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A Cross-Species Comparative Study:
Grooming Patterns in Captive Populations
of Hamadryas Baboons and Geladas
Raymond Chiu Leong Ho
Queens College, City University of New York
June, 2009
Senior Honors Thesis
Submitted in partial fulfillment of the requirements for a
Bachelor of Arts with Thesis Honors in Anthropology
from Queens College, City University of New York.
Supervised by Dr. Larissa Swedell
Readers:
Dr. Sara Stinson
Dr. Ekaterina Pechenkina
Instructor: _________________
Date: _________________
Ho 2
Abstract
Primates groom themselves (autogrooming) and each other (allogrooming) for a variety
of purposes. Allogrooming is arguably an altruistic behavior, and may be explained by kin
selection. The purpose of this study is to better understand the grooming patterns of captive
hamadryas baboons (Papio hamadryas hamadryas) and geladas (Theropithecus gelada) within
the context of kin selection theory, which posits that kin will interact, especially in altruistic
ways, more than non-kin.
This study hypothesizes that grooming patterns in hamadryas baboons and geladas can be
explained by the patterns of philopatry, dispersal, social system and bonding that are seen in wild
populations. The results of this study show that there is a higher frequency of allogrooming than
autogrooming in both hamadryas baboons and geladas. It also shows that gelada leader males
groomed their females more than hamadryas leader males groomed their females, which does not
support the hypothesis of this study. The following results showed a trend but were not
statistically significant enough to support the hypotheses: female hamadryas baboons and
geladas groomed more than male hamadryas baboons and geladas; hamadryas leader males
groomed their females more than females groomed among themselves in the same hamadryas
group; gelada females groomed each other more than gelada leader males and their females;
male hamadryas baboons groomed more than male geladas; female geladas groomed more than
female hamadryas baboons; hamadryas baboons groomed more than geladas.
In addition, this study also hypothesizes that there is a correlation between grooming
frequency and temperature. There is a positive correlation between grooming frequency and
temperature in hamadryas baboons but a negative correlation in geladas.
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Introduction
Grooming is the bond that holds primate sociality together. In this study, I compare
grooming frequencies between captive populations of hamadryas baboons (Papio hamadryas
hamadryas) and geladas (Theropithecus gelada) in zoological parks. I test the hypothesis that
grooming patterns in hamadryas and gelada baboons directly reflect their bonding patterns and
social systems.
Grooming
Grooming is an action by which animals clean their skin, fur or feathers to remove dirt
and ectoparasites from themselves or from others. Across the animal kingdom, grooming is
prevalent and can be found in most taxa. Grooming helps get rid of scabs, parasites and food
particles that are stuck on an individual's hair, fur, feather or skin (Falk, 2000; Nunn and Altizer,
2006; Samish and Rehacek, 1999). At first glance, grooming serves a hygienic function or
reduces the risk of disease, but several studies have shown that grooming serves a variety of
other purposes.
The function of grooming underwent an evolutionary change, altering its function from
simple hygiene to, among other things, social bonding (Kummer, 1995). In addition to removing
ectoparasites and lowering the risk of disease (Falk, 2000; Nunn and Altizer, 2006; Samish and
Rehacek, 1999 ), grooming can also serve to strengthen social bonds (Kummer, 1995; Waldman,
1988; Falk, 2000; Nunn and Altizer, 2006; Dunbar, 2008; Di Bitetti, 1997), reduce tension (Judge
et al., 2006), calm (Falk, 2000; Colmenares et al., 2002), soothe (Falk, 2000; Colmenares et al.,
2002 ), appease (Falk, 2000), reassure (Swedell, 1997), reconcile after an aggressive interaction
(Swedell, 1997), gain favor with more dominant individuals (Kummer, 1995; Falk, 2000; Schino
and Aureli, 2008) or indicate sexual receptivity (Falk, 2000, Morris and Bruce, 2005). Dunbar
(2008) suggests that the major reason for grooming is the satisfaction of physical contact
between the groomer and the individual being groomed. One of the functions of social grooming
in birds and mammals is to reinforce friendly relationships (Parker and Jaffe, 2008).
Grooming can be categorized into self grooming (autogrooming) and social grooming
(allogrooming). Self grooming or autogrooming is defined as a grooming activity done by an
individual to itself. Autogrooming can be observed in both social groups and in solitary
individuals. It is important to note that autogrooming is not a behavior ascribed only to solitary
individuals. Adaptations for autogrooming such as dental combs and toilet claws in strepsirhines
help groom areas that are hard to reach, for example the animal's back or the back of their head
(Henzi and Barrett, 1999; Falk, 2000).
Social grooming or allogrooming is defined as a grooming activity between individuals.
The difference between autogrooming and allogrooming is that the former lacks the element of
sociality. As the name indicates, allogrooming is a form of grooming where one individual
grooms another in a social context. Social grooming tends to be a reciprocal interaction and it
involves more than one individual.
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Allogrooming can be a dyadic or sometimes a triadic interaction. Dyadic grooming is
grooming between two individuals, also known as a dyad. Grooming interaction between a
groomer and an individual being groomed is then called a dyadic interaction. According to
Dunbar (1984), two individuals who spend more than 10% of their potential social time
grooming can be referred to as grooming partners or a grooming dyad. Grooming among three
individuals, also known as a triad, is called triadic grooming. Interaction between two groomers
and an individual being groomed is call a triadic interaction. Most allogrooming involves a
dyadic interaction, but triadic interactions are not rare.
Studies have shown that allogrooming is not at all unique to primates but is also observed
in other taxa. Allogrooming is also observed in other mammals, insects, reptiles and birds.
Impalas (Aepyceros melampus) groom each other; in particular, it is very common for impala
fawns to groom their mothers (Mooring and Hart, 1995). Honey bees (Apis mellifera) have been
observed grooming each other to remove pollen grains from their wing bases (Morris and Bruce,
2005). European green lizards (Lacerta viridis) also groom each other routinely (Morris and
Bruce, 2005). Allogrooming or allopreening in Green woodhoopoes (Phoeniculus purpureus) has
also been observed and is thought to have hygienic and social functions (Radford and Du Plessis,
2006).
For allogrooming to occur on a reciprocal basis, an individual must have the ability to
recognize its grooming partners, have long-term memory to remember who its grooming partner
is and be willing to reciprocate. Reciprocity of social grooming creates a platform of trust
between grooming individuals (Dunbar, 2008). Allogrooming is usually regarded as an altruistic
act because individuals seemingly sacrifice their foraging time and predator vigilance to groom
each other.
Altruistic behaviors are those that potentially reduce the fitness of the actor while
enhancing the fitness of the recipient. While impalas groom each other, they let their guard down
against potential predators, a classic case of altruism (Mooring and Hart, 1995). The question is
then why these individuals still groom each other if they have a higher chance of being preyed
upon.
We can explain most altruistic behavior through kin selection. A theory put forth by W.D.
Hamilton, kin selection may occur when the benefit of an altruistic act by an actor towards kin
outweighs the actor's cost, thereby increasing the inclusive fitness of the actor (Falk, 2000). The
key element for kin selection to work is the relatedness between the actor and the recipient. The
higher the relatedness, the greater the benefit-cost ratio and the potential for kin selection to
occur.
As predicted, allogrooming tends to be kin-biased which reinforces the idea that it is an
altruistic act (Falk, 2000; Waldman, 1988). Research shows that honey bees prefer to groom full-
sisters rather than half-sisters (Waldman, 1988). We can expect to see a higher frequency of
social grooming between close kin than between those that are not related to each other
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(Waldman, 1988). Allogrooming is prevalent in primate societies and several studies have shown
that primates groom their kin more frequently than other members of the same troop (Waldman,
1988).
Grooming in primates
Most primates are social, and grooming is common in these gregarious animals (Falk,
2000). Grooming is one of the major behavioral elements in primate sociality (Dunbar, 2008). In
fact, social grooming in primates is sometimes referred to as the cement of primate social life
(Falk, 2000). Grooming behavior in captivity is an example of why grooming does not occur
solely to get rid of ectoparasites. Wild primate populations do not suffer from as many
ectoparasites as previously thought and are expected to suffer even less while captive in
zoological parks (Franz, 1999). Despite this, captive primates still spend a large amount of time
grooming themselves and each other.
All prosimians have toilet-claws, specialized toenails that are used in autogrooming
(Falk, 2000; Soligo and Müller, 1999). Dental combs found in strepsirhines help facilitate
grooming as well, especially in solitary nocturnal species that do not gather in social groups such
as galagos and lorises (Dunbar, 2008). Dental combs are used for autogrooming by these solitary
animals. However, dental combs also play a vital role in allogrooming in non-solitary lemur
species such as the ring-tailed lemurs, Lemur catta (Morris and Bruce, 2005; Nunn and Altizer,
2006; Dunbar, 2008). Aside from grooming purposes, Falk (2000) also suggests that tooth combs
and toilet claws evolved in primates to apply and distribute scent to the owner's fur.
Haplorhines have dexterous fingers with superb fine motor skills. They also have
opposable thumbs that allow them precise, powerful grips (Falk, 2000). This allows them to use
the pincer grasp, the grasping of an object between the thumb and fingers, when grooming
themselves or others (Dunbar, 2008). Groomers use their hands to pick through hair to remove
bits of debris, which they sometimes eat (Falk, 2000).
In baboon groups, Jorde and Spuhler (1974) found a negative correlation between time
spent foraging and time spent engaging in social activities, such as grooming. Groups that spent
less time foraging for food spent more time engaging in social activities. Lehmann et al. (2007)
showed that there are several variables that affect time spent grooming in primate groups: group
size, dispersal patterns and sex ratios. However, they did not find a correlation between time
spent grooming and group size in the taxa Papionini, which includes hamadryas and gelada
baboons (Lehmann, 2007). There is, however, a correlation between time spent social grooming
and group size, but not body size, across Old World Monkeys as a whole (Leinfelder et al., 2001;
Nunn and Altizer, 2006). The larger the group size, the more time they are expected to groom
each other.
Hill (2006) stressed that thermoregulation and temperature are important ecological
variables to consider when studying primate behavior. He found that there is a correlation
between temperature and time spent grooming (Hill, 2006). As temperature increases, baboons
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spend more time grooming each other instead of foraging for food (Hill, 2006).
After observing the disproportionate grooming frequency between female olive baboons
(Papio anubis) and their dominant partners compared to lower ranking individuals, Seyfarth
(1976, 1977) proposed that social grooming is a form of reciprocal altruism (Matheson and
Bernstein, 2000). He suggested that females groom higher-ranking individuals because they
expect agonistic aid from these individuals in the future (Matheson and Bernstein, 2000).
Reciprocal altruism can be best described as a “tit-for-tat” strategy.
Within the framework of a game theory model named the Prisoner's Dilemma, a “tit-for-
tat” strategy states that if individuals encounter each other only once, then it pays to cheat
(Barrett et al., 2002). However, if individuals encounter each other frequently then it pays for
them to cooperate with each other (Barrett et al., 2002). Outlined by Axelrod in 1984, the “tit-
for-tat” strategy was modeled in a repeated Prisoner's Dilemma (Barrett et al., 2002). This
strategy has two simple rules based on reciprocity between individuals (Barrett et al., 2002).
Individuals must cooperate on the first move and then, on each succeeding move, do whatever
their opponent did in the previous move (Barrett et al., 2002). So, in grooming dyads,
individuals start by grooming their partner and will continue to groom them if they themselves
receive grooming in return. If an individual does not cooperate to return the grooming to their
partner, then their partner “retaliates” by not grooming the individual back. However, part of the
tit-for-tat strategy is that if an individual defects and then cooperates on the next move, their
partner will cooperate instead of continuing to retaliate (Barrett et al., 2002). The tit-for-tat
strategy is said to be “forgiving” because it is capable of setting up a long cooperative interaction
instead of a self-defeating defection (Barrett et al., 2002). Once established in a stable
population, the tit-for-tat strategy cannot be replaced by other strategies (Barrett et al., 2002).
This is known as an Evolutionarily Stable Strategy (Barrett et al., 2002).
The Seyfarth hypothesis predicts the attractiveness of individuals based on their
dominance rank; the higher their rank, the more attractive they are as grooming partners (Franz,
1999). A study by Franz (1999) on allogrooming in bonobos (Pan paniscus) showed that there is
a grooming preference for those that are higher-ranking. It supports the hypothesis that higher-
ranking individuals are the most attractive grooming partners. A study by Schino (2007) on 14
primate species also showed that there is a positive correlation between grooming and agonistic
support, which reinforces the reciprocal altruism claim.
However, Matheson and Bernstein (2000) found no evidence for competition to groom
high-ranking individuals in Rhesus monkeys (Macaca mulatta). They argued that the pattern of
grooming is best associated with the strength of social relationships rather than competition to
groom higher-ranking partners (Matheson and Bernstein, 2000). Grooming interactions among
geladas do not necessarily correlate with dominance rank (Dunbar, 1982). Female grooming
dyads are usually kin-based, with mothers and daughters often forming grooming pairs (Dunbar,
1984; Dunbar, 1982). Hamadryas baboons, however, groom more dominant individuals to gain
favor (Kummer, 1995). According to Kummer (1995), hamadryas baboons in the Zürich Zoo
groomed the hair of their leader male, Pasha, in order to receive agonistic support.
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A study by Manson et al. (2004) on bonnet macaques (Macaca radiata) and white-faced
capuchins (Cebus capuchinus) showed that grooming among females is time-matched in female-
bonded societies. Time-matching occurs when both grooming partners receive approximately the
same grooming time as they performed on their partner (Manson et al., 2004). Allogrooming in
tufted capuchin monkeys (Cebus apella) shows that dominant individuals, particularly females,
groom more frequently than those that are lower in the dominance rank (Di Bitetti, 1997; Parr et
al., 1997). Females also tend to groom each other and reciprocate more than males (Di Bitetti,
1997). Alpha females, not low-ranking females, receive less grooming in tufted capuchin
monkeys (Parr et al., 1997). Alpha females groom lower-ranking females more, indicating that
tufted capuchin monkeys groom down the hierarchy as opposed to most primates that groom up
the hierarchy. Preference for grooming higher-ranking individuals thus does not seem to be a
universal trait for primates.
Papionini
Hamadryas and gelada baboons are Cercopithecidae, commonly known as the Old World
Monkeys (Falk, 2000). They belong to the subfamily Cercopithecinae or “cheek-pouched
monkeys” (Falk, 2000). Both hamadryas baboons and geladas are in the taxonomic tribe
Papionini, which also includes the genera Macaca, Cercocebus, Lophocebus and Mandrillus
(Whitehead and Jolly, 2006). Hamadryas baboons belong to the genus Papio while geladas
belong to the genus Theropithecus. Hamadryas and gelada adult males are easily distinguishable
from females because they have manes that run from their head to their shoulders. Jolly (1963)
suggests that the mane in hamadryas baboons is due to both intrasexual and intersexual selection.
It acts to intimidate other males and proves irresistible to the females. The evolution of manes in
male geladas is probably due to the same sexual selection pressure as male hamadryas baboons.
Grüter and Zinner (2004) believe that ancestral hamadryas baboons and geladas used to live in
multi-male and multi-female societies before splitting into one-male unit social systems. Using
socio-ecological models to look at the evolution of primate social systems, they believe that
ecological factors and risk of predation played an integral role in shaping the social system of
hamadryas baboons and geladas (Grüter and Zinner, 2004).
Hamadryas Baboons
Hamadryas baboons (Papio hamadryas hamadryas) live in the arid sub-desert and the
savanna woodlands of Ethiopia, Eritrea, Somalia, Yemen and Saudi Arabia (Swedell, 2002b;
Winney et al., 2004; Shefferly, 2004: Hiller, 2000). Hamadryas baboons are the only non-human
primate found in Saudi Arabia and are believed to have reached Arabia through the southern Red
Sea when land bridges were formed during glaciation (Winney et al., 2004). There has not been
any gene flow between the African population and the Arabian population after the land bridges
submerged around the southern Red Sea area (Wildman et al., 2004). Due to their dry and arid
habitat, hamadryas baboons are often referred to as desert baboons, distinguished ecologically
from other members of the genus Papio such as the savanna baboons and the mountain baboons
(Swedell, 2002b). These baboons were once considered sacred by the Egyptians because they
were thought to be the attendant of the gods and a symbol of Thoth, the god of scribes, earning
Ho 8
them the name “sacred baboons” (Falk, 2000). They are diurnal animals and are adapted for a
variety of locomotion, including terrestrial quadrupedalism and arboreal quadrupedalism and
climbing (Swedell, in press; Kummer, 1971).
Hamadryas baboons have a prognathic muzzle with a pink face (Swedell, in press). Adult
male and female hamadryas are highly sexually dimorphic (Shefferly, 2004). Adult males are
silvery gray while females and juveniles range across shades of brown (Swedell, in press). The
pelage of a newborn is black, gradually turning to brown as it matures (Swedell, in press;
Shefferly, 2004). Males have silvery whiskers and a silvery mane around their shoulders while
females lack whiskers and mane (Swedell, in press). In both sexes, the paracallosal skin (lateral
to the ischial callosities) is pink to bright red (Swedell, in press; Shefferly, 2004). Females
exhibit sexual swellings during estrus (Swedell, in press). A red swollen rump is a signal that the
female is in estrus and ready to mate (Swedell, in press). Males have longer and larger canines as
a result of competition among males, also known as intrasexual selection (Leigh et al. 2005). An
adult hamadryas male can weigh around 47.3 lbs and a female around 20.24 lbs., about half the
size of a male (Shefferly, 2004). In captivity, hamadryas baboons live about 20 years and some
live over 30 years (Swedell, in press). However, longevity in the wild is unknown (Swedell, in
press), but is probably less than 20 years.
Hamadryas baboons are generalist omnivores (Swedell et al., 2008). They feed on leaves,
grass, seeds, roots, tubers and animal prey such as insects and small mammals (Swedell et al.,
2008). In a diet composition study, a total of 41 plant species were consumed by a band of
hamadryas baboons in Filoha, Ethiopia (Swedell et al., 2008). From their resting site, hamadryas
troops disperse across the countryside during the day and then break into smaller groups to feed
and forage (Kummer, 1968). Due to scarcity of food resources, it is vital for them to break into
small groups to find enough food to eat (Falk, 2000). Hamadryas baboons have a relatively large
home range. Swedell (2002b) reported that the estimated home range for her Filoha hamadryas
group is 30 km2.
Hamadryas baboons live in a multi-level social system (Kummer, 1995; Falk, 2000;
Swedell, 2006; Swedell et al., 2008). Their social structure consists of multiple levels; the clan,
the band, the troop and the one-male unit (OMU) (Kawai et al., 1983; Kummer, 1995; Falk,
2000; Swedell, 2006; Swedell et al., 2008). Several one-male units form a clan, while several
clans that forage together form a band (Swedell et al., 2008). Due to scarcity of cliffs where
hamadryas spend the night, bands of hamadryas baboons congregate together to form a troop,
sometimes up to 750 individuals, sharing the same sleeping site (Falk, 2000). Hamadryas
baboons live in a patrilineal society. Males are philopatric while females disperse from their natal
bands (Falk, 2000). Because of that, males tend to be more closely related than females.
Takeovers happen when a leader male of a OMU is being displaced by another male.
Reports of infanticide after takeovers are not uncommon (Swedell and Tesfaye, 2003). The
sexual selection hypothesis predicts that after takeovers, new leader males would benefit from
killing his female's infant so that she goes back into estrus soon to maximize his fitness (Swedell
and Tesfaye, 2003). Swedell and Tesfaye (2003) found that new leader males will only kill
infants who are sufficiently young, to expedite the mothers going back into estrus.
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Hamadryas baboons are behaviorally different than other mammals; males physically
coerce females into semi permanent social units call the OMU (Swedell and Schreier, 2009).
Social bonds within hamadryas baboons OMU are often referred to as representing a “star-
shaped sociogram” (Swedell, 2002a; Grüter and Zinner, 2004; Swedell, 2006). The strongest
bond in a OMU is between the leader male and his females (Swedell, 2002a). Bonds among
females in the same OMU are weaker by comparison (Swedell, 2002a). A hamadryas male
sociogram is more centripetal; he is the focus of all his females (Grüter and Zinner, 2004). Male-
male bonding is stronger than female-female bonding in hamadryas baboons due to their
patrilineal society. However, Swedell (2002a) found that not all hamadryas baboons form a “star-
shaped sociogram”. Some females are actually “female bonded”, forming strong bonds among
females (Swedell, 2002a).
The hamadryas mating system is usually polygynous. A typical hamadryas OMU consists
of a male, about two to three females and their offspring (Shefferly, 2004). Within this OMU, the
single adult male mates with all his adult females (Shefferly, 2004). Subadult males, between the
ages of 8.5 and 11, may kidnap young females from another OMU to start a new one-male unit
and to mate (Falk, 2000). Males keep their females nearby with threats, sometimes even biting
their necks if they wander off or try to mate with another male (Falk, 2000). This herding
behavior is an outcome of competition from other males and functions to control female behavior
(Swedell and Schreier, in press). A bite behind the neck is a cue for the female to obey and return
to the leader male, a form of conditioning (Swedell and Schreier, in press; Swedell, 2006).
Grooming in Hamadryas Baboons
Kummer's (1968) observations show that grooming in female hamadryas is focused on
their leader male and their offspring. Grooming among females is uncommon with the exception
of mother and daughter interaction (Kummer, 1968). Kummer (1968) concluded that the lack of
grooming among females is due to the leader male, who does not tolerate females from the same
OMU grooming each other.
Kummer (1968) and Swedell (2002a) also found that there a negative correlation between
total time spent grooming and number of individuals in a OMU. The total time spent grooming
between a leader male and his females increases as the number of females decreases in the
OMU. When the number of females increases in a OMU, total time spent grooming between a
leader male and his females decreases.
However, observations from the Filoha hamadryas troop by Swedell (2006) show that
only half of the females groomed their leader male more than they groomed other females. In
other words, half of the females spent as much or more time grooming other females in the OMU
compared to their leader male (Swedell, 2002a; 2006). The frequency of grooming among
females is higher than the frequency of grooming between mothers and their offspring (Swedell,
2006).
Judge et al. (2006) found that allogrooming acts as a tension-reduction strategy to cope
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with crowding in their captive hamadryas population. Females groom their leader male more
frequently during overcrowding, and this serves to lower aggression (Judge et al., 2006). Female
hamadryas baboons also appear to groom others in hopes that they themselves will be groomed
later (Leinfelder, 2001). Grooming reciprocity is higher between individuals in the same
grooming dyad compared to individuals that are not grooming partners (Leinfelder, 2001).
Geladas
Geladas (Theropithecus gelada) were once widespread in Eastern and Central Africa but
are now isolated on the high plateau of North Central Ethiopia and Eritrea (Hiller, 2000; Dunbar
and Dunbar, 1975). Their habitat consists of slopes of steep sided grasslands at altitudes of no
lower than 1500 m, where temperatures range from 60 degrees during the day to below freezing
at night (Hiller, 2000; Dunbar, 1984). Geladas from Dunbar's (1984) study site live in high
altitude at about 3300 m in Sankaber, Ethiopia. Geladas are diurnal and are adapted for terrestrial
quadrupedal locomotion though they usually shuffle themselves on their ischial callosities when
feeding (Hiller, 2000; Dunbar, 1984).
Geladas are sometimes referred to as “bleeding heart monkeys” due to the presence of the
naked, pink patches of skin on the chests of males and females (Dunbar and Dunbar, 1975). In
males, the patch of skin could be triangular or heart-shaped (Dunbar, 1984). In females, it is
heart-shaped surrounded by vesicles that look like a pearl necklace (Dunbar, 1984). Both males
and females have hollow cheeks, a little turned-up nose and grooves along the sides of the
projecting rounded muzzle (Dunbar and Dunbar, 1975). Geladas are highly sexually dimorphic;
males are about double the size of females and have a mane (Hiller, 2000; Dunbar and Dunbar,
1975). Males can grow up to about 46 lbs. while females can reach to about 29 lbs. (Hiller,
2000). Geladas have a maximum lifespan of about 19 years in the wild (Falk, 2000) and well
over 30 years in captivity (Hiller, 2000). Both males and females have thick brown coats on their
body as an adaptation to living in cold environment.
Geladas are gramnivores. They are unique among primates because the majority of their
food source consists of grass and is occasionally supplemented by seeds, roots, and bulbs
(Dunbar, 1984). During the day, geladas spend most of their time grazing, sometimes in groups
of over 400 individuals. They shuffle around on their ischial callosities, picking up blades of
grass to eat. The home range of geladas is about 72.5 km2 (Dunbar, 1984). A study by Iwamoto
and Dunbar (1983) on geladas showed that there is a positive correlation between altitude and
time spent foraging; more energy is burnt at higher altitudes thus more time is spent on feeding.
This indirectly affects the allocation of social time, especially grooming (Iwamoto and Dunbar,
1983).
In geladas, males do not herd or bite the neck of a female; instead, the alpha female
maintains group cohesion (Dunbar, 1984). When fearful, nervous or intimidated, geladas retract
their scalp, revealing patches of white above the eyes. In the meantime, the upper lip is turned
inside out and flipped over the nose. This “lip-flip” behavior is unique to geladas (Estes, 1991).
Ho 11
Like hamadryas, geladas are characterized by a multi-level social system (Kummer, 1971;
Dunbar, 1984). They have a four-tiered social structure (Kawai et al. 1983) and share sleeping
sites, just like hamadryas (Dunbar, 1984). Generally, about 10 to 15 individuals can be found in
an OMU (Dunbar, 1980). Geladas live in a matrilineal society as opposed to that of a patrilineal
hamadryas society. Female geladas are philopatric while males disperse from their natal group
(Falk, 2000). Because of this, females tend to be more closely related than males.
Social bonds in geladas occur mainly in females. The strongest bond in a gelada OMU is
that among females. Bonds between the leader male and his females are relatively weak, and the
leader male is socially more peripheral (Grüter and Zinner, 2004; Bramblett, 1970).
Relationships between males and females are generally weaker than those in hamadryas and tend
to occur only when females are in estrus (Dunbar, 1984; Dunbar and Dunbar, 1975). This is true
in geladas and most baboon species, except in hamadryas where male and female bonds are the
strongest (Swedell, 2006).
The gelada mating system is polygynous. When a female is in estrus, her heart-shaped
skin patch turns bright red and the surrounding vesicles swell, mimicking the similar swelling in
her genitalia (Dunbar and Dunbar, 1975). This trait might have evolved as an adaptation to
spending a large amount of time shuffling on their ischial callosities while feeding (Dunbar and
Dunbar, 1975). Female geladas use their chest to convey sexual receptivity while female baboons
use their rumps (Falk, 2000; Dunbar, 1984; Dunbar and Dunbar 1975).
Grooming in Geladas
Grooming in geladas generally occur among adults of the same OMU and never among
individuals from different OMUs (Kawai, 1979). Kawai (1979) found that the leader male and
the alpha female of the OMU tend to have a strong grooming relationship. He also found that this
relationship changes slightly when the other females are in estrus (Kawai, 1979). The alpha
female will attempt to stop the leader male from grooming the other females that are in estrus
(Kawai, 1979). It is up to the alpha females whether they want to monopolize the leader male or
let him groom his other females that are in estrus (Kawai, 1979).
However, according to Dunbar (1984), the leader male does not groom his females more
when they are in estrus. Also, he found that grooming between a leader male and all of his
females rarely follows copulation except with his main female, which tends to be the alpha
female (Dunbar, 1984). Gelada females prefer to groom their mature daughters and also have a
tendency to form grooming relationships with other females (Dunbar, 1982; Dunbar, 1984).
These grooming dyads are matrilineal in origin, as gelada females in the same OMU are all
related (Dunbar, 1982).
HYPOTHESES
Hamadryas baboons and geladas live in large complex social groups. Grooming is used
for many purposes. We can expect a high frequency of grooming, specifically allogrooming,
Ho 12
among primates that live in large complex social groups such as hamadryas and geladas. Thus,
we expect a higher frequency of allogrooming compared to autogrooming in both hamadryas and
geladas.
Male hamadryas are philopatric whereas female hamadryas disperse from their natal
group. Therefore, we can expect that the degree of relatedness among males in a troop is higher
than among females of the same troop. Male-male bonds are stronger than female-female bonds
in a hamadryas patrilineal society. Hamadryas have a one-male multi-female social system, or a
one-male unit (OMU). Bonds between the leader male and his females in a OMU are the
strongest while bonds between females in the same OMU are the weakest. Therefore, I expect
there to be a higher frequency of grooming among hamadryas males than among females. Also,
the frequency of grooming between the leader male and his females should exceed that of
grooming among females in the same OMU.
In geladas, however, females are philopatric while males disperse from their natal group.
The degree of relatedness between females is higher than the degree of relatedness between
males in a gelada troop. Therefore, female-female bonds are stronger than male-male bonds in a
gelada matrilineal society. Geladas also live in one-male multi-female social units, or OMUs.
Bonds among females in a OMU are the strongest. Bonds between the leader male and his
females in the same OMU are the weakest except the bond between leader male and the alpha
female. Therefore, I expect there to be a higher frequency of grooming among gelada females
than among males. Also, the frequency of grooming among females should exceed that of
grooming between the leader male and his females in the same OMU.
In hamadryas society, male-female bonds are the strongest bonds. Male-male bonds are
weaker and female-female bonds are weakest. Comparatively, in geladas, female-female bonds
are the strongest bonds. Male-female bonds are weaker and male-male bonds are weakest.
Based on the patterns of philopatry, dispersal and bonding, I expect hamadryas males to
groom each other more frequently than gelada males. On the other hand, I expect female geladas
to groom each other more frequently than hamadryas females. I also expect more grooming
between the leader male and his females in a hamadryas OMU than in a gelada OMU.
According to Jorde and Spuhler (1974), there is a correlation between time spent foraging
and time spent engaging in social activities. Compared to hamadryas baboons, geladas spend
most of their day foraging for food, plucking blades of grass with their nimble fingers. Therefore,
if Jorde and Spuhler are correct, then I expect the frequency of grooming among hamadryas to be
greater than that of the geladas. Such a difference might not occur in captivity, however, where
food resources are similar between the two species.
Also, Hill (2006) inferred a correlation between temperature and time spent grooming. As
temperature increases, baboons spend more time grooming each other instead of foraging for
food (Hill, 2006).
Ho 13
Grooming patterns of captive hamadryas and gelada populations in zoological parks can
be predicted by using the same patterns of philopatry, dispersal and bonding that we see in wild
populations. We expect that these captive populations have the same patterns of bonding as those
from wild populations, as patterns of bonding result from individual motivations that likely hold
true in captivity. Therefore, we expect these hypotheses to still hold true:
1. I expect a higher frequency of allogrooming compared to autogrooming in hamadryas
and geladas.
2. I expect a higher frequency of grooming done by hamadryas males than by hamadryas
females.
3. I expect a higher frequency of grooming done by gelada females than by gelada males.
4. I expect a higher frequency of grooming between females and their leader male than
among females in the same hamadryas group.
5. I expect a higher frequency of grooming among females than between females and their
leader male in the same gelada group.
6. I expect hamadryas males to groom each other more frequently than gelada males.
7. I expect gelada females to groom each other more frequently than hamadryas females.
8. I expect a higher frequency of grooming between the leader male and his females in
hamadryas groups than gelada groups.
9. I expect a higher frequency of grooming in hamadryas compared to geladas.
10. I expect hamadryas baboons to spend more time grooming as temperature increases.
11. I expect geladas to spend more time grooming as temperature increases.
METHODS
Observations
Observations for this study began in October 2008 and were completed in April 2009. A
total of 50 hours of observation were conducted. To ensure that the data were representative
when I compared the two groups, I observed each for 25 hours. I also limited myself to a
maximum of 5 hours of observation per visit to make sure that the data collected were
representative of the animals' behavior throughout the 6 months of observation. Observations
Ho 14
were done behind the windows of the enclosures in both zoological parks during their open
hours, usually between 11am and 4pm.
Study Subjects
The hamadryas baboons are housed in the Animal Lifestyle building, an outdoor exhibit
at The Prospect Park Zoo. The enclosure mimics that of the hamadryas baboons' natural
environment, complete with rocky cliffs, small caves and waterfalls. Visitors can observe the
baboon troops in three indoor viewing areas behind glass. A small enclave on the side of the
exhibit connects to their indoor night enclosure. The hamadryas are given a choice to either stay
inside their night enclosure or come out to the exhibit during inclement weather.
The geladas at The Bronx Zoo are housed in an outdoor enclosure. The Baboon Reserve
is designed to replicate the rocky and grassy slopes of the African-alpine zone in the Ethiopian
Highlands (ZooLex, 2005). The gelada troops share their habitats with two Nubian ibex (Capra
ibex) during the cold season and also with a group of rock hyrax (Procavia capensis) when the
weather gets warmer. Two observation stations offer panoramic views of the gelada baboons,
from behind glass. The third observation area is outdoors amidst the African Market Plaza where
visitors can sit down on benches and buy refreshments and gifts (ZooLex, 2005).
The hamadryas baboons at The Prospect Park Zoo consist of two OMUs, H1 and H2
(Table 1). H1 consists of six individuals: a leader male (Ben), his female (Mimi) and his four
offspring (Fadi, Neji, Fifi and Ken). H2 consists of four individuals: a leader male (Leo) and his
three females (Jenn, Anne and Pam). Kummer (1968) provides a useful table for identifying the
sex and estimated age of hamadryas baboons. In addition, sex and ages of individual hamadryas
can also be obtained from The Prospect Park Zoo. For the purposes of my observation, I named
the individuals prior to receiving the names given to me by The Prospect Park Zoo. Table 2
shows the names given to the hamadryas baboons by The Prospect Park Zoo and the
corresponding names that I gave to them. During the course of study, all individuals were present
at the exhibit.
At The Bronx Zoo, the geladas consist of two OMUs, G1 and G2 (Table 3). G1 consists
of four individuals: a leader male (Patrick) and his three females (Lynne, Marie and Syndee). G2
consists of two individuals: a leader male (Bruce) and his female (Bonnie). Dunbar and Dunbar
(1975) provide a useful table for identifying the sex and estimated age of gelada baboons. Using
the table, I estimated the sexes and ages of the individuals. In addition to sexing and estimating
ages from Dunbar and Dunbar (1975), information on individual geladas can also be obtained
from The Bronx Zoo (though I was not able to obtain this information). Some gelada individuals
were very rarely present during my observations, especially in the winter.
The sample size for the hamadryas at The Prospect Park Zoo was 10 individuals. All
individuals were present during my observations between October 2008 and April 2009. The
sample size for the gelada troop during my observations at The Bronx Zoo was 6 individuals out
of the 9 individuals that are part of The Bronx Zoo's collection. During inclement weather or
Ho 15
when it was cold, not all individuals were on display. Only two OMUs were on display between
October 2008 and April 2009. Table 4 shows possible grooming dyads between the hamadryas
baboons at The Prospect Park Zoo while Table 5 shows possible grooming dyads between the
geladas at The Bronx Zoo.
Data Collection
A combination of point time sampling and focal animal sampling methods was used to
obtain data (Figure 1). Incorporating both methods of sampling allowed me to record the
behavior of a specific study animal (subject) at an assigned period of time between intervals
(Paterson, 2001). This combination allowed me to use a check sheet that represented the
behavior of a single subject at fixed time intervals. Each check sheet is 10 minutes long with 20
seconds intervals between recordings. At each sampling point, I recorded the subject's behavior
on the check sheet. Recording started at 0:00 minutes and ended at 10:00 minutes, yielding 31
points per check sheet. A stopwatch (Sport line, Model-220) was used so that data could be
recorded every 20 seconds. The stopwatch was also used to record the time of day when a given
sheet's observation started and ended.
Variables such as sex, weather, temperature, date and time were also recorded on every
check sheet. Average temperature readings for each observation day were obtained from The
Weather Channel website (1995) by averaging the highest temperature and lowest temperature of
the day. Temperature readings were recorded in degrees Fahrenheit (°F).
I used categories such as BZ (The Bronx Zoo), PPZ (The Prospect Park Zoo), G
(Geladas) and H (Hamadryas Baboons) so that the check sheets for the two study species would
be easily distinguishable from each other.
When starting observations for each check sheet, I chose a random individual so that an
equal distribution of data from different individuals (subjects) could be obtained. When a subject
was out of sight, I used Lehner's (1996) method of resolving that subject's behavior. In his
Handbook of ethological methods, he allocates subjects the same behavior they were doing
before going out of sight, if they are doing the same thing when they return. If, upon returning
into sight, the subject is doing something else, then it is recorded as “out of sight”. I applied this
rule only when the subject was locomoting before and after it went out of sight, because it would
be unlikely that a subject would engage in another activity in the middle of locomoting for a
minute or less. However, if the subject remained out of sight for more than one minute (10% of
the total check sheet time) then the check sheet was discarded. Another individual was chosen
and a new check sheet begun. This was done to ensure that data from the ethogram was
representative of the animal's behavior for the duration it was being recorded.
Data Analysis Methods
I converted the total points into percentage to compare budget allocation and grooming
between the two species. I found the mean of these percentages by summing them and then
Ho 16
dividing by the number of individuals. I then used these average values to compare grooming
differences by sex and by dyads. I tested the significance of the results for hypotheses 1 to 9 with
the Mann-Whitney (MW) Test using the StatCrunch online statistics program (StatCrunch,
2007). Using the Spearman's Rank Correlation Coefficient (SRCC) Test, I tested if a correlation
between temperature and frequency of grooming was statistically significant for hypotheses 10
and 11. For these two hypotheses, I used an online calculator from Free Statistics Software
(Wessa, 2009). All tests were one-sided (or one-tailed), and the P-value was set at 0.05.
Behavioral Categories
I grouped behaviors into exhaustive categories. Each behavior is mutually exclusive; no
more than one behavior from the subject was recorded at a time (Paterson, 2001). Here I list the
behavioral categories and their definitions from the check sheet:
1. Locomoting (L): When a subject is moving from one location to another. Any form of
locomotion done by a subject falls under this category.
2. Resting (R): When a subject is not moving, not on alert and laying down or sitting down
with or without closing its eyes.
3. Feeding (F): When a subject eats, drinks, forages or any behavior associated with eating,
drinking or foraging.
4. Scanning (S): When a subject is on alert and is looking around. Subject can be standing,
sleeping or laying down.
5. Peaceful Interactions (PI): When a subject is in a peaceful or submissive interaction
with others. This category can also include a subject playing or playing with others.
6. Aggressive Interactions (AI): When a subject exhibits aggressive behavior toward
others.
7. Sexual Acts (SA): When a subject is engaging in sexual activity with another individual
or on themselves such as copulating, masturbating or presenting.
8. Grooming (G): When a subject is grooming or being groomed. This includes
allogrooming and autogrooming behaviors. This category does not receive a check;
instead, it is written as MF, MM, FM, FF or Self if observed at time interval. These letters
represent “male” (M) and “female” (F). The first letter represents the groomer and the
second letter represents the one being groomed. When a subject is the same sex as the
groomer and is being groomed, parentheses are used to indicate that the groomer is not
the subject. “Self” represents self grooming or autogrooming.
Ho 17
9. Out of Sight (OS): When a subject is behind the exhibit, not visible or obstructed by
terrain.
RESULTS
Figure 2, Table 6 and Table 7 shows the activity budget of hamadryas baboons and
geladas in this study. The percentage of time spent grooming in geladas was 13.5%, while in
hamadryas it was 41.4%. The difference was 27.9%. Even though these hamadryas (n = 10)
spent more time grooming than the geladas (n = 6), the difference was not statistically significant
(MW test: Z-value = 41, P-value = 0.313). This result did not support the hypothesis that there is
a higher frequency of grooming in hamadryas compared to geladas.
Figure 3 compares the percentage of total grooming time spent autogrooming and
allogrooming between geladas and hamadryas. In geladas, 12.7% of grooming time was spent on
autogrooming while the rest of their grooming time, 87.4%, was spent allogrooming. In
hamadryas, 9.5% was spent autogrooming while 90.5% was spent allogrooming. The frequency
of allogrooming was higher than autogrooming in both geladas and hamadryas. There was a
significant difference between percentage of time spent autogrooming and allogrooming in
hamadryas (n = 10) and geladas (n = 6), (MW test: Z-value = 184, P-value = 0.003). This result
supported the hypothesis that there is a higher frequency of allogrooming compared to
autogrooming in both geladas and hamadryas baboons.
When compared between sexes, male geladas groomed 3.1% of the total time while
females groomed 13.9% of the total time (Figure 4, Table 8 and Table 9). Even though female
geladas (n = 4) spent more time grooming compared to gelada males (n = 2), this difference was
not statistically significant (MW test: Z-value = 4, P-value = 0.267). This result did not support
the hypothesis that there is a higher frequency of grooming done by gelada females than by
gelada males.
Hamadryas males groomed on average, 36.1% of the total time while hamadryas females
groomed on average, 28.1% of the total time (Figure 5, Table 10 and Table 11). The hamadryas
males (n = 5) in this study spent more time grooming than the females (n = 5). However, this
difference was not statistically significant (MW test: Z-value = 30, P-value = 0.690). This result
did not support the hypothesis that there is a higher frequency of grooming done by hamadryas
males than by hamadryas females.
Figures 6 to 8, and Tables 12 to 18 show comparisons of types of grooming from
averages across all individuals based on total grooming time. On average, hamadryas females (n
= 5) in this study groomed each other less (12.5%) than gelada females (n = 4; 36.6%), but this
difference (24.1%) was not statistically significant (MW test: Z-value = 24.5, P-value = 0.306),
and so it did not support the hypothesis that gelada females groom each other more frequently
than hamadryas females.
Ho 18
On average, hamadryas males (n = 5) in this study groomed each other frequently
(45.5%) but gelada males (n = 2) did not (0.0%). There was no recorded grooming between
gelada males. Even though the hamadryas males groom each other more than gelada males, the
difference was not statistically significant (MW test: Z-value = 5, P-value = 0.285), and so it did
not support the hypothesis that hamadryas males groom each other more than gelada males.
Figure 9 and Table 19 show time spent grooming among females and between leader
males and females in the same gelada group. Based on focal time samples of gelada females,
they received an average of 48.5% of their leader male's (n = 4) total grooming time . Grooming
among female geladas (n = 4) was an average of 36.5% of their total grooming time. There was a
12.0% difference (MW test: Z-value = 21, P-value = 0.486). However, the result was not
statistically significant, and so it did not support the hypothesis that there is a higher frequency of
grooming among females compared to between leader males and females in the same gelada
group.
Figure 10 and Table 20 show time spent grooming among females and between leader
males and females in hamadryas. Based on focal time samples of hamadryas females, they
received an average of 31.4% of their leader male's (n = 5) total grooming time. Grooming
among female hamadryas (n = 5) was an average of 18.9% of their total grooming time. There
was a 12.5% difference (MW test: Z-value = 29, P-value = 0.830). However, the result was not
statistically significant, and so it did not support the hypothesis that there is a higher frequency of
grooming between leader males and females compared to among females in the same hamadryas
group.
Figure 11 and Table 21 show a comparison of time spent grooming between leader males
and their females in both hamadryas and geladas. Based on focal time samples of hamadryas
baboons and gelada leader males, hamadryas leader males groomed their females (n=5) an
average of 58.9% of their total grooming time while the gelada leader males groomed their
females (n=4) an average of 93.7% of their total grooming time. There was a 34.8% difference
(MW test: Z-value = 22.5, P-value = 0.623). This result did not support the hypothesis that there
is a higher frequency of grooming between leader males and his females in a hamadryas group
than a gelada group. A statistical test was conducted and showed that this result was not
statistically significant. Therefore, this result does not necessarily disprove the hypothesis.
Figures 12 through 21 show the frequency of grooming in hamadryas by dyad and
autogrooming by individual based on total grooming time. Ben spent 32.4% of his grooming
time on Neji and 27.1% of his grooming time on Mimi and Fifi. Fadi spent 70.8% of his
grooming time on Neji and 27% of his grooming time on Ken. Neji’s grooming time was spent
on Ben (21.7%), Fadi (11.3%) and Ken (49.1%). Neji, who clearly belongs to Ben's OMU,
would occasionally herd Pam out of Leo's OMU and groom her (14.1%). Ken spent 79.6% of his
grooming time on Fadi and 20.4% of his grooming time on Neji. Leo spent his grooming time on
Jenn (86.1%) and (5.2%) but none (0.0%) on Anne.
Mimi spent 19.2% of her grooming time on Fifi, 36.6% on Ben and 36.3% on Ken. Fifi
Ho 19
spent 43.3% of her grooming time on Mimi, 26.6% on Ben and 14.3% on Ken. Both Mimi and
Fifi groomed each other frequently, possibly because they are mother and daughter. Jenn spent
93.4% of her grooming time on Leo. Anne spent 33.3% of her grooming time on Jenn but none
(0.0%) on Pam and Leo. Pam spent all her grooming time (100.0%) on herself and was never
recorded grooming Neji (0.0%). Jenn and Pam were never observed grooming any of the females
in their OMU. Anne only groomed Jenn and not Pam. Jenn is the highest ranking female in her
OMU, followed by Anne. Pam is the lowest ranking female in her OMU. None of these females
are related.
Figures 22 through 27 show the frequency of grooming in geladas by dyad and
autogrooming by individual based on total grooming time. Patrick spent 69.7% of his grooming
time on Lynne, 21.1% on Marie and 0.0% on Syndee. Bruce on the other hand, spent 96.6% of
his grooming time on Bonnie.
Lynne spent none of her grooming time (0.0%) on Marie, 75.7% on Patrick and 8.6% on
Syndee. Marie spent 70.4% of her grooming time on Syndee, 19.0% on Patrick and none (0.0%)
on Lynne. Syndee spent 1.0% of her grooming time on Lynne, 1.0% on Patrick and 66.0% on
Marie. Because spent 96.1% of her grooming time on Bruce.
Figure 29 shows the correlation between temperature and average grooming frequency in
hamadryas baboons. I conducted a SRCC Test (n = 8) and found that the rs value = 0.7619 and
that the P-value = 0.037. This result shows that there is a statistically significant relationship
between temperature and average grooming frequency in hamadryas baboons. This supports the
hypothesis that as temperature increases, grooming frequency also increases in hamadryas
baboons.
Figure 30 shows the correlation between temperature and average grooming frequency in
geladas. I conducted a SRCC Test (n = 8) and found that the rs value = -0.119 and that the P-
value = 0.793. The result was not statistically significant and did not support my hypothesis that
geladas spend more time grooming as temperature increases.
DISCUSSION
Both the hamadryas and the geladas in the study had a higher frequency of allogrooming
than autogrooming. The difference was statistically significant, and therefore supported my
hypothesis that in hamadryas baboons and geladas, a higher frequency of allogrooming is
expected compared to autogrooming. These data supported the idea that social primates tend to
engage in allogrooming more than autogrooming. Further observation could be done to see if
there is a similar relationship between allogrooming and autogrooming in social versus solitary
primates.
There was a higher frequency of grooming done by hamadryas males than by hamadryas
females in this study. However, the result was not statistically significant, and so it does not
support my hypothesis that there is a higher frequency of grooming done by hamadryas males
Ho 20
than by hamadryas females. There was a high frequency of grooming between two females,
Mimi and Fifi. This was possibly due to the fact that they are mother and daughter. Kummer
(1968) found that the lack of female grooming was due to the leader male, who does not allow
females from the same OMU to groom each other. Ben, the leader male of Mimi and Fifi's OMU,
did not seem to mind that Mimi and Fifi groomed each other frequently. Ben's high tolerance
might have been because he is also Fifi's father. Jenn was observed grooming Leo constantly.
There was a higher frequency of grooming done by gelada females than by gelada males
in this study but it was not statistically significant so it does not support my hypothesis that there
is a higher frequency of grooming done by gelada females than by gelada males. Due to a small
sample size for gelada males, the result was not statistically significant, and so we cannot
conclude that gelada females groom more. Future observations should be done on groups with a
larger sample size to confirm or contradict this hypothesis. This is also possibly due to the data
from two female outliers, Syndee and Bonnie. Lynne spent 20.34% of her time grooming, Marie
spent 23.66% of her time grooming, Syndee spent 11.50% of her time grooming and Bonnie
spent 0.23% of her time grooming.
Based on focal time samples of hamadryas females, they received slightly more grooming
from their leader males than from each other. However, the result was not statistically significant,
and so it does not support the hypothesis that there is a higher frequency of grooming between
leader males and females compared to among females in the same hamadryas OMU. Mimi and
Fifi were observed grooming each other more than female hamadryas baboons were expected to
while Leo was observed grooming Jenn almost exclusively.
Based on focal time samples of gelada females, they received slightly more grooming
from each other than from their leader males. However, this result was not statistically
significant, and so it did not support the hypothesis that there is a higher frequency of grooming
among females compared to between leader males and females in the same gelada group.
Females were never observed grooming outside of their OMU; none of Patrick's females
groomed Bonnie. Bonnie was groomed by Bruce exclusively because she is the only female in
the OMU. Females in the same OMU often form grooming dyads and spend a majority of the
time grooming their partner.
There was a higher frequency of grooming among hamadryas males in this study than
among gelada males. Even though the hamadryas males groomed each other more than gelada
males, the difference was not statistically significant. This result did not support the hypothesis
that hamadryas males groom each other more than gelada males. There was no recorded
grooming between gelada males, probably due to the fact that there were only 2 male geladas in
the enclosure and both of them are unrelated leader males. All hamadryas males in this study,
however, were related except for Leo. Future observation should be done on gelada groups with
related males to confirm or contradict this hypothesis.
There was a higher frequency of grooming among gelada females than among hamadryas
females, but this difference was not statistically significant, and so it did not support the
Ho 21
hypothesis that gelada females groom each other more frequently than hamadryas females.
Gelada females from Patrick's OMU were observed grooming each other while Bonnie, the only
gelada female from Bruce's OMU, was never observed grooming another female outside of her
OMU. There was also a high frequency of grooming between Mimi and Fifi, probably because
they are related to each other as mother and daughter. Future observation should be done on
gelada groups with multiple females in a OMU to confirm or contradict this hypothesis.
Based on focal time samples of both hamadryas and gelada leader males, there was a
higher frequency of grooming between gelada leader males and their females than between
hamadryas leader males and their females. This does not support the hypothesis that there is a
higher frequency of grooming between leader males and their females in the hamadryas group
than the gelada group. Gelada leader males were observed grooming their females more than
hamadryas leader males were observed grooming their females. In Ben's OMU, all the other
males are his offspring. Because these males are related, Ben spent some of his time grooming
these males instead of only grooming his females.
In this study, hamadryas baboons spent more time grooming compared to geladas based
on their activity budget. However, this difference was not statistically significant, and so it does
not support the hypothesis that there is a higher frequency of grooming in hamadryas compared
to geladas. Individuals from both hamadryas and gelada groups spent about the same amount of
time grooming themselves and each other with the exception of Mimi, Leo and Jenn. Mimi spent
most of her time grooming her leader male and her offspring while Leo and Jenn spent a large
amount of their time grooming each other. Leo was never observed fighting Neji to get Pam back
as Neji herded her away from Leo's OMU. Instead, Leo obsessively groomed Jenn, his favorite
female, to make sure that she did not leave his sight and get herded away. The reason why Leo
and Jenn groomed each other obsessively may have been to cope with stress and overcrowding.
Mimi, on the other hand, spent most of her time grooming her leader male and offspring. It did
not seem that Mimi was grooming others to gain favor, as she was probably highest in the
dominance hierarchy after her leader male. Instead, she might have been grooming to cope with
stress and overcrowding.
In this study, there was a positive correlation between the time spent grooming in
hamadryas baboons and temperature. The higher the temperature was, the higher the frequency
of grooming was. The correlation was statistically significant, supporting the hypothesis that
hamadryas baboons spend more time grooming as temperature increases. As the temperature
decreased, these hamadryas baboons spent most of their time sleeping or foraging. However, as
the temperature increased, they spent most of their time grooming themselves and each other.
This is probably because it is much more comfortable for the hamadryas baboons to groom each
when the temperature increases. When it is cold, these hamadryas baboons tend to sleep most of
time or sit inside heated enclaves.
In this study, there was a negative correlation between time spent grooming in geladas
and temperature. The lower the temperature was, the higher the frequency of grooming was. The
correlation was not statistically significant, nor did the result support the hypothesis that geladas
Ho 22
spend more time grooming as temperature increases. As the temperature increased, these geladas
were observed foraging most of the time. The frequency of grooming increased when the
temperature decreased, probably in response to the geladas being in close proximity to their
grooming partner while huddling inside heated enclaves or on heated rocks.
Ben was observed grooming Neji, a sub-adult male in his OMU (Figure 12). This was not
at all surprising because Neji is Ben's offspring. However, based on Ben's focal samples, it
seemed that he spent a majority of his time autogrooming. This may have been a tension-
reduction mechanism. Based on his focal samples, Fadi spent his grooming time on himself, Neji
and Ken (Figure 13). Both Neji and Ken are younger than Fadi and are both his brothers. Fadi
spent most of his time grooming Neji and Ken, possibly to form alliances with the younger males
in the same group. Interestingly enough, Ben and Fadi, both fully adult males, were never
recorded grooming each other from their focal samples even though they are father and son. Neji
was frequently observed grooming Pam and herding her away from Leo's OMU (Figure 14).
There is a possibility that a third OMU will be started, with Neji as the leader male and Pam as
his female. Even though Neji was constrained in an enclosure, his natural instinct to start a OMU
was evident. Pam did not seem to mind being herded away from Leo because she was being
groomed by Neji. Leo was never observed grooming Pam. Based on Neji's focal samples, he also
groomed all the males in his group. This was probably because he wanted to form alliances with
them and also to gain agonistic support should Leo defend Pam against Neji. Based on his focal
samples, Ken spent his grooming time only on Fadi and Neji (Figure 15). Leo spent most of his
grooming time on Jenn (Figure 16). He was never observed grooming Anne and rarely groomed
Pam.
Mimi was observed grooming her offspring, Ken and Fifi, and her leader male, Ben
(Figure 17). Mimi spent about the same amount of time grooming Ben and Ken based on her
focal samples. She probably groomed her youngest offspring, Ken, more than expected as a form
of reassurance. Fifi also spent her grooming time on Mimi and Ken, aside from grooming her
leader male and herself (Figure 18). In this study, it was rare for females from the same OMU to
groom each other but Mimi and Fifi groomed each other most likely because they are mother and
daughter. In the wild, female hamadryas disperse from their natal groups but Fifi did not because
she was kept in an enclosure along with her family. Fifi probably spent her time grooming Ken
as a form of reassurance. Jenn exclusively groomed Leo and herself based on her focal samples
(Figure 19). Anne was observed grooming Jenn based on Anne's focal samples (Figure 20). I
interpret Anne's grooming behavior as a way of gaining favor from the highest-ranking female of
her OMU, Jenn. Based on her focal samples, Pam was only observed grooming herself and not
her leader male (Figure 21). She spent most of her time by herself, peripheral to her OMU.
Figure 22 shows that besides grooming himself, Patrick spent the rest of his grooming
time on Lynne and Marie. He was never observed grooming Syndee. The leader male was
peripheral in his OMU and spent most of his time grooming the alpha female, Lynne. Sometimes
the leader male groomed his other females when they were in estrus. Bruce spent most of his
grooming time on Bonnie because she was the only female in the OMU (Figure 23). Based on
the focal samples, Lynne spent most of her grooming time on Patrick and was also observed
Ho 23
grooming Syndee (Figure 24). In the wild, gelada females stay in their natal group and form
grooming dyads. Lynne probably groomed Syndee because they are related. Lynne is probably
not related to Marie. Aside from grooming her leader male, Marie was also observed grooming
Syndee (Figure 25). Gelada females from the same OMU tend to form grooming dyads, like
Marie and Syndee did. They spend the majority of their grooming time on their partner when not
grooming the leader male. Syndee was observed grooming both females in her OMU, Lynne and
Marie (Figure 26). Because Bonnie is the only female in her OMU, she spent her grooming time
between herself and her leader male, Bruce (Figure 27).
The results from this study are as follows:
1. There was a higher frequency of allogrooming compared to autogrooming in hamadryas
and geladas. The difference was statistically significant.
2. There was a higher frequency of grooming by hamadryas females than by hamadryas
males. However, the difference was not statistically significant, and so it did not support
the hypothesis.
3. There was a higher frequency of grooming by gelada females than by gelada males.
However, the difference was not statistically significant, and so it did not support the
hypothesis.
4. There was a higher frequency of grooming between females and their leader male than
among females in the same hamadryas group. However, the difference was not
statistically significant, and so it did not support the hypothesis.
5. There was a higher frequency of grooming among females than between females and
their leader male in the same gelada group. However, the difference was not statistically
significant, and so it did not support the hypothesis.
6. There was a higher frequency of grooming among hamadryas males than among gelada
males. However, the difference was not statistically significant, and so it did not support
the hypothesis.
7. There was a higher frequency of grooming among gelada females than hamadryas
females. However, the difference was not statistically significant, and so it did not
support the hypothesis.
8. There was a higher frequency of grooming between the leader male and his females in
gelada groups than hamadryas groups. The result did not support the hypothesis that there
would be a higher frequency of grooming between the leader male and his females in
hamadryas groups than gelada groups.
9. There was a higher frequency of grooming in hamadryas compared to geladas. However,
Ho 24
the difference was not statistically significant, and so it did not support the hypothesis.
10. Hamadryas baboons spent more time grooming as temperature increased. The correlation
was statistically significant.
11. Geladas spent more time grooming as temperature decreased. The correlation was not
statistically significant.
Some grooming behaviors are unique to hamadryas and geladas in captivity due to human
interference such as an abundance of food, safe shelter and limited dispersal range. We can
observe grooming patterns in captivity, but we cannot predict these patterns based on hamadryas
and geladas in the wild. Because these grooming behaviors persist in captivity, it reflects the
importance of these behaviors to the individuals.
My study supports the concept that grooming is important in social primates because it
helps to strengthen their social bonds. Even in captivity, both hamadryas and geladas groom each
other more than they groom themselves.
Ho 25
Table 1: Name, sex and age of hamadryas individuals from group H1 and H2 at The Prospect
Park Zoo.
Table 2: Correspondence between names given by The Prospect Park Zoo to their hamadryas
baboons (A) and names given by me during my observations at The Prospect Park Zoo (B).
A B
Simen Ben
Matara Mimi
Moja Fadi
Nyali Neji
Binti Fifi
Kito Ken
Bole Leo
Zula Jenn
Mekele Anne
Kobo Pam
Name Sex Age
Group H1
Ben Male Adult
Mimi Female Adult
Fadi Male Adult
Neji Male Sub-adult
Fifi Female Sub-adult
Ken Male Juvenile
Group H2
Leo Male Adult
Jenn Female Adult
Anne Female Adult
Pam Female Adult
Ho 26
Table 3: Name, sex and age of gelada individuals from group G1 and G2 at The Bronx Zoo.
Name Sex Age
Group G1
Patrick Male Adult
Lynne Female Adult
Marie Female Adult
Syndee Female Adult
Group G2
Bruce Male Adult
Bonnie Female Adult
Ho 27
Table 4: Possible grooming interactions between the hamadryas baboons at The Prospect Park
Zoo. (X) indicates self grooming or autogrooming. The first column represents the groomer
while the first row represents individuals being groomed.
Table 5: Possible grooming interactions between the geladas at The Bronx Zoo. (X) indicates
self grooming or autogrooming. The first column represents the groomer while the first row
represents individuals being groomed.
Focal Animal Ben Mimi Fadi Neji Fifi Ken Leo Jenn Anne Pam
Ben x
Mimi x
Fadi x
Neji x
Fifi x
Ken x
Leo x
Jenn x
Anne x
Pam x
Focal Animal Patrick Lynne Marie Syndee Bruce Bonnie
Patrick x
Lynne x
Marie x
Syndee x
Bruce x
Bonnie x
Table 6: Comparison of activity budget between the geladas and hamadryas baboons. Numbers are raw counts of point time samples
across individuals.
Table 7: Comparison of activity budget between the geladas and hamadryas baboons. Numbers are percentage of total point time
samples across individuals.
Species
Geladas 8.5 10.2 55.7 11.0 0.6 0.1 0.0 13.5 0.5 100.1
Hamadryas Baboons 9.2 12.0 6.4 29.0 1.1 1.1 0.2 40.8 0.3 100.1
Locomoting
(%) Resting
(%) Feeding
(%) Scanning
(%)
Peaceful
Interactions
(%)
Aggressive
Interactions
(%)
Sexual
Acts
(%) Grooming
(%)
Out of
Sight
(%) Total
(%)
Species Locomoting Resting Feeding Scanning Grooming Total
Geladas 395 473 2588 511 29 3 0 629 22 4650
Hamadryas Baboons 429 556 296 1349 53 50 81897 12 4650
Peaceful
Interactions Aggressive
Interactions Sexual
Acts Out of
Sight
Ho 29
Table 8: Grooming frequency of geladas at The Bronx Zoo, by sex.
Table 9: Mean grooming frequency of geladas at The Bronx Zoo, by sex.
Name Sex
Patrick Male 86 1116 0.06
Bruce Male 61 992 6.15
Lynne Female 145 713 20.34
Marie Female 154 651 23.66
Syndee Female 82 713 11.50
Bonnie Female 101 465 0.23
Grooming
Points (n) Total Point Time
Samples (N) Grooming Frequency (n/N),
(%)
Sex Mean Grooming Frequency (%)
Male 3.1
Female 13.9
Ho 30
Table 10: Grooming frequency of hamadryas baboons at The Prospect Park Zoo, by sex.
Table 11: Mean grooming frequency of hamadryas baboons at The Prospect Park Zoo, by sex.
Name Sex
Ben Male 199 682 29.18
Fadi Male 141 372 37.90
Neji Male 197 279 70.61
Ken Male 0 62 0.00
Leo Male 333 775 42.97
Mimi Female 655 961 68.16
Fifi Female 100 310 32.26
Jenn Female 291 806 36.10
Anne Female 3 217 1.38
Pam Female 5 186 2.69
Grooming
Points (n) Total Point Time
Samples (N) Grooming Frequency (n/N),
(%)
Sex Mean Grooming Frequency (%)
Male 36.1
Female 28.1
Ho 31
Table 12: Percent time spent grooming among geladas (The Bronx Zoo). Numbers are from raw counts of total grooming time in
autogrooming and allogrooming across all individuals.
Geladas
(Name)
Autogrooming
Male
grooming
another male
Male
grooming
another
female
Female
grooming
another male
Female
grooming
another female
Male being
groomed by a
female
Female being
groomed by a male
Total
Grooming
Patrick
7
0
36
0
0
43
0
86
Bruce
2
0
18
0
0
41
0
61
Lynne
22
0
0
81
7
0
35
145
Marie
15
0
0
8
126
0
5
154
Syndee
32
0
0
1
49
0
0
82
Bonnie
2
0
0
61
0
0
38
101
Total
80
0
54
151
182
84
78
629
Total (%)
12.7
0.0
11.3
17.6
28.9
19.7
9.7
99.9
Geladas
(Name)
Autogrooming
(%)
Male
grooming
another male
(%)
Male
grooming
another
female (%)
Female
grooming
another male
(%)
Female
grooming
another female
(%)
Male being
groomed by a
female (%)
Female being
groomed by a male
(%)
Total
Grooming (%)
Patrick
8.1
0.0
41.9
0.0
0.0
50.0
0.0
100.0
Bruce
3.3
0.0
29.5
0.0
0.0
67.2
0.0
100.0
Lynne
15.2
0.0
0.0
55.9
4.8
0.0
24.1
100.0
Marie
9.7
0.0
0.0
5.2
81.8
0.0
3.2
99.9
Syndee
39.0
0.0
0.0
1.2
59.8
0.0
0.0
100.0
Bonnie
2.0
0.0
0.0
60.4
0.0
0.0
37.6
100.0
Ho 32
Table 13: Percent time spent grooming among hamadryas baboons (The Prospect Park
Zoo). Numbers are from raw counts of total grooming time in autogrooming and
allogrooming across all individuals. Ken was never observed grooming in any of his
samples; therefore he has 0 grooming points in all categories.
Hamadryas
(Name)
Autogrooming
Male
grooming
another
male
Male
grooming
another
female
Female
grooming
another
male
Female
grooming
another
female
Male
being
groomed
by a
female
Female
being
groomed
by a male
Total
Grooming
Ben
30
16
6
0
0
147
0
199
Fadi
3
138
0
0
0
0
0
141
Neji
4
149
18
0
0
26
0
197
Ken
0
0
0
0
0
0
0
0
Leo
33
0
208
0
0
92
0
333
Mimi
57
0
0
406
192
0
0
655
Fifi
32
0
0
55
0
0
13
100
Jenn
16
0
0
134
0
0
141
291
Anne
2
0
0
0
1
0
0
3
Pam
5
0
0
0
0
0
0
5
Total
182
303
232
595
193
265
154
1924
Total (%)
9.5
15.7
12.1
31.0
10.0
13.8
8.0
100.1
Hamadryas
(Name)
Autogrooming
(%)
Male
grooming
another
male
(%)
Male
grooming
another
female
(%)
Female
grooming
another
male
(%)
Female
grooming
another
female
(%)
Male
being
groomed
by a
female
(%)
Female
being
groomed
by a male
(%)
Total
Grooming
(%)
Ben
15.1
8.0
3.0
0.0
0.0
73.9
0.0
100.0
Fadi
2.1
97.9
0.0
0.0
0.0
0.0
0.0
100.0
Neji
2.0
75.6
9.1
0.0
0.0
13.2
0.0
99.9
Ken
0.0
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Leo
9.9
0.0
62.5
0.0
0.0
27.6
0.0
100.0
Mimi
8.7
0.0
0.0
62.0
29.3
0.0
0.0
100.0
Fifi
32.0
0.0
0.0
55.0
0.0
0.0
13.0
100.0
Jenn
5.5
0.0
0.0
46.0
0.0
0.0
48.5
100.0
Anne
66.7
0.0
0.0
0.0
33.3
0.0
0.0
100.0
Pam
100.0
0.0
0.0
0.0
0.0
0.0
0.0
100.0
Table 14: Comparison of percent time spent grooming between geladas (The Bronx Zoo) and hamadryas baboons (The Prospect Park
Zoo) by sex. Numbers are average percentage of total grooming time in autogrooming and allogrooming across all individuals.
Sex
Average
autogrooming
(%)
Average
male
grooming
another male
(%)
Average
male
grooming
another
female (%)
Average
female
grooming
another male
(%)
Average
female
grooming
another
female (%)
Average
male being
groomed by
a female
(%)
Average
female being
groomed by a
male
(%)
Total
Grooming
(%)
Male geladas
5.7
0.0
35.7
0.0
0.0
58.6
0.0
100.0
Female geladas
16.5
0.0
0.0
30.7
36.6
0.0
16.2
100.0
Sex
Average
autogrooming
(%)
Average
male
grooming
another male
(%)
Average
male
grooming
another
female (%)
Average
female
grooming
another male
(%)
Average
female
grooming
another
female (%)
Average
male being
groomed by
a female
(%)
Average
female being
groomed by a
male
(%)
Total
Grooming
(%)
Male hamadryas
7.3
45.4
18.7
0.0
0.0
28.7
0.0
100.1
Female hamadryas
42.6
0.0
0.0
32.6
12.5
0.0
12.3
100.0
Table 15: Time spent grooming by dyad and autogrooming in hamadryas baboons. The first column represents the groomer while the
first row represents individuals being groomed. Numbers are raw counts of grooming time across all individuals.
Table 16: Time spent grooming by dyad and autogrooming in hamadryas baboons. The first column represents the groomer while the
first row represents individuals being groomed. Numbers are percentage of total grooming time across all individuals.
Name Ben Fadi Neji Ken Leo Mimi Fifi Jenn Anne Pam
Ben 40.5 0.0 32.4 0.0 0.0 1.4 25.7 0.0 0.0 0.0 100.0
Fadi 0.0 2.2 70.8 27.0 0.0 0.0 0.0 0.0 0.0 0.0 100.0
Neji 21.7 11.3 3.8 49.1 0.0 0.0 0.0 0.0 0.0 14.1 100.0
Ken 0.0 79.6 20.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 100.0
Leo 0.0 0.0 0.0 0.0 8.7 0.0 0.0 86.1 0.0 5.2 100.0
Mimi 36.6 0.0 0.0 36.3 0.0 8.0 19.2 0.0 0.0 0.0 100.1
Fifi 26.6 0.0 0.0 14.3 0.0 43.3 15.8 0.0 0.0 0.0 100.0
Jenn 0.0 0.0 0.0 0.0 93.4 0.0 0.0 6.6 0.0 0.0 100.0
Anne 0.0 0.0 0.0 0.0 0.0 0.0 0.0 33.3 66.7 0.0 100.0
Total (%)
Name Ben Fadi Neji Ken Leo Mimi Fifi Jenn Anne Pam Total
Ben 30 024 0 0 1 19 0 0 0 74
Fadi 0 3 97 37 0 0 0 0 0 0 137
Neji 23 12 452 0 0 0 0 0 15 106
Ken 043 11 0 0 0 0 0 0 0 54
Leo 0 0 0 0 33 0 0 328 020 381
Mimi 261 0 0 259 057 137 0 0 0 714
Fifi 54 0 0 29 088 32 0 0 0 203
Jenn 0 0 0 0 226 0 0 16 0 0 242
Anne 0 0 0 0 0 0 0 1 2 0 3
Table 17: Time spent grooming by dyad and autogrooming in geladas. The first column represents the groomer while the first row
represents individuals being groomed. Numbers are raw counts of grooming time across all individuals.
Table 18: Time spent grooming by dyad and autogrooming in geladas. The first column represents the groomer while the first row
represents individuals being groomed. Numbers are percentage of total grooming time across all individuals.
Name Patrick Bruce Lynne Marie Syndee Bonnie Total
Patrick 7 0 53 16 0 0 76
Bruce 0200056 58
Lynne 106 022 012 0140
Marie 27 0 0 15 100 0142
Syndee 10166 32 0100
Name Patrick Bruce Lynne Marie Syndee Bonnie Total (%)
Patrick 9.2 0.0 69.7 21.1 0.0 0.0 100.0
Bruce 0.0 3.4 0.0 0.0 0.0 96.6 100.0
Lynne 75.7 0.0 15.7 0.0 8.6 0.0 100.0
Marie 19.0 0.0 0.0 10.6 70.4 0.0 100.0
Syndee 1.0 0.0 1.0 66.0 32.0 0.0 100.0
Table 19: Time spent grooming by leader male to female (MF) and by other females (FF) in geladas based on focal female samples.
Numbers are raw count of grooming time and percentage of grooming time across all female individuals.
Geladas Females MF %FF %
Lynne 106 75.7 12 8.6 140
Marie 27 19.0 100 70.4 142
Syndee 1 1.0 67 67.0 100
Bonnie 102 98.1 0 0.0 104
TOTAL 236 193.8 179 146.0
Average Grooming 59 48.5 45 36.5
Total Point
Grooming
Table 20: Time spent grooming by leader male to female (MF) and by other females (FF) in hamadryas baboons based on focal
female samples. Numbers are raw count of grooming time and percentage of grooming time across all female individuals.
Hamadryas Females MF %FF %
Mimi 258 37.0 124 17.8 697
Fifi 54 26.6 88 43.3 203
Jenn 226 93.4 0 0.0 242
Anne 0 0.0 1 33.3 3
Pam 0 0.0 0 0.0 5
TOTAL 538 157.0 213 94.4
Average Grooming 108 31.4 43 18.9
Total Point
Grooming
Table 21: Time spent grooming by leader male to female (MF) in hamadryas baboons and geladas based on focal female samples.
Numbers are raw count of grooming time and percentage of grooming time across all leader male individuals.
Gelada Males MF %
Patrick 69 90.8 76
Bruce 56 96.6 58
TOTAL 125 187.4
Average Grooming 63 93.7
Total Point
Grooming
Hamadryas Males MF %
Ben 20 31.7 63
Leo 328 86.1 381
TOTAL 348 117.8
Average Grooming 174 58.9
Total Point
Grooming
Ho 39
Location: BZ/PPZ Focal Species: G / H Sex: M / F Date: __________________
Weather: ___________________ Temperature: ________ ºF Time Started: _________________
Time Δ (min)
L
R
F
S
P I
AI
SA
G
(MF, MM, FM, FF or
self)
OS
0:00
0:20
0:40
1:00
1:20
1:40
2:00
2:20
2:40
3:00
3:20
3:40
4:00
4:20
4:40
5:00
5:20
5:40
6:00
6:20
6:40
7:00
7:20
7:40
8:00
8:20
8:40
9:00
9:20
9:40
10:00
TOTAL
Time Ended: _______________ Name _________________
Comments:
___________________________________________________________________________________________
Figure 1: Focal Time Sampling Check Sheet
Figure 2: Comparison of activity budget between geladas and hamadryas baboons.
Locomoting
Resting
Feeding
Scanning
Peaceful Interactions
Aggressive Interactions
Sexual Acts
Grooming
Out of Sight
0.0
10.0
20.0
30.0
40.0
50.0
60.0
8.5 10.2
55.7
11.0
0.6 0.1
13.5
0.5
8.7 12.0
6.4
29.2
1.1 1.1 0.2
41.0
0.3
Comparison of Activity Budget Between Geladas and Hamadryas
Geladas
Hamadryas Baboons
Behavioral Categories
Percentage of total time (%)
Ho 41
Figure 3: Comparison of percentage of total grooming time spent autogrooming and
allogrooming in gelada and hamadryas baboons.
Gelada Baboons Hamadryas Baboons
0
10
20
30
40
50
60
70
80
90
100
13% 10%
87% 91%
Percentage of Total Grooming Time Spent Autogrooming and Allogrooming
in Geladas and Hamadryas Baboons
Autogrooming
Allogrooming
Species
Percentage of total grooming time (%)
Ho 42
Figure 4: Comparison of percentage of total time spent grooming by males and females in
geladas based on male focal samples and female focal samples.
Males Females
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
3.1
13.9
Percentage of Total Time Spent Grooming by
Males vs. Females: Geladas
Sex
Percentage of total time (%)
Ho 43
Figure 5: Comparison of percentage of total time spent grooming by males and females in
hamadryas based on male focal samples and female focal samples.
Males Females
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
36.1
28.1
Percentage of Total Time Spent Grooming by
Males vs. Females: Hamadryas
Sex
Percentage of total time (%)
Figure 6: Time spent grooming, by sex in geladas at The Bronx Zoo. Percentage represents averages across all individuals, based on
total grooming time
Male geladas Female geladas
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Percentage of Total Grooming Time Spent on Types on Grooming: Geladas
Average female being
groomed by a male
Average male being groomed
by a female
Average female grooming
another female
Average female grooming
another male
Average male grooming
another female
Average male grooming
another male
Average autogrooming
Percentage of total grooming time spent on each type of grooming
Figure 7: Time spent grooming, by sex in hamadryas baboons at The Prospect Park Zoo. Percentage represents averages across all
individuals, based on total grooming time.
Male hamadryas Female hamadryas
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Percentage of Total Grooming Time Spent on Types of Grooming: Hamadryas Baboons
Average female being
groomed by a male
Average male being
groomed by a female
Average female grooming
another female
Average female grooming
another male
Average male grooming
another female
Average male grooming
another male
Average autogrooming
Percentage of total grooming time spent on each type of grooming
Figure 8: Comparison of percentage of total grooming time (based on averages across all individuals) spent in each type of grooming
by each sex of each species.
Male geladas Male hamadryas Female geladas Female hamadryas
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Percentage of Total Grooming Time Spent on Types of Grooming:
Geladas and Hamadryas Baboons
Average female being
groomed by a male
Average male being
groomed by a female
Average female grooming
another female
Average female grooming
another male
Average male grooming
another female
Average male grooming
another male
Average autogrooming
Percentage of total grooming time spent on each type of grooming
Ho 47
Figure 9: Comparison of percentage of total grooming time spent being groomed by leader male
(MF) and percentage of grooming time spent groomed by other females (FF) in geladas. These
numbers represent the average percent of total grooming time across female focal samples.
MF FF
0.0
10.0
20.0
30.0
40.0
50.0
60.0
48.5
36.5
Time Spent Grooming Between Leader Male and Females, and Among Females,
as a Percentage of Total Grooming Time in Geladas
Types of grooming
Percentage of total grooming time (%)
Ho 48
Figure 10: Comparison of percentage of total grooming time spent being groomed by a male
(MF) and percentage of grooming time spent being groomed by other females (FF) in hamadryas
baboons. These numbers represent the average percent of total grooming time across female
focal samples.
MF FF
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
31.4
18.9
Time Spent Grooming Between Leader Male and Females, and Among Females,
as a Percentage of Total Grooming Time in Hamadryas Baboons
Types of grooming
Percentage of total grooming time (%)
Ho 49
Figure 11: Comparison of percentage of total grooming time spent by leader male grooming
females (MF), in geladas and hamadryas baboons. These numbers represent the average percent
of total grooming time across leader male focal samples.
Geladas (MF) Hamadryas (MF)
0
10
20
30
40
50
60
70
80
90
100 93.7
58.9
Time Spent Grooming Between Leader Male and Females as a Percentage of
Total Grooming Time in Geladas and Hamadryas Baboons
Average percentage of grooming time (%)
Ho 50
Figure 12: Ben's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Ben's focal samples.
SELF Fadi Neji Ken Leo Mimi Fifi Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
40.5
32.4
1.4
25.7
Ben's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Ben
Individuals
Percentage of total grooming time (%)
Ho 51
Figure 13: Fadi's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Fadi's focal samples.
Ben SELF Neji Ken Leo Mimi Fifi Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
2.2
70.8
27.0
Fadi's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Fadi
Individuals
Percentage of total grooming time (%)
Ho 52
Figure 14: Neji's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Neji's focal samples.
Ben Fadi SELF Ken Leo Mimi Fifi Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
21.7
11.3
3.8
49.1
14.1
Neji's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Neji
Individuals
Percentage of total grooming time (%)
Ho 53
Figure 15: Ken's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Ken's focal samples.
Ben Fadi Neji SELF Leo Mimi Fifi Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
79.6
20.4
Ken's Percent Time Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Ken
Individuals
Percentage of total grooming time (%)
Ho 54
Figure 16: Leo's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Leo's focal samples.
Ben Fadi Neji Ken SELF Mimi Fifi Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
8.7
86.1
5.2
Leo's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Leo
Individuals
Percentage of total grooming time (%)
Ho 55
Figure 17: Mimi's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Mimi's focal samples.
Ben Fadi Neji Ken Leo SELF Fifi Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
36.6 36.3
8.0
19.2
Mimi's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Mimi
Individuals
Percentage of total grooming time (%)
Ho 56
Figure 18: Fifi's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Fifi's focal samples.
Ben Fadi Neji Ken Leo Mimi SELF Jenn Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
26.6
14.3
43.3
15.8
Fifi's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Fifi
Individuals
Percentage of total grooming time (%)
Ho 57
Figure 19: Jenn's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Jenn's focal samples.
Ben Fadi Neji Ken Leo Mimi Fifi SELF Anne Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
93.4
6.6
Jenn's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Jenn
Individuals
Percentage of total grooming time (%)
Ho 58
Figure 20: Anne's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Anne's focal samples.
Ben Fadi Neji Ken Leo Mimi Fifi Jenn SELF Pam
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
33.3
66.7
Anne's Time Spent Grooming By Dyad and Autogrooming
Based on Total Grooming Time
Anne
Individuals
Percentage of total grooming time (%)
Ho 59
Figure 21: Pam's time spent grooming by dyad and autogrooming based on total grooming time.
Numbers based on Pam's focal samples.
Ben Fadi Neji Ken Leo Mimi Fifi Jenn Anne SELF
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0 100.0
Pam's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Pam
Individuals
Percentage of total grooming time(%)
Ho 60
Figure 22: Patrick's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Patrick's focal samples.
SELF Bruce Lynne Marie Syndee Bonnie
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
9.2
69.7
21.1
Patrick's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Patrick
Individuals
Percentage of total grooming time (%)
Ho 61
Figure 23: Bruce's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Bruce's focal samples.
Patrick SELF Lynne Marie Syndee Bonnie
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
3.4
96.6
Bruce's Percent Time Grooming by Dyad and Autogrooming
Bruce
Individuals
Percentage of total grooming time (%)
Ho 62
Figure 24: Lynne's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Lynne's focal samples.
Patrick Bruce SELF Marie Syndee Bonnie
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
75.7
15.7
8.6
Lynne's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Lynne
Individuals
Percentage of total grooming time (%)
Ho 63
Figure 25: Marie's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Marie's focal samples.
Patrick Bruce Lynne SELF Syndee Bonnie
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
19.0
10.6
70.4
Marie's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Marie
Individuals
Percentage of total grooming time (%)
Ho 64
Figure 26: Syndee's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Syndee's focal samples.
Patrick Bruce Lynne Marie SELF Bonnie
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
1.0 1.0
66.0
32.0
Syndee's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Syndee
Individuals
Percentage of total grooming time (%)
Ho 65
Figure 27: Bonnie's time spent grooming by dyad and autogrooming based on total grooming
time. Numbers based on Bonnie's focal samples.
Patrick Bruce Lynne Marie Syndee SELF
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0 98.1
1.9
Bonnie's Time Spent Grooming by Dyad and Autogrooming
Based on Total Grooming Time
Bonnie
Individuals
Percentage of total grooming time (%)
Ho 66
Figure 28: Relationship between average grooming events per 10 minutes and
temperature (°F) in hamadryas baboons.
30 35 40 45 50 55 60 65 70
0
5
10
15
20
25
30
Relationship between Average Grooming Frequency and Temperature (°F)
in Hamadryas Baboons
Temperature (°F)
Average Grooming Events per 10 Minutes
Ho 67
Figure 29: Relationship between average grooming events per 10 minutes and
temperature (°F) in geladas.
30 35 40 45 50 55 60 65
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
Relationship between Average Grooming Frequency and Temperature (°F)
in Geladas
Temperature (°F)
Average Grooming Events per 10 Minutes
Ho 68
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