Intergroup relations

Baboons and Mangabeys

DEFINITION Home range: Area exploited by a group of primates (defended but not exclusively)

Overlap between home ranges

Territory: Area exploited and EXCLUSIVELY defended by primates

No overlap betweenterritories

Home range / TerritoryNon-territorial primates defend a clumped, desirable food source, such as large fruiting trees.

Ex: capuchins, red howlers, baboons, mangabeys, great apes

These species require large home ranges, relative to their day ranges (distance travelled in one day). They cannot keep intruders out of their home range at all times.

No overlap in territories. Possible to defend EXCLUSIVELY a territory if the day range is roughly the equivalent of the radius of their home range.

Ex: gibbons, ring-tailed lemurs, tamarins, dusky titis, red-tailed monkeys (?), blue monkeys (?).

Strier 2003; Cheney 1987, In Primate Societies

Home range / Territory

Relationships between home range and other factors:

• The home range increases with species body weight

• Range increases with group size, both within and among species.

• Terrestrial primates have larger home ranges than arboreal primates

• Frugivores have larger home ranges than folivores

Rodman 1999, Ann. R. Anthropol.

Intergroup relations are clearly aggressiveaggressive,

although sometimes they are not.

For instance: red-tailed monkeys in Kibale NP

(Uganda). Sometimes they are, sometimes they

are not (pers. obs.).

Intergroup relations

Intergroup relations

Problem of definition: Cheney and Seyfarth (1977)

defined it for baboons as any approach of one

group within 500 m of another. Inappropriate for

primates with small home range / territory.

Cheney 1987, In: Primate Societies, 267-281. Chicago

UP.

This raises the problem of estimating encounter

rates.

Intergroup dominanceWhen home ranges overlap extensively, and are

not defended, the aggressive defence of a

resource (like a fruiting tree) may be costly.

-> Avoidance of other groups (Intergroup

Dominance).

Cheney 1987, In Primate

Societies

Intergroup dominance often determined by group

size, and the number of adult males in that group

(e.g. baboons, macaques). Not common when

territorial.

Sex differences ?Since femalefemale reproductive success appears

limited primarily by energetic and nutritional energetic and nutritional

constraintsconstraints, female grouping patterns are

influenced by food distributionfood distribution.

Cheney 1987, In Primate

Societies

Thus females are predicted to be more aggressive females are predicted to be more aggressive

toward femalestoward females of other groups than toward males,

or males toward males of other groups.

Sex differences ?

• In those primate species characterized by female female

dispersaldispersal, females tend NOTNOT to participate in intergroup encounters.

Cheney 1987, In Primate

Societies

• In contrast, males are hostile toward males are hostile toward

members of other groups, especially other members of other groups, especially other

malesmales. Such hostility seems to be related to the defence of females.

• Ex: chimpanzee, gorilla, red colobus.

Sex differences ?• In those primate species characterized by male male dispersaldispersal, females participate aggressivelyaggressively in intergroup encounters (almost all Old World monkey species).

• Female antagonism mostly against other females, sometimes against males. Related to the defence of food !

Cheney 1987, In Primate

Societies

• Males antagonism mostly against other males. Related to the defence of females !

• Ex: langurs, macaques, baboons, geladas.

Q. 4: WHY DEFEND A TERRITORY?

Strier 2007

Hypothesis:

Territorial behavior (defense of an area) depends on “economic defendability”.

“Economic defendability” depends on a low cost of defense (long day-range: small home-range)

Gorillas: NO

Vervets: YES

Siamang Chimpanzee Orangutan Gorilla

Relative size of core area

Distance traveled per day in relation to size of core area

Yes No No NoCore areas defended?

Wrangham (1979) Soc Sci Info

Diameter = d

Average day-range (path-length) = r

ID = Index of Defendability

= r/d

Core areaor

Home range

ID < 1 ID > 1

Cercopithecus (aethiops, mitis, ascanius)Callicebus (moloch, torquatus)

Colobus guereza (Dunbar)

Hylobates larSymphalangus syndactylus

Presbytis entellus (Yoshiba)

Lemur catta

Propithecus verreauxiIndri indri

Lepilemur mustelinus

Pongo pygmaeus

MiopithecusPapio ursinus

Lemur fulvus, mongoz

Saimiri oerstediAlouatta seniculus

0Territorial

NON-territorial

Presbytis entellus (Jay)

Macaca mulatta, radiata

Cercocebus albigenaTheropithecus gelada

Alouatta palliata

Colobus guereza (Oates), badius

Pan troglodytesGorilla gorilla

Papio anubis, cynocephalus

E. patas

Baboons and MangabeysBaboons and Mangabeys Share a recent common ancestor Part of the Afro-papionins :

savannah baboon, drill and mandrill, gelada, and hamadryas, mangabeys

Confusion between two groups of mangabeys : Cercocebus and Lophocebus are paraphyletic Now Cercocebus Mandrillus Theropithecus Lophocebus

Papio

Another confusion = taxonomy of savannah baboons From the same genus or not? Yes (Groves 2001). No (Jolly 1993)

Overall approx. 12 species of Afro-papionins

Mangabeys - LophocebusMangabeys - Lophocebus

L. aterrimus

L. albigena(feeding on figs (F. sansibarica)

Mangabeys - CercocebusMangabeys - Cercocebus

C. torquatus(self-grooming)

C. galeritus(feeding on yellow palm fruits)

GeladasGeladas

T. gelada(xeric habitat)

Hamadryas Hamadryas baboonsbaboons

P. hamadryas(hybrid zone with P. anubis)

Savannah Savannah baboonsbaboons

P. anubis(eating meat: gazelle)

Savannah Savannah baboonsbaboons

P. ursinus P. papio (AM following AF-oestrus)

P. cynocephalus (AM protecting infant)

Baboon social organizationBaboon social organization

Stable troopsStable troops >10 females>10 females > 5 males> 5 males

Henzi & Barrett (2003) Evol Anthropol

Anubis, olive

Yellow

“Savanna” baboons Hamadryas baboons (one-male units)

Savanna baboon social Savanna baboon social structurestructure

F-F: Strong alliances, dominanceF-F: Strong alliances, dominance F-M: Friendships (increases F F-M: Friendships (increases F

reproductive rate)reproductive rate) M-M: Dominance, some coalitionsM-M: Dominance, some coalitions Intergroup: Xenophobia +/- Intergroup: Xenophobia +/-

territorialityterritoriality

Female-female dominanceFemale-female dominance= stable, based on mother’s birth = stable, based on mother’s birth

rankrank

Laikipia anubis. Barton and Whiten (1993)

Agonistic relationships among females have few reversals.

Laikipia anubis. Barton and Whiten (1993)

High-ranking (female) baboons eat more

Females care about rank reversals between more than within families

Okavango (Bergman et al. 2003)

Female dominance hierarchies don’t always predict success

Cercopithecus mitis Blue monkeys, Kakamega (Cords 2002 Behaviour)

Cercopithecus mitis

Blue monkeys, Kakamega (Cords 2002 Behaviour)

Amboseli

Silk et al. 2003

But: sociality can be more important than rank (in promoting RS)

Chacma baboons, South Africa, Barrett & Henzi 2002, Behaviour

Grooming time is a measure of friendship.

But, it also responds to interest of infants.

Female-male friendshipsFemale-male friendships

Defining ‘Friendship’ between Female and Male.

(1) Spatial proximity.

Use ethograms to score dyads (range 0-20).

For most FF, top M scores ‘10’For most FF, top M scores ‘10’; the rest scores <3.

(2) Grooming.

Record all grooming bouts.

For average F, top M = 65% of her grooming65% of her grooming.

(3) Defining a ‘Friend’.

‘Friend’ = high score on BOTH proximity & grooming.

Characteristics of F-M ‘Friendships’Characteristics of F-M ‘Friendships’

(1) Approaches by Female.

To Friends: routine (feed, groom, travel)

To non-Friends: submissive, present, appease.

(2) Duration.

Similar age (often start as adolescence)

Could be lifelong.

(3) Distribution.

FF: 1-2 M Friends (FF sharing a M were also friends).

MM: 0-8 F Friends (high-rank MM had more F friends).

Benefits of F-M ‘Friendships’

(F1) Protection.

>90% of MM protecting a F were Friends.

(F2) Baby-sitting.

Intolerant of infants except Friends’.

(M1) Paternity.

Increased present and future probability of paternity.

(M2) Agonistic buffers.

Friends, especially infants, can be used as social buffers.

Male-male relations:Male-male relations:Dominance !Dominance !

Old “friends”

Agonistic buffering

Intergroup relationshipsIntergroup relationships

Xenophobia +/- territoriality

Chimpanzee Baboon

Philopatry Male Female

FM bonds None Strong

FF bonds Weak Strong

MM bonds Strong Few

Chimpanzee / Savanna baboon social structure compared

“The study of social behavior is no substitute for the study of social relationships.”

Robert Hinde (1981)