = 9.109, p=0.02787, α=0.10).
Figure 9: Frequency of agonistic Behaviors performed by Male and Female adult baboons (m=84, f=84) that occurred during observation in all habitats and during all majority troop behaviors from April 6-20 2016 in Mto Wa Mbu, Tanzania.
Affiliative behaviors were also analyzed with a contingency table, utilizing the same parameters as above, examining whether the performance of affiliative communicative behaviors is independent from the sex of the individual in the sampled population. The analysis revealed the results x2 = 0.7618 and p=0.3828, finding that affiliative baboon behavior is independent of the sex of the individual in the sample population with a p-value > 0.10. Figure 10 visually represents the frequency of affiliative behaviors observed during focal sampling.
Figure 10: This figure represents the frequency of Affiliative behaviors performed by Male and Female adult Olive Baboons in all focal samples (n=168) observed from April 6-20, 2016. Mto Wa Mbu, Tanzania.
Scan samples that observed agonistic and affiliative communicative behaviors were also examined separately to reveal any relationships between these behaviors and habitat (n=137). The same agonistic and affiliative facial expressions and vocalizations were analyzed in contingency tables with a critical value of α=0.10. The analysis found that both agonistic (eyebrow raise, staring, canine display, screeching) and affiliative behaviors (lip smacking and rhythmic grunting) are not independent of habitat type. Analysis of agonistic behaviors and habitat found the values of x2=26.18 and p=0.0019. Analysis of affiliative behaviors in scan samples and habitats revealed the results of x2=16.43 and p=0.000926.
Observed affiliative and agonistic communicative behaviors were then analyzed in relation to the majority troop behavior (Grooming, Foraging, Moving, or Resting) during which they were performed in scan samples (n=137) with a critical value of α=0.10. Analysis revealed that agonistic behaviors were not independent of troop behavior of the sampled population with the results of x2=27.148 and p=0.001322. Affiliative behaviors examined with contingency tables revealed that these behaviors are independent of majority troop behaviors for the sampled population. Analysis of affiliative behaviors yielded the values x2=0.699 and p=0.8734
Discussion
For this study I hypothesized that performance of agonistic behaviors would be dependent of sex while affiliative behaviors would be independent of sex. My second hypothesis predicted a significant relationship to exist between troop behavior or habitat and specific communicative behaviors. Given the proportion of males to females, differences in body size, and the fact that females place in the social hierarchy is determined early on, I hypothesized males would perform agonistic behaviors more often than females as a means of establishing and maintaining social rank. I also expected that specific habitats would elicit certain majority troop behaviors, which would then influence the communicative behaviors performed by the baboons.
Overall use of four habitats
As seen in Figure 8, my results found the majority of observation time to have occurred in Roadside habitats with a total sample size being n=101 out of 305 total samples. This can most likely be attributed to the variety of troop behaviors that can be performed in this habitat. There was a relatively even distribution of troop behaviors in the Roadside habitats in comparison to the other habitats with time spent 37.6% foraging, 26.7% resting, 24.8% moving, and 10.9% grooming (Figure 5). Given that this environment is shared with humans, baboons can forage from food or trash that ends up on the sides of the roads. Individual baboons would often steal crops from farms bordering the road, search through the ditches on the road for forgotten food or trash, and dig in the dirt to find small morsels of food. Since one side of the road is within the National Park boundaries, baboons were also able to find some refuge from the human activity in order to groom and rest in this habitat’s shade and vegetation. Although I might have expected the baboons to avoid human interaction, it seems as though the troops have largely habituated to the presence of humans in their environment. The road also served as a helpful route for baboon travel as groups were often found moving west to east along the road, using the area to travel to and from different habitats while utilizing the relatively protected, National Park side of the road. Because of its resources, this habitat provided the opportunity for troops to perform more behaviors (grooming, foraging, moving, and resting) and consequently spend more time there.
The least amount of scans occurred in the Woodland habitats. I would attribute this to the normally observed behaviors of baboon troops including frequent foraging. This could also be a result of my inability to access all forms of Woodland habitat and limitations of my methods. Troops spend most of their time foraging throughout the day without breaks of inactivity (Estes 1991). This differs from other primate species that tend to forage in the morning and afternoon, avoiding the hot temperatures in the middle of the day. Although I would observe the baboons foraging in Fig Trees in the Woodland habitats, I recorded that a majority of the time this habitat (n=24/49) was utilized for Resting by the majority of the troop. Therefore I would attribute this result to the natural behaviors of Olive Baboons that prefer to regularly forage on grasses.
Majority troop behavior and habitat
This study found majority troop behavior to be dependent of habitat. Roadside habitats noted Foraging as the most common troop behavior observed for reasons stated above. Shrubland habitats also were recorded having the majority of troops Foraging for 51% of all samples in this habitat category. As Papio anubis spend most of their foraging time feeding on grasses , this behavior is not surprising. The Shrublands in this study site had plentiful grasses from which to forage, possibly attributed to it being the wet season in Tanzania.
Riverine habitats were recorded as having Resting as the majority troop behavior for 56% of samples. The large, dark colored rocks that line the shore of the river serve as preferred resting spots for the baboons, especially on cloudy and rainy days when troops wait for the sun to emerge before moving through the dewy vegetation. This habitat also allows for a relatively wide lensed view of the surrounding areas, perhaps making it easier for troop cooperation or to detect oncoming threats, such as the humans of Mto Wa Mbu and occasionally their dogs. Woodland habitats also shared Resting as the most frequently recorded troop behavior with 49% of samples noting this activity. Although Resting was the most frequent I find it important to note that 24.5% of samples in this habitat noted Foraging as the majority troop behavior. Baboons were often transferring from tree to tree, foraging in Fig Trees where they feed on the wasp larvae within the fruits. The trees also served as safe and vigilant resting spots approaching the time when the sun was overhead and the temperature at its hottest.
Agonistic and Affiliative behaviors in relation to sex
Agonistic and affiliative communicative behaviors were examined, looking at focal and scan samples, in order to reveal any variations or trends in the data concerning habitat, sex, or troop behavior. I hypothesized that agonistic behaviors would be dependent of the sex of the individual while affiliative behaviors would not. A chi-square analysis found that the sex of an adult baboon and the performance of agonistic behaviors were dependent of each other. These results support my hypothesis that sex of adult baboons and the performance of agonistic behaviors are correlated. Males were observed performing agonistic behaviors significantly more than the females of the sampled population in all habitats and during the performance of any of the troop behaviors (Figure 9). From my observations, I often found males to be the individuals to settle an aggressive interaction between other baboons or to behave in a manner of overt dominance more often than I observed females doing so.
Perhaps this can be attributed to the dramatic sexual dimorphism that exists in this species, as males with a larger body size can more easily threaten individuals and use their own strength if needed compared to the smaller bodied female adults. I also attribute this result to the strict hierarchy of females. Rank is determined very early on in life for female baboons contrary to male baboons who emigrate and must acquire and maintain a dominant rank within a troop or clan.
I also hypothesized that affiliative behaviors would not be significantly correlated with the sex of the individual baboon. Analyzation of focal samples of males and females revealed that the affiliative behaviors examined in this study were independent of sex in the sample population, supporting my hypothesis. I would suspect it to be in the interests of most all adult baboons, despite difference in sex, to maintain group cooperation. Amicable intentions and actions avoid aggressive encounters and strengthen bonds between individuals. This cooperation would benefit both male and female baboons through the avoidance of the potentially, very harmful consequences of an aggressive encounter as well as the reception of benefits like grooming and food sharing that result from friendly relationships.
There was a specific clan of baboons that I observed every day that hosted two distinct, large males. One male was most obviously the alpha male, with a strong and large body, and the other male was estimated to be older and was wounded on his upper shoulder and the side of his snout. Whenever the strong male would come near the other, the injured male would perform the behavior of lip smacking and would be eager to move out of the way of the other male if need be. The strong alpha male almost always returned the lip smacking behavior and did not engage in any agonistic behaviors towards the injured male, despite the fact that this was another mature adult male who could threaten his dominance. This relationship was not observed between any other adult males during my time of data collection. It seems that the strong male allowed the injured male to remain in his clan as a submissive and lower-ranking member. This amicable relationship seemed to be supported and maintained by the use of affiliative communicative behaviors.
In relation to habitat
I hypothesized that certain communicative behaviors and habitat would have a significant relationship. The basis of my hypothesis considered that given varying conditions in different habitats, certain troop behaviors would be performed more than others and therefore result in specific and corresponding communicative behaviors. Analysis found that agonistic and affiliative behaviors recorded during scan samples were not independent of habitat. Depending on habitat, individuals were observed performing either a higher frequency of agonistic or affiliative behaviors. For instance, when in the Roadside habitats I recorded that screeching was 65% of the agonistic behaviors performed. Screeching serves as a way to inhibit aggressive encounters and express fear. The conditions of the roadside provided competition for food and also required the avoidance of human activity which may increase stress levels in the baboons. These conditions may have resulted in a high frequency of aggressive encounters that caused an individual to perform the screeching vocalization. This high percentage could also be attributed to the fact that I included the behaviors of subadults in my scans, who may be more likely to vocalize a screech than adult baboons.
The threatening facial expression of staring was recorded most frequently in the Riverine habitats. Eyebrow raising was observed most frequently in both Riverine and Roadside habitats. I found that when the majority of the troop was resting, which was not uncommon in Riverine and Roadside habitats (33/59, 27/101), adult baboons would often scold younger baboons for play fighting or screeching if the locomotion or vocalizations became a disturbance to others. I observed many adults perform staring and eyebrow raise to both subadult and other adult baboons. These facial expressions can serve as tactics in avoiding aggressive encounters or threatening another individual into submission or cooperation.
The affiliative behavior of rhythmic grunting was more frequently performed than that of lip smacking in all four habitats. Rhythmic grunting was performed by male and female adult baboons alike (Figure 10). My observations found that it was often performed before or after lip smacking and that it expressed friendly intent as it was commonly followed by grooming or amicable, close proximity.
In relation to majority troop behavior
From chi-square analyses I found that although agonistic behavior is not independent of majority troop behavior, affiliative behaviors were independent of majority troop behavior. This being that despite grooming, foraging, resting, or moving by the majority of the troop the frequency of affiliative behaviors during each did not vary significantly. I would attribute this to the importance of maintaining social relationships and group cooperation despite the behavior of the majority of troop members. I suspect that given the conditions during the four different troop behaviors, certain activities coincide with agonistic behaviors compared to others. For instance, during foraging there is competition for resources. On the other hand, when the majority was grooming many troop members were dozing off or focused on grooming themselves or another baboon. Resting can draw back to the example for the Riverine habitat. When most of the troop was resting, subadults were often playing and possibly disturbing other baboons resulting in a threatening or scolding behavior. And when moving, I expect the troop would be most occupied with reaching their destination than maintaining social structure.
Limitations and Biases
Given the nature of this study there were observational and methodological biases and limitations that could affect its results.
Methodological
My inability to physically, legally enter the national park was a methodological limitation. If the troop as a whole or members of the troop entered the park I was unable to follow and observe any behaviors performed during that time.
This study would have been more effective with the use of multiple observers. Having only one observer, myself, may have inhibited my ability to see all members of the troop at one time and properly record behaviors.
Specific classification of communicative behaviors and their hypothesized “meanings.” I was unable to locate an in depth list of facial expression and vocalization of Papio Anubis and therefore my classifications in my ethograms may not be accurate to past or future published work pertaining to their communicative behaviors.
Observational
Depending on habitat, baboons were occasionally difficult to observe. For instance in shrubland baboons were not uncommonly passing through or resting in a bush, therefore creating a visual obstruction for my observation. Troops enjoyed foraging in tall trees, such as the Fig Trees, and therefore provided another visual limitation for my observations.
Observation of facial expressions proved difficult when subjects faced away from me. Also some vocalizations are quieter than others and if I was too far away to hear I could have missed the performance of such a behavior. This could allow for unobservable and unrecorded facial expressions and vocalizations that were performed during sampling.
Human-wildlife interactions. The conflict between baboons and humans in Mto Wa Mbu is easily identifiable. Often children and adults would pass troops of baboons and throw rocks or sticks or yell at the animals, altering their behavior and often scaring them out of view. I observed many instances where young boys herding goats sent their dogs to chase and frighten the baboons I was observing.
The species is mobile. Although most habitats were easily accessible, if a whole troop was moving it often made scanning more difficult and could have allowed for the missed recording of a communicative behavior. Again, multiple observers would prove quite helpful for this study.
Recommendations
If another study was to be done focusing on Papio anubis communication I would recommend further exploration of the classified communicative behaviors of the species or species similar to it. Also the study could incorporate the use of body language by individuals as means of communication. Becoming familiar with these behaviors beforehand, along with possible intent or meaning of the behavior, and being able to differentiate clearly would greatly benefit this study. In technical terms, it may be quite useful to utilize multiple observers given the often, large number of individuals under observation. This may provide for a greater understanding of the interactions between baboons. Interviews could be conducted with local villagers examining the issues that exist between the Olive Baboons and the people of Mto Wa Mbu.
For future studies I would recommend the incorporation of other correlates such as who the specific interaction occurs between. This would be very interesting and possibly provide further knowledge about the social structure within clans and troops. While focusing on one individual and its behaviors towards another the age class and sex of both could be recorded and later examined. I often observed the black-phase infants and their mothers being treated by other baboons quite differently than the interactions I saw between most baboons. Rhythmic grunting and lip smacking were performed while an individual lowered itself to the ground and put its face close to the infant. I also witnessed aggressive action taken towards a mother and her black-phase baby by other adult males and females. Another interesting observation occurred between males and social mounting of one another. In one clan a certain large alpha male would often nuzzle other members of the clan and I did not observe any other baboons perform this action during my time of observation. A study that focuses on interactions between baboons could reveal significant relationships that exist within the complex social structure.
Conclusion
The Olive Baboons of Mto Wa Mbu have demonstrated that specific communicative behaviors are performed depending on sex, habitat, and majority troop behavior. Depending on habitat, troops alternated their behavior between foraging, grooming, resting, or moving. The conditions of different habitats resulted in the likelihood of specific behaviors being performed by the troop. For instance the Shrubland habitats observed Foraging most often. Agonistic and affiliative behaviors were dependent of habitat while only agonistic behaviors were dependent on majority troop behavior. The performance of agonistic behaviors was found to be dependent of sex of the individual baboon while the opposite was found concerning affiliative behaviors. While males were observed to perform agonistic behaviors more frequently than females, it is in the interest of both sexes to maintain amicable relationships within the troop.
My study revealed that there are complex and not completely understood communication mechanisms utilized by this species. Even further than vocalizations and facial expressions, this species relies on body language to interact with other individuals. Any direct involvement that could affect the wellbeing of species’ members must be prefaced with a deep understanding not only of the ecology of the species but also intricate systems functioning within, such as that of communication. Most importantly the relationship between individuals and the various types of interactions that can occur depending on sex, habitat, or majority troop behavior can give great insight into what would be the most effective means of working with the species if protection or conservation becomes necessary.
While habitat loss, pollution, and the human-wildlife conflict grow rapidly worldwide, species become vulnerable to the drastic changes in their environments and require proactive efforts by the same human population threatening its very existence on this planet. Conflict between humans and wildlife has existed long before today and will exist long after. While these issues grow larger and the need to assist certain species becomes apparent, we must know as much as possible about the natural life of a species before taking any action in order to ensure success. Extensive understanding of the conflict between the humans and wildlife is equally significant to having an comprehensive understanding of the species itself. Learning the intricate details of species’ behaviors will greatly assist the creation of a profound connection with the world around us that can only serve to benefit the lives of all.
Works Cited
Britt, A., Welch C., & Katz A. (2003). Can small, isolated primate populations be effectively reinforced through the release of individuals from a captive population?. Biological Conservation, 115, 319-327.
Cunningham, E. & Janson, C. (2007). A socioecological perspective on primate cognition, past and present. Animal Cognition, 10, 273-281.
Estes, Richard. 1991. The Behavior Guide to African Mammals. University of California Press. California.
McGrew, W.C. (1981) Social and cognitive capabilities of nonhuman primates: Lessons from the wild to captivity. International Journal for the Study of Animal Problems, 2, 138-149.
McDougall, P.T., Réale, D., Sol, D., & Reader, S.M. (2006). Wildlife conservation and animals temperament: causes and consequences of evolutionary change for captive, reintroduced, and wild populations. Animal Conservation, 9, 39-48.
Strum, S. C. (2012), Darwin's monkey: Why baboons can't become human. American Journal of Physical Anthropology, 149, 3–23. doi: 10.1002/ajpa.22158
Appendix
Appendix A
Ethogram of Facial Expressions _
Behavior: Definition
Staring: Threat display by all baboons, Eyebrows raised, scalp retracted, white eyelids displayed, eyes fixed on stimulus
Canine Display: Threat display by adult baboons, Often performed with eyebrow raising
Eyebrow Raising: Aggressive gesture, Baboon raises eyebrows
Fear Grimace: Appeasement signal to reduce aggression, Lips retracted to show teeth clenched together, Used as a sign of submission in aggressive encounters
Rapid Glancing: Turn head away and look elsewhere, Performed by threatened baboon to decrease tension
Lip Smacking: Reassuring display by adult baboons, Lips protruded and smacked together repeatedly
Appendix B
Ethogram of Vocalizations _
Two Phase Bark “wahoo” deep, loud call
2-5 second intervals
Inter- or intra- group aggression between males
Grunting “uh-huh” soft, two phase call
Adult male threat call
Roaring “wahoo” crescendo
Adult male during fights
Screeching Repeated, high pitched screams
All age classes and sexes
Respond to dominant aggression to inhibit aggression
Yakking “yak” short and sharp
subadult, adult male, adult female
Given by individual withdrawing from threatening animal
Often accompanied by fear grimace
Rhythmic Grunts Low, soft call
Adult male, adult females, subadults but not infants
Signals friendly intentions
Doglike Bark High pitch, more quaver “woah” “uff”
Adult male, adult female, subadult, often given when separated from the group
Appendix C: Ethogram of Facial Expressions and Vocalizations for Scan Sampling
Appendix D: Ethogram of Facial Expression and Vocalizations for Focal Sampling
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