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Avoiding predation Hunting and sex
PredationRed
colobusStanford (2002)
Procolobus badius
Red colobus
Zanzibari red backed colobus monkey
Gambia red colobus monkey
Shoot-specialist
Large groups
High WSC (Snaith and Chapman 2005)
Multi-male (except Tana River)
Female emigration
Males jointly defend group
F-F alliances in W AfricaMale sexual ‘swellings’Key prey of humans/chimps
Predation rates on primates
Expect:Low rates (long life-span)
Explain by:
Arboreality
Few predators
Quick escape
GroupingLarge groupsMany males
Palatability?
LESS predation in:
Larger groups (r = -.49, P < .01)
Bigger species (r = -.40, P < .02)
Human-contact groups (r = -.95, P < .05)
% killed / yr
Ln (Group size)
15
0
% killed / yr
15
0
Body weight (kg)150
% killed / yr
100
0
Distance to human settlement (km)
20 1
Isbell (1994) Evol Anthropol
INFLUENCES ON PREDATION
ECOLOGICAL
EAGLE PREDATION AND
POLYSPECIFIC ASSOCIATION
EAGLES <-> SAME (monospecific) group size; POLYSPECIFICS
AMERICA AFRICA ASIA
Folivore Alouatta Colobus Presbytis
Predators
Eagle Harpy Crowned -
Mammal - Chimpanzee -
Group size 1-10 1-13 (+26) 1-8 (+14)
MM/F High High Low
PSAs Common Common Absent
# ADULT MALES
# ADULT FEMALES
4
1
1 10
COLOBUS
ALOUATTA
PRESBYTIS (arboreal)
Van Schaik & Horstermann (1994) BES
(1) MORE MALES IN SPECIES PREYED ON BY EAGLES
INFLUENCES ON PREDATION
SOCIAL
(2) LESS predation if More Male Defenders
(against chimpanzees)
Isbell et al 1993
Anim Behav
(3) LESS predation when settled in group
Cost of dispersal:
recent immigrants suffer higher mortality
Maybe because new
immigrants tend to live at the
edge of the group
(like subordinates often do)
VIGILANCE: TWO benefits?
1. Do larger groups detect predators better than smaller groups?
Prediction: Larger groups detect predators better
Detection
Group size
Vigilance rate
Blue monkey. Photo by A. Houle
VIGILANCE: 2 benefits?
Prediction: Larger groups reduce predator’s success
Survival
Group size
% successful kills
1. Do larger groups detect predators better than smaller groups?
RESULTS:
Group size can affect the detection distance
(distance at which monkeys saw or heard humans)
van Schaik et al 1983
Macaca fascicularis
Presbytis thomasi
P< 0.001
P< 0.05
P ns
P ns
M. nemestrina
Hylobates
VIGILANCE
2. Do large groups reduce the cost of vigilance?
Larger group -> less scanning (4 groups C. capucinus)
VIGILANCE: larger groups beneficialRose and Fedigan 1995 (Anim Behav)
% time spentVigilant
Time Alone
MM > FF
Who is most vigilant? (C. capucinus)
Rose and Fedigan 1995 (Anim Behav)
VIGILANCE (vervet monkeys)
Is male vigilance anti-predator?
Males spent a lot of time vigilant…
Males
October June ......... Mating season
Females
% time spentVigilant
Males are MORE vigilant
… but don’t alarm-call much!
Male vigilance directed at other males ?
“Vigilance” increases during mating season
Alpha male seen from top of canopy
Male vigilance may be selfish.
Males
% time Vigilant
Females
#Alarm Calls
Males are LESS efficient
Predation rates on red colobusGombe Kanyawara Ngogo Mahale Tai
% killed per year 5-15 < 1? > 10? 5? 10?
% adults 20-25 30 45
Big Brown (Nov 2004). Photo by A. Houle
LARGE GROUPS can ATTRACT PREDATORS (Gombe)
Population density (per sq km)
Group size
0 100 200 300
50
40
30
20
10
0
J
T
AM
TK
G+ CHIMPSGombeTaiMahaleKanyawara
- CHIMPS Jozani Abuko Tana
NO EVIDENCE THAT CHIMP-HUNTING BIG COLOBUS GROUPS
Budongo: no red colobus, and chimps do not hunt that much on other species
Effects of CHIMPANZEE HUNTING INTENSITY on Colobus demographyGombe (Stanford 1999)
50
40
30
20
10
0
G
G
G
G
G
Center S edgeSNN edge
Group sizeG
Chimpanzee community territory
J
J
J
J
J
% immatures
J
HUNTING and SEXMORE HUNTING PER ENCOUNTER with increasing n males
Chimpanzees
HUNTING and SEXMore success per hunt with increasing number of males (Gombe data)
Chimpanzees
% NFF [ = % feeding time on Non-Fig Fruits]
Kanyawara 1990-2000. Food seasons > 150 obsvn hrs.
r2 = 0.28n = 34
P < 0.005
Nu
mb
er
of
Ad
ult
+ A
do
les
cen
t M
ale
s What effect on hunting rate and success?
Kanyawara 1996-2000.
61 hunts, 9278 hours
r2 = 0.90n = 11
P < 0.0001
NUMBER OF HUNTS
PER 1000 HOURS
Number of Adult + Adolescent Males
‘## of Males’ > 150 obsvn hrs.
Gombe
Kanyawara
Number of males in party (adult + adolescent)0 2 4 6 8 10 12
80
60
40
20
0
100
% of hunts with at least one kill
For each site:r2 = 0.70, n = 13, p < 0.001
Number of Adult + Adolescent Males
> 40% NFF (non fig fruit)
< 40% NFF
Effect of fruit availabilityon hunting rates
NUMBER OF HUNTS
PER 1000 HOURS
r2 = .80, P < .001
r2 = .70, P < .01
WilcoxonP < 0.05
HUNTS
/ 1000 h
Number of Adult + Adolescent Males
Kanyawara 1996-2000. ‘## of Males’ > 150 obsvn hrs.
No swollen female
≥ 1 swollen female
WilcoxonP n.s.
Luxuryactivities
Swollen females
High-quality plant diet
More hunting
Largeparties
Nu
mb
er
of
Ad
ult
+ A
do
les
cen
t M
ale
s
% NFF [ = % feeding time on Non-Fig Fruits]
Kanyawara 1990-2000.
Increasing # males with NFF
r2 = 0.28n = 34
P < 0.005
Uvariopsis
Pseudospondias
Mimusops
Non-Fruit (THV)
Other Fruits
% NFF [ = % feeding time on Non-Fig Fruits]
Kanyawara 1990-2000.
Uvariopsis
Pseudospondias
Mimusops
Non-Fruit (THV)
Other Fruits
High residual
ANOVA (Bonferroni)
P < 0.005
Nu
mb
er
of
Ad
ult
+ A
do
les
cen
t M
ale
s
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Swollen females
Largeparties
High-quality plant diet
More hunting
Food type
Largeparties
High-quality plant diet
More hunting
SUMMARYFood type
Largeparties
High-quality plant diet
More hunting
WHY?
More hunting
Assesshunting success
Show-off to males
More Friends present
Large parties
HYPOTHESES TO BE TESTED
More hunting
High daily travel
Risk- prone
strategy
Low- protein
fruit
High-quality plant diet
HYPOTHESES TO BE TESTED
Kanyawara 1989-2001, n = 122 months, 110 kills
Ngogo 1995-2000, n = 37 months, 361 kills (Watts & Mitani 2002)
8
10
12
14
0 4 8 12 16 20 24
6
4
2
0
Number of males in party
# prey / hunt
NO INTER-SITE DIFFERENCE IN KILLS / HUNT (controlling for number of males)
0 4 8 12 16 >20
80
60
40
20
0
100
Number of males in party
% hunts successful
Gombe, Kanyawarar2 = 0.70, n = 13, p < 0.001
Gombe Kanyawara Ngogo
NO INTER-SITE DIFFERENCE IN % HUNT SUCCESS (controlling for number of males)
Gombe: Stanford 1998. Ngogo: Watts & Mitani 2002
Gombe: Stanford 1998:198
INTER-SITE DIFFERENCE IN HUNTING RATE?controlling for number of males
Gombe, n =
Kanyawara, n = 178% Red Colobus encounters Hunt
NGOGO 37%
Number of males in party
n = 92 encounters 178 12-h days,
1999-2001
Chimps hunt colobus r2 = .65, P < .01
Colobus supplant chimps r2 = .52, P < .01
N = 241 encounters, all data sources%
en
cou
nte
rs
Number of males in party
INTER-SITE DIFFERENCE IN AVOID RATE? controlling for number of males
Social cognitionChimpanzee cultures
Cognition,Culture
&Capuchins
Cebus apella
Brown capuchin
Capuchins:
• 3-4 kg
• males 25-30% larger than females
• multi-male, multi-female social groups
• high EQ (and are tool users)
• “eclectic omnivores” 40-60% fruit, 5-10% leaves, 20-55%
insects, plus a wide range of vertebrates that are hunted
opportunistically.
• known to use tools both in captivity and in the wild
• start to breed late and reproduce slowly for their body size (age
at first birth= 7, IBI=2 years) maybe related to their large brain
size
• vulnerable to predation by snakes, eagles and cats
Cebus capucinusCebus olivaceus
Cebus apella
Cebus albifronsClosely related to squirrel monkeys (Saimiri)
Cebus apella
Cebus albifrons
New species in BrazilBearded capuchin monkeys, Cebus libidinosus www.ip.usp.br/ebottoni/EthoCebus/ecspec.htm
New species in BrazilYellow-breasted capuchin, Cebus xanthosternos
www.waza.org/virtualzoo/factsheet.php?id=106-006-007-002&view=Monkeys&main=virtualzoo
F-F relationships
• Females are philopatric
• Stable, nepotistic dominance hierarchy
• F groom other F > F groom M = Female-bonded social system
• F form coalitions with each other that can be very stable over time, and appear to be effective in competing with M
• all F allonurse, but high ranking F < low ranking F
M-M relationships
• clear alpha-M but no obvious dominance relationships among subordinates
• alpha-M is spatially central to the group
(anti-predator strategy?) • alpha-M monopolizes matings in Cebus apella, but not in the gracile capuchins
• alpha-M forms coalitions with the subordinate males in the group, and prevents subordinates from forming coalition with each other• males cooperate in defense against predators and non-group males in gracile capuchins (but not Cebus apella)
• in C. capucinus, males never refused solicitations for coalitional support in the context of intergroup interactions
• male C. capucinus actively search for lost group-mates
M-F relationships
• alpha-F ranks immediately below the alpha-M in all species except C. capucinus, where all females are subordinate to all males.• alpha-M requires the coalitional support of F in their group to maintain their rank (C. capucinus)
• F are hypothesized to receive protection from infanticide from the males in their group
Intergroup interactions
• almost always aggressive
• M are primary participants, F rarely
participate (and only if don’t have an infant)
• M form coalitions during intergroup
interactions (except in C. apella)
• lethal, coalitionary intergroup aggression has been seen
• extra-group males may be infanticidal
• In C. olivaceous, large groups displace small groups at feeding
sites, and the females in large groups have higher reproductive
rates.
Cebus olivaceus
Wedge-capped capuchin
Female-bonded
Female-philopatric
All males emigrate
Female rank clear
Daughters inherit rank
Lifespan to 36 years
First birth at 6 years
Cebus olivaceus
Wedge-capped capuchin
Allomaternal nursing
a. Infants
Group-wide
Rank-independent
Clearly affiliative
b. Juveniles or adult females!
High-rankers take
Low-rankers give
Clearly agonistic
Cebus olivaceus
Size fluctuations and persistence
length of eight matrilines in Main
Group over the period 1977-99,
sorted by decreasing matrilineal
dominance rank.
Valderrama et al. (2003)
alpha beta
lowest
What are the social-cognitive consequences of variation in brain size?
Rilling & Insel, 1999
Chimpanzee Capuchin
Hunt / meat-eat Yes Yes
Tool use Yes Yes
Lethal aggression Yes Some
Visual perspective-taking1 Yes No
Tradition Yes Yes
1 Visual perspective taking is one of the cognitive capacities associated with Theory of Mind, which is the ability to understand that other individuals have their own goals and intentions.
Cognition (Strier)1) Learning / imitation (development)
2) Ecological intelligence
Spatial memory
Tool use
Traditions
3) Social intelligence
Alliances
Tactical deception
Perspective-taking (TOM)
4) Implications for ethics
The “Social Brain” hypothesis: are big-brained species socially adept?
Dunbar, 1992; 1993
Conspecifics are competitors
Group living aggravates competition
Selective advantage to individuals successful in inter and intra group competitions
Social problem solving abilities (social cognition) predicted as target of selection
Mean social cognitive ability increases
Social Intelligence Hypothesis: Runaway directional selection for social cognition in primates
Guts are small
(1) Big-brained species: good at signing
(2) Big-brained species successful: mirror test
(3) Big-brained species: many traditions
Ant-fishing Camponotus
Gombe
Tai
Bossou
Mahale-K
BudongoMahale-M
Kibale
Gombe
ALL TRADITIONS
0
5
10
15
20
25
30
35
40
0 5 10 15 20 25 30 35 40
Kibale
Tai
Bossou
Mahale-M
Mahale-K
Budongo
YEARS OF STUDY
All wild chimpanzee populations have traditions
still rising !
Social transmission?
Ant-fish: Mahale, not Gombe
Communication
Hunting
Tai
Bossou
Gombe
Mahale
BudongoKibale
Gombe
0
5
10
15
20
25
30
0 5 10 15 20 25 30 35 40
Kibale
Tai Bossou
Mahale-M
Mahale-KBudongo
Years of Study
Numberof
toolsobserved
ALL TOOLs
All populations use tools...Leaf-grooming
Budongo
TaiBossou
Gombe
Mahale-K
KibaleMahale-M
Gombe
0
2
4
6
8
10
12
0 5 10 15 20 25 30 35 40
Kibale
Tai
Bossou
Mahale-M
Mahale-K
Budongo
Years of Study
AllCustomaryor Habitual
Food-Tools
… but not all use tools for food
KIBALE
BUDONGO
GOMBE
MAHALE
MT ASSIRIK
LOPÉ
BOSSOU
TAI
Patterns of diffusion
NUT-SMASH
Present
Absent (but nuts present)
CULTURAL DIFFUSION
Cultures
Mer
cade
r et
al (
2002
) S
cien
ce
BRUSH-STICK
Present
Absent (but eat termites)
CULTURAL DIFFUSION
LEAF-CLIP: LIMITED DIFFUSION?
Present
Absent
To leaf clip, a chimpanzee gathers one to five stiff leaves and bites little bits off with its front teeth without eating the leaves. The biting produces a distinctive ripping sound, which appears to be the goal. At Mahale Mountains National Park, young male chimpanzees and adult female chimpanzees that are ready to mate make the clipping sounds to attract each other's attention. The sound might be translated as meaning, "I would like to mate."
Present
Absent
PENIS-WIPE: LIMITED DIFFUSION?
In penis cleaning, leaves are
employed as ‘napkins’ to
wipe clean the penis after sex.
Twig, Kanyawara, Feb. 2005
Present
Absent
LEAF-GROOM: LIMITED DIFFUSION?
Kanyawara, Feb. 2005
HAND-CLASP GROOM
Present
Absent
HAND-CLASP GROOMING:DIFFUSION OR RE-INVENTION?
Never. GombeBossou
Budongo
Daily. Kibale, Mahale
Tai: died out!
Population variation:
Due to opportunities for
transmission?
Van Schaik et al (2003) Science
Primate traditions
Chimpanzees >> bonobos (mysterious)
Orangutans few >> gorillas
Capuchins few
Gorilla at Mbeli Bai Nouabalé-Ndoki National Park
1. Do primates know that others can perceive things differently?
Does she see something that I do not?
Yes:
(A) monkeys/apes follow the gaze of conspecifics
Tomasello, Call, Hare 1998
Adults inhibit gaze response to a human who repeatedly looks at nothing
Tomasello, Hare, Fogleman, 2001
(B) Gaze-response adapts to context
(C) Chimpanzees move around visual barriers blocking their view of another individuals gaze
Tomasello, Hare, Agnetta, 1999
•Two subjects compete for food
• Each subject held in an outside cage in a row of three adjacent cages •center cage baited with one or two pieces of food
• food baited different ways
• competitors released into middle cage to retrieve food
(2) Can primates use knowledge of what others perceive when competing over food?
Do subordinates prefer to approach and retrieve food that dominants cannot see?
Hare et al (2000, 2003) Anim Behav
NOYES
Subordinates approached
less when dominant was
informed
Subordinates retrieved more
food when dominants
uninformed or misinformed
Food retrieval
No approaches
Chimpanzee Cultures: New findings from Kibale
Sonya Kahlenbergwith chimpanzeeTease-toy
The Meaning of Weapon Invention
Imoso - alpha male since 1997
“Ah! We must now redefine man, redefine tool, or accept chimpanzees as humans.”
Louis Leakey, 1960.
Termite-fishing
Modifying tool
CULTURAL EVOLUTION DOES NOT DEPEND
ONLY ON INVENTION
FREQUENT INVENTION, FREQUENT EXTINCTION
CLUB USE BY CHIMPANZEES
‘To the Rescue’
O.C. Vane
A mid-Victorian tale
BARBARA (10 yrs) Throw at mangabey
Beat chimpDisplay/throw
AGGRESSIVE STICK USE BY KANYAWARA CHIMPANZEES 1997-2002
1997 1999 20011998 2000 2002
+ otherstick use?
JOHNNY7/14
TWIG YOGI LBSTOUT KAKAMA (x2)7/15
IMOSO7/09
XylocopaApis
HONEY STICK USE BY KANYAWARA CHIMPANZEES
1997 1999 20011998 2000 2002
+ otherstick use?
MAKOKUROSA
STOUT
“To understand the socioecological factors
that promote social learning in an evolutionary
perspective, it is necessary to look beyond the
great apes.” Perry et al. 2003, p. 242
But do socioecological factors promote social learning?
Ha: SL is adapted to specific social ecology
Hb: SL is an incidental consequence of cognitive ability