Carnivores show a strength in diversity, with their fascinating social systems and different hunting behaviours. Numerically, however, they are weak, compared with other animals. Nevertheless, despite their small numbers, they have an effect on people that is out of all proportion to their abundance. In order to analyse this in some detail, I will start at the darkest, most horrifying and negative side of our relationship with the animals, that is their predation on us. They can be very dangerous enemies.

For obvious reasons conservationists often deny that large predatory animals actually kill people, but there is ample evidence that such indignant denial is nonsense. We will see in this chapter that there are considerable numbers of carnivores that actually prey on us. The details of such predation are often anecdotal, and I will present them as such, but these occurrences are nevertheless real, and as my former teacher Niko Tinbergen used to say, many anecdotes make a statistic.

The stories are bloody, and some readers may be put off by the gory detail. Such a reaction is part of our anti-predator behaviour. But I think that the pattern of predation is important, as is how common the incidents are, because this is what makes up the threat which, in evolution, has shaped our response to predators. Amongst other things, we want to know whether any group of carnivores is more of a threat to us than others and if so, how these animals operate.

PETS IN PAST AND PRESENT

In November 1997 the then President of the USA acquired a dog, just an ordinary dog, and it was the first time the man had ever had one. The animal made headlines all over the world, and the acquisition was seen rather cynically as a major attempt by Bill Clinton to improve his image amongst the populace. One remembered President Truman's observation that ‘if you want a friend in Washington, get a dog’. Only a few presidential terms before Clinton, pictures in the media of Lyndon Johnson pulling the ears of his canine companion had contributed significantly to his subsequent loss in the election. George Washington owned 37 dogs, and almost every president since then has had at least one. Also, the British royal family is often pictured surrounded by an entourage of corgis. Obviously, image-makers are in no doubt that pets have a very significant influence on the perception people have of each other at all levels of our society, and Clinton was a late learner.

All this is based on people's deep love of pets. Of course, they are not to everybody's liking, but for most of us dogs or cats are almost as close to our hearts as are other people, and someone who is nasty to a dog is an enemy. We look them in the eyes, love the feel of their coat, and we play with them almost as with children.

Now, at the turn of the millennium we are seeing animals, especially carnivores, from a perspective that is very different from the one we had before. Our views are changing, and this is a process that is going remarkably fast. Let me give an example.

In the late 1960s the magazine Life featured a set of spectacular photographs of a leopard catching and killing a baboon, in Africa. The pictures showed every detail of the sinewy predator in the African bush, the blurred, lightning-speed action, and the intensely frightened expression on the face of the baboon at the final moment. The photographs were stunning, almost literally so because they were so excellent that one identified totally with the victim. Later, it became known that the entire scene in those photographs was set up. The leopard was a tame animal, the pictures were taken on a ranch in Kenya, six baboons were bought from an enterprise that provided primates for medical experiments. The photographer sat in a vehicle that was being driven alongside the leopard, and the baboons were thrown in front of the leopard from the vehicle.

Such deliberate and horrible cruelty for the sake of a picture is unlikely to happen today, only 30 years later, because the western world just would not knowingly allow it. People now object strongly to such inhumane treatment, and in many countries there are laws to prevent it.

Previous chapters showed carnivores as a dangerous and expensive nuisance, but it would go against the grain to leave it at that. They are highly attractive animals, and if that is not enough, wild carnivores can also be tremendously useful to us. In this chapter I will discuss some of their direct, material benefits – often more of historical significance than of present-day importance, but nevertheless far-reaching aspects of our ecological relationship with carnivores.

Some time ago I gave a talk here in my Scottish village, and when it came to the conservation of otters, a somewhat grumpy farmer asked ‘what is the use of them to me?’ He was, of course, implying that otters and their conservation are a waste of time. To many people, like me, otters are of use, simply because we are thrilled if we see them, and even if we do not actually come across an otter we enjoy the knowledge that we might, and that they are there in the river or the lake. People are even prepared to pay for this pleasure. Nevertheless, the farmer's utilitarian question is central to society's approach to the environment. Can we eat them, use their products, or do they provide a sport or service? In the end it is this question that will determine the survival of many of these species.

CARNIVORES AS FOOD

In modern western society we do not eat carnivores any more; even the idea is rather repulsive.

Getting close to a wild carnivore can be an emotional experience, whether it be a fox or a lion. One feels that unique adrenalin-based chill in the spine, a slight fear, the overwhelming thrill of the animal's proximity and the knowledge of its abilities, its sharp teeth, speed and its strength, its possible aggression and the question of what it will do next.

Such an emotional response stems from our basic instincts about animals, and particularly about carnivores. These instincts are innate in even the most urbanized of people, and must have evolved to meet the fundamental ecological challenge of predators to our survival. In previous chapters I have discussed details of these threats from carnivores to ourselves and other animals. Here I want to describe the behaviour of a variety of species, including people, that are targets for predators, behaviour that we see in response to such threats.

The ecological effects of carnivores on ourselves, and on almost all mammals and birds have been, and still are, considerable. The next question, then, is about the behavioural response: exactly how do birds and mammals protect themselves? Do they learn how to cope with danger, and/or is there innate behaviour that evolved in response to selection pressures from predators? Seeing the vast range of beautifully adaptive behaviour patterns in animals facing all kinds of environmental challenges, one could also expect many behavioural adaptations to protect against the threat of predation.

The participation in a stalk, in a long chase, in the battle with a victim and seeing its hairbreadth escape, all this must always have been one of the great excitements that life has to offer, right from the beginning of our existence as a species. We may experience this at first hand, as hunters ourselves, or by proxy in front of the TV. But even those who themselves are not hunters in some way or other, and people who disapprove of hunting as an activity for Homo sapiens, cannot help but be keenly interested in (although perhaps horrified by) the drama of a hunt and its outcome. Carnivores have an unsurpassed expertise as hunters, which is one of the big attractions of the animals for us: they demonstrate the ultimate skill in deciding over the lives of others. The behaviour of a carnivore, the ‘life of the hunter’, is a subject of endless fascination, sometimes even envy.

Part of this allurement may be due to us identifying with either the prey or the hunter. Perhaps we feel instinctively that what we observe of the hunting process may be useful some day, as it would have been in the early stages of human evolution. How do these role models, potential predators on ourselves and competitors, relate to their environment, especially to their potential prey animals?

INTRODUCTION

Scenarios of ape–human divergence have often represented hominins as savanna-adapted (e.g. Dart 1959; Robinson 1972; Coppens 1988; Wheeler 1992), whereas the chimpanzee (Pan troglodytes) has been represented as rainforest-adapted. This dichotomy has eroded from both sides of the divide. Kano (1972) and McGrew et al. (1981) noted that the longest-studied chimpanzees, those at Gombe and Mahale, live in a grassland–woodland–forest mosaic, not tropical forest, and that other populations range into even drier, more open habitats (see the ‘savanna ape model’ in Moore 1996). The habitats of the earliest hominins were at least partly forested (Bonnefille 1984; WoldeGabriel et al. 1994, 2001). A less severely drawn contrast between ape and hominin habitats now seems a better fit with the evidence: Chimpanzee habitats range from closed-canopy rainforest to savanna, whereas early hominins likely occupied somewhat drier habitats, ranging from forest to woodland to savanna. This overlap means that primatologists can study the behavior of chimpanzees living in habitats nearly identical to those in which Mio-Pliocene hominins lived.

Study of chimpanzee diet, habitat use, ranging, and positional behavior in peripheral habitats will help establish whether water availability, food availability, food dispersion, vegetative cover, or climate limits the pan-African chimpanzee distribution. Better understanding of the factors that limit chimpanzees may help to identify niche differences between Mio-Pliocene apes and hominins.

Study of chimpanzees at the edges of the species' range may also have conservation implications. Documentation of the minimum requisites of the species is valuable for rehabilitation, relocation, and green corridor projects.

A BRIEF HISTORY

In the late 1950s, the great anthropologist Louis Leakey searched for a student to study wild chimpanzees in their natural habitat; he was convinced that this kind of investigation would provide important information about the behaviour of our early ancestors. His quest eventually ended with Jane Goodall, who began her research on chimpanzees in Gombe in the early 1960s, near the shore of Lake Tanganyika in Tanzania, East Africa.

During the course of the following years, our knowledge of wild chimpanzees relied almost exclusively on observations collected from two communities – Goodall's work at Gombe, and the work of Toshisada Nishida and his colleagues, conducted in Mahale Mountains National Park, some 200 km south of Gombe. Both populations, located on the eastern side of Lake Tanganyika, live in relatively similar environments, characterised by a mosaic of savanna, woodland and dense shrub habitats. The last three decades of the 20th century saw the success of these two studies turn the Tanzanian chimpanzee into something of a prototype for ‘The Wild Chimpanzee’, and behavioural diversity was restricted to the differences between these two populations. Anthropological and psychological literature and textbooks are still strongly biased in assuming that Tanzanian chimpanzee behaviour represents all chimpanzees.

INTRODUCTION

Chimpanzees and bonobos are generally similar in their adult heterosexual behavior. In both species, copulations are largely restricted to females with maximally tumescent swellings (Furuichi 1987; Wallis 1992; Takahata et al. 1996). ‘Group mating’ is the predominant pattern. Rates of copulation vary, but there tend to be several hundred copulations per conception (Goodall 1986; Kano 1992). Furthermore, in both species the relationship between male rank and copulation rate varies in similar ways depending on group composition. Sometimes there is no relationship between a male's dominance rank and his copulation rate (e.g. Gombe chimpanzees: Tutin 1979; Mahale chimpanzees (1980–82,1991): Hasegawa & Hiraiwa-Hasegawa 1990; Nishida 1997; Taï chimpanzees: Boesch & Boesch-Achermann 2000; Wamba bonobos, E1 and E2 1986, P 1988: Takahata et al. 1996). However when a community or party contains few adult males in a stable hierarchy, higher-ranking adult males can achieve more copulations than lower-ranking males (Gombe chimpanzees in 1973–74: Goodall 1986; Mahale chimpanzees in 1992, Nishida 1997; Wamba E-group bonobos 1979: Kano 1996; Lomako bonobos: Gerloff et al. 1999). Dominant males then gain their advantage partly by interfering, at least occasionally, with subordinates' copulations (e.g. in 7% of bonobo copulations, Kano 1992).

Despite such similarities, heterosexual activity also varies in significant ways. A prominent example is the number of sexual cycles per conception, which ranges from an average of 3.6 for Gombe mothers to an average of 29.2 for Taï mothers. Such differences in sexual cycling have no relation to reproductive rates since the population interbirth intervals are similar in different sites (Takahata et al. 1996; Boesch and Boesch-Achermann 2000; Knott 2001).

INTRODUCTION

Chimpanzees (Pan troglodytes) in all well-studied wild populations hunt a variety of vertebrates and share meat extensively (reviews: Wrangham & Bergmann-Riss 1990; Uehara 1997; Stanford 1998). Meat is a highly valued resource and nutritional reasons presumably explain the origin of hunting, although its exact nutritional significance is unclear. Hunting and meat sharing also have considerable social importance. Two major similarities across chimpanzee populations are that red colobus monkeys (Procolobus badius) are the primary prey species where the two species are sympatric (Goodall 1986; Boesch & Boesch 1989; Uehara 1997; Ihobe & Uehara 1999; Mitani & Watts 1999; Boesch & Boesch-Achermann 2000; Hosaka et al. 2001), and that predation rates vary over time (Mahale: Takahata et al. 1984; Uehara 1997; Hosaka et al. 2001; Gombe: Goodall 1986; Wrangham & Bergmann-Riss 1990; Stanford et al. 1994a; Stanford 1998; Ta: Boesch & Boesch 1989; Kahuzi-Biega: Basabose & Yamagiwa 1997; Kibale: Mitani & Watts 1999). Other aspects of hunting vary considerably across and sometimes within populations. In this chapter, we summarize data on hunting and meat sharing by chimpanzees at Ngogo, in Kibale National Park, Uganda. We focus mostly on hunts of red colobus, by far the most important prey species. We compare our data to those from other sites to highlight questions about hunting and meat sharing that are partly resolved and those that remain open. We summarize results of our earlier analyses of hunting and meat sharing at Ngogo (Mitani & Watts 1999, 2001; Watts & Mitani 2002), and use data collected more recently to update analyses of hunting success, cooperation, and the relationship of meat sharing to mating behavior.

INTRODUCTION

Beginning in the early 1990s, intraspecies behavioural variations across a number of chimpanzee (Pan troglodytes) populations became the focus of increasing attention, and interspecies behavioural variations between chimpanzees and bonobos (Pan paniscus) have been the popular mainstay of bonobo recognition (variations such as female social role, use of social sex, etc.). Interspecies differences (larger groups, less aggression, and morphology) have largely been attributed to ecological variation across species ranges, bonobos having been considered to be isolated in an arboreal existence (MacKinnon 1978; Susman 1979) and restricted to a lowland, dense forest ecology. Behavioural diversity in wild chimpanzees first became evident by comparing tool use in the context of foraging as observed across populations inhabiting broad ecological conditions (McGrew 1992). The study of intraspecies behavioural diversity of bonobos is in its infancy, so ecological differences must be considered. When examining behavioural variation between bonobo study sites, White (1992) considered food provisioning at Wamba and the temporal effects of habituation at Lomako to explain variation.

In the relatively few years of bonobo field research, only two populations have been widely documented: Wamba (00°10′N, 22°30′E) and Lomako (00°50′N, 21°05′E). These two populations are both located within uniformly hot, wet, low-lying and flat topographies sheltered by closed-canopy, moist, evergreen lowland forest vegetation.

INTRODUCTION

Predator–teractions are expected to be dynamic, as the outcome of each interaction depends upon the reactions of the two species and the contextual circumstances. Comparisons of the hunting behaviour of lions living in different environments revealed that selection of prey and hunting success was affected not only by the density of available cover but also by the density of potential prey (Van Orsdol 1984; Packer et al. 1990; Stander 1992). Studies on wild dogs have shown that hunting behaviour is affected by the ecological conditions under which the hunt occurred (Creel & Creel 1995). Similarly, fish modified their hunting behavior depending upon their hunger level as well as the available cover (Milinski 1975). Accordingly, empirical evidence supports the expectations that predator–teractions vary under the influence of different factors, including the behaviour of both opponents, as well as the prevailing spatial conditions. These interactions may also vary over time since species density as well as other environmental factors may vary.

The chimpanzee (Pan troglodytes) is an ideal species in which to examine these interactions, as all well-studied populations have been reported as hunting mammals for meat (Boesch & Boesch-Achermann 2000; Goodall 1986; Uehara et al. 1992; Uehara 1997; Mitani & Watts 1999). In addition, in every long-term study site where red colobus monkeys (Colobus badius) are sympatric with chimpanzees, that is, Mahale and Gombe in Tanzania, Kanyawara and Ngogo of Kibale in Uganda (all in East Africa), and Taï in Côte d'Ivoire (West Africa) this species is the most common prey.

INTRODUCTION

Relationships between individuals are essentially the product of individual efforts to cope with environmentally imposed selection pressures in a social context. They emerge from repeated interactions between individuals, providing the social structure within which the individuals operate (Hinde 1976). In chimpanzees (Pan troglodytes), this structure is especially fluid (Goodall 1965; Reynolds & Reynolds 1965; Nishida 1979). The relationships that an adult male chimpanzee has with other males within his community appear to be both key components in the struggle for high social status within a community, and crucial for successful inter-community territorial encounters (Bygott 1979; Wrangham & Smuts 1980; Wrangham 1986; Nishida & Hosaka 1996; Boesch & Boesch-Achermann 2000). High social status is thought to increase the ability of males to monopolise females and so achieve higher mating success (Sugiyama & Koman 1979; Tutin 1979; Hasegawa & Hiraiwa-Hasegawa 1983). In social situations where a single male may not be able to monopolise access, a pair of males may be able to do so, providing a direct mating benefit to the cooperating males (Goldberg & Wrangham 1997; Watts 1998). Relationships may also provide proximate benefits beyond support in agonistic confrontations, which may, in turn, lead to higher social status, and serve to reduce both social tension and individual stress (Kawanaka 1990; de Waal 1996).

Despite the value of cooperative relationships to male chimpanzees, they appear to show little long-term loyalty to one another and can be extremely fickle in their allegiances (Nishida 1983; Uehara et al. 1994; Nishida & Hosaka 1996).