Baboons are among the most flexible, adaptable, and opportunistic animals on earth. As described below, they occupy an exceptional array of habitats and are highly variable in their feeding habits. Although they are affected by ecological variables in similar ways as other animals, baboons are more adaptable than most and as a result have colonised a wide variety of niches across Africa. As one consequence of their ecological flexibility, they do quite well when living alongside humans.
Habitat. Baboons are found in almost every habitat across Africa. Olive, yellow, and chacma baboons are often called ‘savanna baboons’ because they usually live in savanna-woodland habitats. The term ‘savanna baboon’, however, says nothing about what species of baboon it is, for two reasons: (1) multiple species of baboons live in savanna habitats and are thus called 'savanna' baboons, and (2) within each species, some populations live in savanna habitats whereas others do not. For example, while many olive baboons live in the savannas of East Africa, many olive baboons also live in the tropical forests of West Africa. Similarly, while some chacma baboons live in savanna-like habitats of southern Africa and are called 'savanna baboons', others live in the Drakensberg mountains of South Africa and are called ‘mountain baboons', while still others live in the arid regions of Namibia and are called ‘desert baboons’. The term 'desert baboon' has also been used for hamadryas baboons, which inhabit the semi-deserts of Ethiopia and the southwestern Arabian Peninsula.
Diet and Feeding. Baboons are omnivorous and opportunistic in their feeding, which means they will eat almost anything and will change their diets as the environment around them changes. Baboon diets include a combination of fruit, flowers, seeds, pods, leaves, gum, and underground storage organs from a wide array of plant taxa as well as almost any small animal that they can catch (Hall 1962a; DeVore and Washburn 1963; Rowell 1966; Altmann and Altmann 1970; Harding 1975; Davidge 1978b; Hamilton and Busse 1982; Norton et al 1987; Whiten et al 1987, 1991; Altmann 1998). Baboons are also adaptable foragers, sometimes dramatically changing their diets in response to changes in available resources (e.g., Hamilton et al 1978). They will also readily feeding on human-produced garbage (see section on Flexibility and Commensalism for more on this). Many baboons exploit foods that are difficult for smaller monkeys to obtain, including palm nuts and other fibrous fruits (Hamilton et al 1978; Swedell et al 2008) as well as underground plant parts such as corms, bulbs, rhizomes, and tubers that require strength and dexterity to extract (Hall 1962a; Altmann and Altmann 1970; Hamilton et al 1978; Rasmussen, 1978; Post 1982; Whiten et al 1987, 1991). In the Cape Peninsula of South Africa, baboons feed on shellfish, including mussels, limpets, and crabs (Hall 1962a; Davidge 1978b). Thus, baboons are enormously diverse and flexible in their diets, but they are also highly selective in their food choices, with nutrient composition playing a large role in food selection. Baboons typically choose foods that are high in protein and lipids and low in fiber and potential toxins (Hamilton et al 1978; Altmann et al 1987; Norton et al 1987; Whiten et al 1987, 1990, 1991; Johnson 1990; Barton et al 1993; Barton and Whiten 1994; Altmann 1998).
Socioecology. Baboon group sizes – which can range from around 10 to around 200 – vary in predictable ways with both predation risk (e.g., Hill and Lee 1998) and habitat quality, with larger groups of ‘savanna’ baboons, for example, in richer habitats such as the fertile swamps of the Okavango Delta and the smallest in the arid Namib Desert and the highly seasonal Drakensberg mountains. Where food abundance and distribution differ over space and time, temporary subgrouping can occur during foraging (e.g., Aldrich-Blake et al 1971; Homewood 1976; Anderson 1981b, 1982; Horn 1987a; White 2007). Thus, baboon group sizes may be very small or very large depending on environmental conditions (for more, see: Dunbar 1992, 1993a; Barton et al 1996; Bronikowski and Altmann 1996; Barton 2000; Hill and Dunbar 1998, 2002; Henzi and Barrett 2003, 2005; and Alberts and Altmann 2006).
Habitat Use. The size of a baboon troop's home range (i.e., the area it uses) and its travel patterns (how it moves around during each day) are influenced mainly by the distribution of food resources, water sources (in drier habitats), and suitable sleeping sites. In moister environments, baboons can often get as much water as they need from plants, and water sources are thus less important in those habitats. As resource quality decreases, home range size and daily path lengths increase, thus baboons have larger home ranges in less productive, drier habitats. Sleeping sites for baboons are most commonly cliffs or trees, but they have also been known to sleep in caves or under rocky overhangs (Hall 1962a; Bert et al 1967; Altmann and Altmann 1970; Hamilton 1982; Anderson and McGrew 1984; Barton et al 1992; Barrett et al 2004; Schreier and Swedell 2008).
Activity Patterns. Baboons in lower-quality habitats spend more time feeding and foraging than those in higher-quality habitats (Hall 1962a, Whiten et al 1987; Norton et al 1987; Bronikowski and Altmann, 1996; Barrett et al 2006; Swedell et al 2008). Hill et al (2003) demonstrated that activity budgets in baboons can be at least in part predicted by the mean annual temperature, suggesting that thermoregulation plays a large role in baboon behavior. For example, yellow baboons at Amboseli in Kenya spend more time resting in years with greater daily maximum temperatures (Bronikowski and Altmann 1996), and desert chacma baboons are far less active during intergroup encounters after several days of water deprivation (Brain 1991). Baboons living in hot climates in fact adjust their activity levels and postures to changes in temperature and solar radiation in ways that suggest that they actively thermoregulate (Stelzner and Hausfater 1986; Stelzner 1988; Hill 2006). In the Namib Desert, baboons ‘sandbathe’, apparently to lower body temperature (Brain and Mitchell 1999).
Seasonality and Stress. Diets vary seasonally in many baboon populations, with fallback foods (readily available but lower in nutritional value) replacing preferred foods during the dry season or winter months (Kummer 1968a; Altmann and Altmann 1970; Norton et al 1987; Whiten et al 1987; Hill and Dunbar 2002; van Doorn et al 2010). In some populations, fewer plant species are consumed during the dry season compared to the wet season, reflecting the reduced food supply (Post 1982; Norton et al 1987; Swedell et al 2008). In the Drakensberg of South Africa where the dry season corresponds with winter, one troop of chacma baboons migrated to higher altitudes during the summer (and wetter) months and to lower altitudes during the winter (and drier) months (Whiten et al 1987). In extreme environments such as the Drakensberg, thermoregulatory and nutritional stress during the cold, dry winters appears to force baboons to lower elevations on a seasonal basis (Whiten et al 1987; Henzi et al 1992) and increase levels of stress hormones (Weingrill et al 2004). At Amboseli, thermoregulatory (heat) stress as well as nutritional stress during the dry season is similarly associated with higher levels of stress hormones among females (Gesquiere et al 2008).
Altitude. Social structure and activity budgets vary with reduced food availability and climatic extremes at high altitudes such as the Drakensberg in South Africa. Whiten et al (1987) and Byrne et al (1987) found an inverse relationship between altitude and group size in chacma baboons in the Drakensberg, i.e., smaller groups are found at higher altitudes and vice versa. Although Henzi et al (1990) found no such relationship in this population, it nevertheless appears that at higher altitudes under conditions of nutritional stress, baboons are found in either smaller group sizes and/or lower population densities (Byrne et al 1993).
Territoriality. Baboons are generally not territorial, and home ranges of neighboring troops usually overlap, sometimes extensively. Northern populations of chacma baboons, however, have been reported to defend territorial boundaries in a desert habitat in Namibia and in the Okavango Delta in Botswana where population densities were relatively high (Hamilton et al 1976).
Predators. Observed predators of baboons and their closest relatives, other African papionin monkeys (e.g., mangabeys), include crowned hawk-eagles (Stephanoaetus coronatus), Central African rock pythons (Python sebae), leopards (Panthera pardus), lions (Panthera leo), spotted hyaenas (Crocuta crocuta), and humans (Altmann and Altmann 1970; Horn 1987a; Fischer et al 1999-2000; Davenport et al 2006; Paterson 2006).
Content contributed by:
Dr Larissa Swedell
|Thanks to the following reviewers:
Dr Susan Alberts
Dr Cliff Jolly
photographs by L. Swedell
For a more scholarly version of the information on these pages, see:
Swedell, L (2011) African Papionins: Diversity of Social Organization and Ecological Flexibility. IN Primates in Perspective, Second Edition (Campbell CJ, Fuentes A, MacKinnon KC, Bearder SK, Stumpf, RM, eds). New York: Oxford University Press, pp. 241-277.
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