Marion L. East

Bushmeat hunting by communities adjacent to the Serengeti National Park, Tanzania: the importance of livestock ownership and alternative sources of protein and income

Illegal hunting of resident and migratory herbivores is widespread in the Serengeti National Park, Tanzania. To devise effective strategies to reduce levels of hunting, information is required on why people are involved in illegal hunting and the role of bushmeat in the local economy. Participation in hunting may be influenced by measures of relative wealth, including livestock ownership, means of generating cash income and access to alternative sources of meat. Data came from 300 individuals responding to a questionnaire in 10 villages, from responses by 359 people in 24 group discussions in another 12 villages, and from 552 people arrested and interviewed in the National Park. A smaller proportion of individual respondents (32%) than group respondents (57%) volunteered that they participated in illegal hunting. Most individual and group respondents were subsistence farmers who considered bushmeat to be a source of protein and a means of generating cash income. Three-quarters of those arrested participated in hunting primarily to generate cash income and a quarter claimed that they only hunted to obtain food. Participation in illegal hunting decreased as wealth in terms of the number of sheep and goats owned increased. People with access to alternative means of generating income or acquiring protein were also less likely to be involved in illegal hunting. Arrested respondents were typically young adult males with low incomes and few or no livestock. Illegal hunting was not reduced by participation in community-based conservation pro-grammes. Results suggested that between 52 000 and 60 000 people participated in illegal hunting within protected areas, and that many young men (approximately 5200) derived their primary source of income from hunting.

The erect 'penis' is a flag of submission in a female-dominated society: greetings in the Serengeti spotted hyaenas

In East Africa, spotted hyenas live in large clans in a highly structured society dominated by females. A clan is a fission-fusion society where members are often solitary or in small groups. Spotted hyenas have a ritualized greeting during which two individuals stand parallel and face in opposite directions. Both individuals usually lift their hind leg and sniff or lick the anogenital region of the other. The unique aspect of greetings between individuals is the prominent role of the erect ‘penis’ in animals of both sex. Female spotted hyenas have fused outer labiae and a ‘pseudo-penis’ formed by the clitoris which closely resembles the male penis and can be erected. During greetings subordinates signalled submission with gestures which were not necessarily reciprocated by the dominant participant. Asymmetries were most pronounced in greetings between adult females where the probability of asymmetries increased with the divergence in rank between partners. Greetings between adult females and males were uncommon and restricted to males above median rank, principally the alpha male. Models of primate affiliative behavior assume that benefits derived from social relationships with different individuals are not equal and that individuals are selected to maximize the benefits they receive from social relationships with others. The observed distribution of greetings between partners of different rank matched the predictions of these models. An examination of non-adaptive hypotheses on the evolution of the ‘pseudo-penis’ demonstrated that the conventional scenario linking (initial) virilization of female genitalia with selection for female dominance does not explain either the initial virilization, nor the evolution of the ‘pseudo-penis’ to its current form and use. We sketch a new scenario that links (1) initial virilization to the occurrence of neonatal siblicide amongst members of a twin litter, and (2) costs of maintenance, ‘pseudo-penile’ control over copulation and male submission. Our analysis confirms previous adaptive hypotheses on the function of the ‘pseudo-penis’ in greetings and suggests new hypotheses to account for hitherto unexplained features.

Loud calling in a female-dominated mammalian society: II. Behavioural contexts and functions of whooping of spotted hyaenas, Crocuta crocuta

Abstract Spotted hyaenas use a loud call, the whoop. In this study, whoops served three main functions: (1) to display identity; (2) to request support; and (3) to convey information about the location of the caller. An analysis of ontogenetic changes revealed a common functional framework of loud calling for cubs and adults. Cubs primarily whooped to provide information about their location and to request support, while adults mainly whooped to display their identity, males more so than females. Females whooped during agonistic encounters with other female clan members and clashes with neighbouring clans, when locating offspring and when rallying group members to defend communal resources. Whooping in males was mainly used for inter- and intra-sexual display. Self-advertisement (vocal display) was the most common function of whooping at the communal den. Both sexes displayed vocally, but males called at higher rates than females. High-ranking females displayed vocally at a higher rate than subordinates to assert their priority of access to kills in the clans core range. Breeding females also whooped to deter potentially infanticidal non-clan members from approaching cubs at the communal den. Spotted hyaenas are polygynous, and male vocal display rates are an important component of inter-male competition. Display rates may also influence mate choice by the dominant and more aggressive females. Dominant males exerted more effort when whooping than subordinates by having higher display rates, more often using the energetically more costly type S whoop, and producing more calls per bout. All top ranked males are old, and have probably held long tenure in the clan. If females only mate with dominant males they may select mates on the basis of age, familiarity, display effort or a combination of these factors.

Biological conservation and stress

Publisher Summary This chapter considers the problem of defining stress and its relevance to conservation. The chapter discusses the way in which an evolutionary framework can be incorporated into studies of stress that are relevant for conservation. It reviews how stress has been studied and develops a set of criteria to evaluate published work. The natural history of stress is also reviewed—in particular, factors influencing inter- and intrapopulation variation in the stress response—and elements of a theory of stress in biological conservation are outlined. The chapter surveys the indicators of stressed states and discusses the potential of anthropogenic environmental factors—such as pollution, disturbance, hunting, noise, and climatic (global) warming—to cause stress and evaluates whether stress responses to these anthropogenic stimuli can be equated to natural stress stimuli. It also considers whether research and conservation activities should be considered potential stressors. Actions that minimize the occurrence and impact of stress in conservation research and management are discussed. The chapter shows that such actions readily fall into two categories: minimizing the occurrence of stress and maximizing the ability of individuals to cope successfully with stress.

Behavioral processes and costs of co-existence in female spotted hyenas: a life history perspective

We assessed the importance of three behavioral processes on the fitness of individual females as mediated via maternal care in matrilineally organized social groups of spotted hyenas Crocuta crocuta. These were maternal choice of foraging tactic, the maintenance of individual dominance rank (social status) within the adult female hierarchy, and the behavioral support provided by mothers to their daughters when daughters acquired their position in the adult female hierarchy. The effects of all behavioral processes were closely linked. Maternal care was dependent on maternal social status because high ranking females had priority of access to food, and individual maternal choice of foraging tactic was frequency – and social status-dependent when medium prey abundance provided an opportunity for such a choice. At medium prey abundance, low ranking females went on costly long distance commuting trips to forage on migratory herds outside the group territory, whereas high ranking females fed on kills within the group territory. As a consequence, offspring of high ranking females grew faster, had a higher chance of survival to adulthood, and thus high ranking females had a higher lifetime reproductive success. Daughters of high ranking females usually acquired a social status immediately below that of their mother provided they enjoyed the effective support from their mothers as coalition partners, and they gave birth to their first litter at an earlier age than daughters of low ranking mothers. Spotted hyenas are therefore an example of the ‘silver-spoon effect’. This study shows that the frequency-dependent outcome of behavioral processes can be a key determinant of maternal reproductive success in social carnivores and have a profound influence on the reproductive career prospects of offspring.

Regular exposure to rabies virus and lack of symptomatic disease in Serengeti spotted hyenas

We report a previously unrecognized complexity to the ecology of rabies in wildlife. Rabies-specific virus-neutralizing antibodies in spotted hyenas, the most numerous large carnivore in the Serengeti ecosystem (Tanzania, East Africa), revealed a high frequency of exposure of 37.0% to rabies virus, and reverse transcriptase (RT) PCR demonstrated rabies RNA in 13.0% of hyenas. Despite this high frequency, exposure neither caused symptomatic rabies nor decreased survival among members of hyena social groups monitored for 9 to13 years. Repeated, intermittent presence of virus in saliva of 45.5% of seropositive hyenas indicated a “carrier” state. Rabies isolates from Serengeti hyenas differed significantly (8.5% sequence divergence) from those isolated from other Serengeti carnivores, suggesting that at least two separate strains circulate within the Serengeti carnivore community. This finding is consistent with the fact that exposure in hyenas increased with age and social status, following a pattern predicted by intraspecific age and social-status-dependent oral and bite contact rates. High seroprevalence of rabies, low basic reproductive rate of the virus (R0) of 1.9, a carrier state, and the absence of symptomatic rabies in a carnivore in an ecosystem with multihost and multistrain maintenance has not been previously demonstrated for rabies. Because of the substantial differences between the hyena viral isolates and those from canids and viverrids in the Serengeti, it is unlikely that spotted hyenas were the source of rabies virus that killed several African wild dog packs in the Serengeti ecosystem in the 1990s.

Genetic characterization of canine distemper virus in Serengeti carnivores

The lion (Panthera leo) population in the Serengeti ecosystem was recently afflicted by a fatal epidemic involving neurological disease, encephalitis and pneumonia. The cause was identified as canine distemper virus (CDV). Several other species in the Serengeti were also affected. This report presents CDV H and P gene sequences isolated from Serengeti lions (Panthera leo), spotted hyenas (Crocuta crocuta), bat-eared fox (Otocyon megalotis) and domestic dog (Canis familiaris). Sequence analyses demonstrated that the four Serengeti species carry closely related CDV isolates which are genetically distinct from other CDV isolates from various species and locations. The results are consistent with the conclusions that: (1) a particularly virulent strain of CDV emerged among Serengeti carnivores within the last few years; (2) that strain has recognizable shared-derived (synapomorphic) genetic differences in both H and P genes when compared to CDV from other parts of the world; and (3) that the CDV strain has frequently crossed host species among Serengeti carnivores.

Demography, Extinction and Intervention in a Small Population: the Case of the Serengeti Wild Dogs

The effects of ecological factors (prey, competitors, predators and disease) and intervention (immobilization, radio-collaring, and vaccination) on population size and demography were investigated in Serengeti wild dogs (Lycaon pictus), an endangered canid, between 1965 and 1991. Variation in ecological factors explained most changes in demography, but did not explain a decline in adult longevity. A significant reduction in pack life and individual longevity was coincident with the introduction of routine intervention and consistent with pathogen-induced mortality. Survival varied significantly between categories of intervention, and between individuals likely to have been exposed to different degrees of social stress before intervention. The loss of all study packs in 1991 contrasted with the persistence of breeding packs outside the study area. The cause of the demise of most study packs is unknown. Monte Carlo simulations demonstrated that population extinction was unlikely to be the consequence of chance events alone. One explanation compatible with the evidence is an outbreak of viral disease induced by stress, possibly caused by intervention.

Sexual conflicts in spotted hyenas: male and female mating tactics and their reproductive outcome with respect to age, social status and tenure.

We investigated the reproductive outcomes of male and female mating tactics in the spotted hyena, Crocuta crocuta, a female–dominated social carnivore with high maternal investment, an absence of paternal care and female control over copulation. Paternity was determined using microsatellite profiling of 236 offspring in 171 litters from three clans. We found little evidence that male tactics that sought to coerce or monopolize females were successful. Polyandry and sperm competition appeared to counter effectively pre–copulatory male tactics, such as harassment, monopolization and other tactics, such as infanticide, that were against the evolutionary interests of females, and may have contributed to the stability of the male dominance hierarchy, which operated as a social queue. At least 39% of 54 females mated multiply, and 35% of 75 twin litters were fathered by two sires. Polyandry may also serve to ensure fertilization, compensate for an initial poor–quality mate or ensure fertilization by genetically compatible mates. Female mate choice matched observed patterns of affiliative male–female behaviour, indicating that affiliative behaviour is a successful male mating tactic, and was consistent with the idea that male tenure may serve as an index of male quality, although male fertility may decline with extreme old age.

Female mate-choice drives the evolution of male-biased dispersal in a social mammal

Dispersal has a significant impact on lifetime reproductive success, and is often more prevalent in one sex than the other. In group-living mammals, dispersal is normally male-biased and in theory this sexual bias could be a response by males to female mate preferences, competition for access to females or resources, or the result of males avoiding inbreeding. There is a lack of studies on social mammals that simultaneously assess these factors and measure the fitness consequences of male dispersal decisions. Here we show that male-biased dispersal in the spotted hyaena (Crocuta crocuta) most probably results from an adaptive response by males to simple female mate-choice rules that have evolved to avoid inbreeding. Microsatellite profiling revealed that females preferred sires that were born into or immigrated into the female’s group after the female was born. Furthermore, young females preferred short-tenured sires and older females preferred longer-tenured sires. Males responded to these female mate preferences by initiating their reproductive careers in groups containing the highest number of young females. As a consequence, 11% of males started their reproductive career in their natal group and 89% of males dispersed. Males that started reproduction in groups containing the highest number of young females had a higher long-term reproductive success than males that did not. The female mate-choice rules ensured that females effectively avoided inbreeding without the need to discriminate directly against close kin or males born in their own group, or to favour immigrant males. The extent of male dispersal as a response to such female mate preferences depends on the demographic structure of breeding groups, rather than the genetic relatedness between females and males.