Aggression in Anubis Baboons (Papio anubis): Initiation and Duration of Social Grooming in Lactating and Non-lactating Females and the

Establishment of Male Friendships Rachel M. Orobono, Dept. of Biological Sciences

Project Summary Lactating female baboons maintain close associations with particular males that may protect her infant from infanticide by a newly immigrated alpha male (Palombit et al. 2001). Although social grooming is regularly used by females, the extent to which grooming plays a role in the formation and maintenance of social relationships is not well characterized. This study may provide a better understanding of the formation and maintenance of social bonds in anubis baboons.

Introduction Social grooming among primates is a process by which strong social relationshipscan be formed; a large portion of social interaction is invested in this behavior. It is known that primates use social behavior to sustain relationships with one another (Palombit et al. 2000). It has been suggested that in order to decrease infanticidal behavior from dominant males, females may increase their social behavior with selected males (Harcourt and Greenberg 2001). Although this shows that grooming may be used as a strategy by females, the extent to which grooming plays a role in the formation and maintenance of social relationships is not well characterized. The objective of this study is to find a relationship between the degree of female-male social grooming and the degree of male-infant aggressive behaviors in anubis baboons (Papio anubis). I propose that a female who is lactating will (1) initiate grooming with a male more often, and will (2) take part in a longer grooming period than if she were not lactating. This study will provide us with information crucial to the understanding of primate social behavior. It is beneficial to gain such knowledge because the mechanism(s) of the formation and maintenance of primate social bonds remains unknown.

Review of Literature•Associations with male friends are negatively correlated with the probability of infanticide in Gorilla gorilla (Harcourt and Greenberg 2001).•Female mountain baboons reserve grooming time for specific males (Henzi et al. 2000). •Female Japanese macaques (Macaca fuscata) may prevent certain males from joining their troops (Packer and Pusey 1979). •Female behavior towards males has an effect on male associations with females in Papio anubis (Packer and Pusey 1979). •Lactating female chacma baboons maintain friendships with selected males that may potentially protect their infants from dominant males (Palombit et al. 2000). •Baboons use social behavior to maintain male-female relationships (Palombit et al. 2000)

Objectives•To compare the number of aggressive behaviors toward infants to the number of times grooming was initiated by mother•To compare the number of aggressivebehaviors toward infants to length ofgrooming periods by mother•To compare the degree of establishedfemale-male relationship to the number ofaggressive behaviors towards infants (according to categories of friendship)•To compare male-infant relationship to thenumber of aggressive behaviors by male (according to categories of friendship)

Overall H°•There is a negative relationship between the degree of female-male social grooming and the number of aggressive behaviors that take place towards the infant

•Harcourt, A. H., and Greenberg, J. 2001. Do gorilla females join males to avoid infanticide? A quantitative model. Animal Behaviour 62: 905-915.•Henzi, S. P., et al. 2000. Social Bonds and the Coherence of Mountain Baboon Troops. Behaviour 137: 663-679.•Packer, C. and Pusey, A. E. 1979. Female Aggression and Male Membership in Troops of Japanese Macaques and Olive Baboons. Folia primatol 31: 212-217•Palombit, R. A., Cheney, D. L., and Seyfarth, R.M. 2000. Female-female competition for male “friends” in wild chacma baboons, Papio cynocephalus ursinus. Animal Behaviour 61: 1159-1169.

Literature Cited

Acknowledgments

Dr. Bradley Rehnberg

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Figure 2. Number of initiations by female vs. number of aggressivebehaviors by female

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Figure 3. Number of aggressive behaviors by male vs. length ofgrooming period (female-male)

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Establish friendship categoriesGood friendFriendAcquaintance Stranger

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Research DesignObservation of free-ranging anubis baboons in Gombe National Park,

Tanzania, African=60-80

2 year studyPilot Study Determine

Dominance ranks

Determinematernalrelations

Main Study

Behavioral

Observations

Recordbirths

Establish initiation categoriesHighest %Average %Lowest %

Establish aggression categories

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Figure 4. Hinde's Index: Lactating vs. Control

State of female

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Figure 1. Aggressive behaviors vs. male-female friendship staus

Male-female friendship status

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