Social dominance and feeding patterns of spotted hyaenas

In some parts of East Africa, spotted hyaenas (Crocuta crocuta) live in large groups and at high population densities, and scramble competition among clan members during feeding at large carcasses is reported. By contrast, spotted hyaenas in the Namib Desert of southwestern Africa live in small groups and at low densities. When assembled at carcasses, Namib Desert spotted hyaenas show linear dominance hierarchies. Adult females outrank adult males and usually feed one at a time or with their dependent offspring. Feeding rates at small carcasses in the Namib Desert are approximately equal to those reported in East Africa, but at large carcasses Namib Desert spotted hyaenas show linear dominance hierarchies. Adult females outrank adult males and usually feed one at a time or with their dependent offspring. Feeding rates at small carcasses in the Namib Desert are approximately equal to those reported in East Africa, but at large carcasses Namib Desert spotted hyaenas feed significantly more slowly. Thus lower-ranking individuals eventually gain access to large carcasses but are excluded from smaller ones. We relate these patterns of food consumption to possible evolutionary pathways to social hunting by spotted hyaenas.     

A seasonal feast: long-term analysis of feeding behaviour in the spotted hyaena (Crocuta crocuta)

The feeding behaviour of the Talek clan of spotted hyaenas in the Masai Mara National Reserve, Kenya, was monitored continuously for 7 years. Talek hyaenas adapted to large temporal variations in prey abundance by being opportunistic predators. During the first half of the year, the hyaenas fed on resident ungulates, and their diet consisted mainly of topi and Thomson's gazelles. Upon arrival of the migratory herds of wildebeest and zebra from the Serengeti, Talek hyaenas switched to feeding on the wildebeest which provided them with a superabundance of food for about 3 months. After the migratory animals returned to the Serengeti, Talek hyaenas experienced a period of reduced prey abundance due to the temporary dispersion of resident ungulates. At this time hyaenas hunted the few remaining wildebeest, and also increased their use of the remaining resident animals. Although Talek hyaenas were generally opportunistic in their feeding behaviour, they did exhibit clear dietary preference for larger prey species, particularly wildebeest. Finally, carrion comprised only 5% of the biomass consumed by Talek hyaenas, the lowest proportion of carrion in the diet of any Crocuta population studied to date.     

Patterns of scavenger arrival at cheetah kills in Serengeti National Park Tanzania

Scavenging by large‐bodied vertebrates is observed in many ecosystems but has rarely been quantified. Here we document the timing and order of scavenger arrival at 639 cheetah kills in Serengeti National Park, Tanzania, focusing on ecological and heterospecific factors that may impact detectability of carcasses. We found that small‐, medium‐ and large‐sized vultures, jackals, spotted hyaenas and lions were more likely to be present at the carcasses of large‐bodied than small‐bodied prey. Lions and spotted hyaenas were less likely to locate kills in tall grass; medium‐sized vultures were likely to arrive before both large‐ and small‐sized vultures. Spotted hyaenas and vultures were likely to be present at kills simultaneously. Despite numerous anecdotal accounts, we did not find that hyaenas use alighting vultures as a means of locating food. Our findings show that environmental variables and other scavenger species strongly influence scavenger arrival at carcasses in this ecosystem.     

Dyadic associations reveal clan size and social network structure in the fission–fusion society of spotted hyaenas

Estimating the size and dynamics of populations is of paramount importance in ecology. In species with uniquely marked individuals, capture–recapture methods can be used to establish population size and to explore associations between individuals. However, very few studies have used cameras traps to focus on group composition in social carnivores, despite being of particular interest in species characterised by “fission–fusion” formation of sub-groups. Here, we provide estimates of (a) population size, (b) density, (c) clan size, (d) association patterns and (e) social network structure in spotted hyaenas (Crocuta crocuta) based on images from camera traps deployed at waterholes on Ongava Game Reserve (northern Namibia). In a 15 week study period, we identified 32 individuals. Dyadic associations and the resulting social network showed that all but two hyaenas associated directly or indirectly with each other, indicating the presence of one clan of at least 30 individuals, resulting in a density of 8.1 hyaenas/100 km². We found a very high variability in the tendency of individuals to associate with others. This study confirms a highly dynamic fission–fusion society in spotted hyaenas. We argue that camera traps can provide relevant insights into large carnivore social network structure where associations between individuals are difficult to observe directly.     

Feeding ecology and its influence on social organization in Brown hyenas (Hyaena brunnea, Thunberg) of the Central Kalahari Desert

(1) Observations are presented on the diet, feeding habits, hunting and foraging behaviour of Brown hyaenas of the Central Kalahari. (2) The remains of kills left by other predators are the single most important food item in the Brown hyaena's diet. The diet also consists of small scavenged items, small prey such as rodents which the hyaena itself kills, and wild fruits. (3) Brown hyaenas hunt and scavenge small items solitarily, but congregate for communal scavenging of the large kills left by other predators. (4) Individual hyaenas are not territorial and there is great overlap in home ranges. They use common pathways and frequently meet to socialize while foraging. (5) Resident adults form a group with a social hierarchy maintained through neck-biting, muzzle-wrestling, chasing, and other social interactions. Subadult hyaenas often leave the group when approximately 22 months old. (6) Brown hyaenas have a complex system of communication including visual displays, social interactions, vocalizations, and extensive pasting. These are described. (7) Since carrion is an important source of food, Brown hyaenas have developed distinct relationships with other predators and these are described. (8) In conclusion, the Brown hyaena exhibits a highly flexible social system, foraging and hunting small items solitarily and congregating for the common utilization of a large carcass. The social organization is therefore influenced by the feeding ecology.     

Prey preferences of the spotted hyaena (Crocuta crocuta) and degree of dietary overlap with the lion (Panthera leo)

Spotted hyaenas Crocuta crocuta were once considered mere scavengers; however, detailed research revealed that they are very efficient predators. Information on what spotted hyaenas actually prefer to prey on and what they avoid is lacking, as well as the factors that influence prey selection. Data from 14 published and one unpublished study from six countries throughout the distribution of the spotted hyaena were used to determine which prey species were preferred and which were avoided using Jacobs' index. The mean of these values for each species was used as the dependent variable in multiple regression, with prey abundance and prey body mass as predictive variables. In stark contrast to the rest of Africa's large predator guild, spotted hyaenas do not preferentially prey on any species. Also surprisingly, only buffalo, giraffe and plains zebra are significantly avoided. Spotted hyaena most prefer prey within a body mass range of 56–182 kg, with a mode of 102 kg. The dietary niche breadth of the spotted hyaena is similar to that of the lion Panthera leo , and the two species have a 58.6% actual prey species overlap and a 68.8% preferred prey species overlap. These results highlight the flexible and unselective nature of spotted hyaena predation and are probably a reason for the species' success throughout its range, despite a large degree of dietary overlap with lions.     

Optimal hunting group size: the need for lions to defend their kills against loss to spotted hyaenas

This paper presents preliminary evidence that kleptoparasitism by spotted hyaenas may influence optimal hunting group size of lions. In the absence of adult male lions, hyaenas can drive female and subadult lions off their kills provided they outnumber the lions by a factor of four. Hence the larger the group of lions on the kill, the greater their chance of defending their food against invading hyaenas. At Savuti, where there was a shortage of adult male lions, the groups of female and subadult lions lost almost 20% of their food to hyaenas. Losses were most frequent for those living in small groups. These lions were often satiated by the time the hyaenas acquired the kill, so the hyaenas did not cause immediate need, yet constituted a constant energy drain on lions by forcing them to hunt more frequently. The implications of these observations for modelling optimal hunting group size of lions are discussed.     

Resource partitioning among three woodpecker species Dendrocopos spp. during the breeding season

Food composition, prey size utilization and foraging behaviour of three sympatric woodpecker species ( Dendrocopos major, D. medius, D. minor ) were studied in an oak forest near Budapest during the breeding season in 1983 and 1984. Considering these three aspects of feeding, the great spotted woodpecker is a generalist species. Food composition of this species resembled the arthropod supply on the bark of trees more than those of the other two species. The bark of the trees seems to be a relatively unproductive microhabitat in the breeding season, so woodpecker species use, to different degrees, the food supply of the foliage as well. The food and the foraging behaviour of the middle spotted woodpecker show that this species feeds on prey living both on barks and in the foliage; it occupies-an intermediate position between the great and the lesser spotted woodpeckers. Prey size did not correlate with predator size suggesting that woodpeckers adapted not to the summer resources but rather the winter ones.     

Endocrine aspects of sexual mimicry in Spotted hyaenas Crocuta crocuta

Female Spotted hyaenas mimic the male in the possession of a peniform and highly erectile clitoris and false scrotum. Sex hormones have been assayed in the blood plasma, gonads and adrenal glands of male and female Spotted hyaenas and in the blood plasma of Striped and Brown hyaenas. Although the testicular concentration of testosterone greatly exceeds that of the ovaries in Spotted hyaenas, there is no significant difference between the sexes in the mean plasma levels of this hormone, or of the other androgen assayed, andro-stenedione. In contrast, male Brown and Striped hyaenas have far higher plasma concentrations of testosterone than females.
Testosterone levels in twin female Spotted hyaena foetuses were similar to the mean for adult females and it is suggested that high foetal androgen levels are responsible for the appearance of the male sexual facies in adult female Spotted hyaenas. The high plasma androgen levels recorded in adult females may also be associated with their aggression and dominance of males.     

Changes in concentration of serum prolactin during social and reproductive development of the spotted hyaena (Crocuta crocuta).

A homologous radioimmunoassay system developed for humans was used to measure prolactin concentrations in spotted hyaenas. Concentrations of prolactin showed a significant (P < 0.05) decrease in lactating females, which is consistent with the infrequent suckling pattern of this species. This lack of hyperprolactinaemic conditions during lactation may explain the ability of females to resume reproductive activity soon after the loss of a litter, or even during lactation. Prolactin concentrations did not increase significantly during dispersion in male spotted hyaenas. This conforms to the pattern observed for cortisol, but differs from that for androgen, which fluctuates significantly with social suppression. Although comparative data from other species provide some circumstantial evidence for hyperprolactinaemic conditions during male dispersal, no obvious deductions regarding the recorded inverse relationship between prolactin and cortisol concentrations in mature males could be made.     

Foraging Behaviour of the Brown Hyaena (Hyaena brunnea Thunberg, 1820) in the Southern Kalahari

Observations on six free ranging adult brown hyaenas (Hyaena brunnea) fitted with radio collars and beta lights were supplemented by observations on three untagged large cubs and by tracking spoor. Brown hyaenas are predominantly nocturnal and cover large distances alone each night searching for vertebrate remains and other food. Carrion is mainly located by olfactory sense, although auditory cues are also used. Excess food is often stored for short periods. Wild fruits and birds' eggs are eaten and hunting behaviour is directed towards small vertebrates and insects. Some adaptations of the brown hyaena to its environment are discussed.     

Anthropogenic influences on spotted hyaena diet in the Kruger National Park,South Africa

Rapid urban expansion has led to an increase in carnivores that live close to human dominated environments. Some carnivore species have successfully adapted to these novel conditions and taken advantage of opportunities associated with human habitation. Whilst many studies have compared carnivores living in protected areas to those in an urban setting, few have looked at the relationships between carnivores and human habitation within protected areas. In this study, we examined the effects of human habitation on the diet of spotted hyaenas (Crocuta crocuta) in the Kruger National Park (KNP), South Africa. Our results suggested a limited effect of anthropogenic resources on spotted hyaena diet in the KNP. We found neither temporal nor spatial variation in the amount of, nor types of, anthropogenic material in spotted hyaena scats, despite observations of more road side litter close to large anthropogenic sites. We therefore suggest that anthropogenic resources may not have been utilised completely according to abundance. We encourage further research evaluating potential secondary effects of human activity and infrastructure on spotted hyaena diet and also stable isotope approaches that may provide further insights into the importance of anthropogenic food for spotted hyaenas inside the KNP.     

Evidence for prey selection by spotted hyaena in the Eastern Cape,South Africa

We tested the widely accepted hypothesis that spotted hyaenas (Crocuta crocuta) are non-selective in their diet. The prey preference of spotted hyaena was studied in the Addo Elephant National Park (AENP), South Africa. Diet (frequency of occurrence of prey items in the diet) was quantified through the analysis of 55 scats, and compared with available prey. A combination of large- and medium-sized mammals (buffalo (Syncerus caffer), red hartebeest (Alcelaphus buselaphus) and common duiker (Sylvicapra grimmia) were the most preferred prey items. The most abundant species, warthog (Phacochoerus africanus) and kudu (Tragelaphus strepsiceros), were ignored and avoided, respectively. These results show that the assumption that hyaena prey on the most abundant available prey species may be overly simplistic. Predation patterns, such as the ones observed in AENP, may have important ramifications for less common species that are selected by hyaena in small enclosed reserves.     

SPOTTED HYAENA WHOOPS: FREQUENT INCIDENCE OF VOCAL INSTABILITIES IN A MAMMALIAN LOUD CALL

ABSTRACT

Spotted hyaena Crocuta crocuta whoops are loud calls normally produced in a sequence termed a bout. Whoops are produced by hyaenas irrespective of age or sex to display identity and convey information about the location of the caller. The majority (91%, n=460) of whoops produced by spotted hyaenas, from two geographically separate populations in southern Africa and one population in eastern Africa, showed pronounced nonlinear phenomena, predominantly subharmonics. Whoops produced by males and females had a similarly high probability of sub- harmonics, and 91.5% of the 78 bouts examined contained calls with subharmonics. These results provide evidence that nonlinear vocal phenomena are a common feature of hyaena whoops. The presence of subharmonics in whoops may be enhanced by vocal tract resonances when the fundamental frequency and first formant in the calls are close or coincide. Vocal membranes may also play a role. The high incidence of subharmonics in whoops may enhance individual recognition by adding structural complexity to calls. As 33 of 34 individually known spotted hyaenas examined in this study produced whoops containing subharmonics, it is unlikely that the production of subharmonics is confined to calls from individuals of a particular social status, sex, size, or level of developmental asymmetry, as proposed for nonlinear phenomena in the calls of other mammalian species, although variation in structural features of subharmonics may convey information about these characteristics.     

The Lion King and the Hyaena Queen: large carnivore interactions and coexistence

Interactions among species, which range from competition to facilitation, have profound effects on ecosystem functioning. Large carnivores are of particular importance in shaping community structure since they are at the top of the food chain, and many efforts are made to conserve such keystone species. Despite this, the mechanisms of carnivore interactions are far from understood, yet they are key to enabling or hindering their coexistence and hence are highly relevant for their conservation. The goal of this review is thus to provide detailed information on the extents of competition and facilitation between large carnivores and their impact in shaping their life histories. Here, we use the example of spotted hyaenas (Crocuta crocuta) and lions (Panthera leo) and provide a comprehensive knowledge of their interactions based on meta‐analyses from available literature (148 publications). Despite their strong potential for both exploitation and interference competition (range and diet overlap, intraguild predation and kleptoparasitism), we underline some mechanisms facilitating their coexistence (different prey‐age selection and scavenging opportunities). We stress the fact that prey abundance is key to their coexistence and that hyaenas forming very large groups in rich ecosystems could have a negative impact on lions. We show that the coexistence of spotted hyaenas and lions is a complex balance between competition and facilitation, and that prey availability within the ecosystem determines which predator is dominant. However, there are still many gaps in our knowledge such as the spatio‐temporal dynamics of their interactions. As both species' survival becomes increasingly dependent on protected areas, where their densities can be high, it is critical to understand their interactions to inform both reintroduction programs and protected area management.     

Activity patterns of reintroduced lion Panthera leo and spotted hyaena Crocuta crocuta in the Addo Elephant National Park, South Africa

Africa's large predator guild competes for a limited food resource base. To minimize the degree of competition, we hypothesized that the two largest members of this guild and its fiercest competitors, the lion and the spotted hyaena, would partition their activity patterns to avoid interacting. We used 96‐h continuous follows of focal animal(s) to determine when the six radio‐collared lions and eight radio‐collared spotted hyaenas, reintroduced into Addo Elephant National Park in 2003/2004, were active using a binomial measure of activity which was defined as movements >100 m during each hourly period. Contrary to our predictions, lions and hyaenas did not partition their activity times, probably because of their current low population densities. Both species exhibited a crepuscular activity pattern although hyaenas were far less active during daylight. A sub‐adult lioness minimized competitive interactions by becoming diurnal. This is likely to be a common strategy for lions that have been expelled from their natal pride to become nomadic, as it allows them to minimize kleptoparasitic and agonistic interactions from competitively dominant conspecifics and competitors. The increase in testosterone that occurs in males upon reaching sexual maturity, darkens their pelage and causes them to be more directly impacted by the heat, and thereby affords females an opportunity to escape from males during hot temperatures. Similarly, the longer pelage of young hyaenas restricts their activity to the cooler night‐time.     

Association of seasonal reproductive patterns with changing food availability in an equatorial carnivore, the spotted hyaena (Crocuta crocuta).

Reproductive seasonality was examined in an equatorial population of free-living spotted hyaenas (Crocuta crocuta) in Kenya. The study population was observed continuously for 10 years, during which time the dates of all births, conceptions, weanings, and cub deaths were recorded. Local prey abundance was estimated two to four times per month, and rainfall was recorded daily throughout the study period. Births occurred during every month of the year, but a distinct trough in births occurred from February to May. This trough occurred approximately one gestation period after the phase of the annual cycle during which prey animals were least abundant in the home range of the hyaenas, and conceptions occurred most frequently when food abundance was greatest. Neither rainfall nor cub mortality were correlated with births or conceptions. Thus, although spotted hyaenas are capable of breeding throughout the year, they exhibit a moderate degree of seasonality that most likely reflects responses to seasonal variation in energy availability.     

The scent-marking behaviour of the spotted hyaena Crocuta crocuta in the southern Kalahari

All hyaenas scent mark their territories by smearing grass stems with paste from their subcaudal scent glands and by depositing faeces at latrines, but they adopt different strategies in terms of how they disperse these scent marks in their territories. For example, brown hyaenas living in the southern Kalahari deposit pastes and latrines throughout the whole of their territory, while spotted hyaenas living in the Ngorongoro Crater of East Africa place their scent marks strictly along the territorial borders. We have argued elsewhere (Gorman & Mills, 1984) that these different strategies are not species-specific but are instead adaptive responses to local conditions. Here, we use data from a population of spotted hyaenas, living in small clans and large territories in the Kalahari, to test the hypothesis that hinterland marking is a response to the problem of marking a very large territory with a limited amount of scent and within a limited time budget.     

Mechanisms of maternal rank 'inheritance' in the spotted hyaena, Crocuta crocuta

Maternal rank 'inheritance', the process by which juveniles attain positions in the dominance hierarchy adjacent to those of their mothers, occurs in both cercopithecine primates and spotted hyaenas. Maternal rank is acquired in primates through defensive maternal interventions, coalitionary support and unprovoked aggression ('harassment') directed by adult females towards offspring of lower-ranking individuals. Genetic heritability of rank-related traits plays a negligible role in primate rank acquisition. Because the social lives of Crocuta and cercopithecine primates share many common features, we examined whether the same mechanisms might operate in both taxa to promote maternal rank 'inheritance'. We observed a large clan of free-living spotted hyaenas in Kenya to test predictions of four mechanistic hypotheses. Hyaena rank acquisition did not appear to be directly affected by genetic heritability. Unprovoked aggression from adult female hyaenas was not directed preferentially towards low-ranking cubs. However, high-ranking mothers intervened on behalf of their cubs more frequently and more effectively than low-ranking mothers. Maternal interventions and supportive coalitions appeared to reinforce aggression directed at 'appropriate' conspecific targets, whereas coalitionary aggression directed at cubs apparently functioned to extinguish their aggressive behaviour towards 'inappropriate' targets. Young hyaenas and primates thus appear to 'inherit' their mothers' ranks by strikingly similar mechanisms. Copyright 2000 The Association for the Study of Animal Behaviour.     

Surplus killing by carnivores

In several field observations, foxes, Spotted hyaenas and other carnivores killed many more prey individuals than they could eat. Functional and causal aspects of this phenomenon are discussed and the conclusion is reached that these surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmental requirements.  

Summary:

(1) Observations are reported in which carnivores killed considerably more prey animals than they could possibly eat, and causal and functional aspects of this behaviour are discussed. The species concerned were especially foxes and Spotted hyaenas, and references are quoted about surplus killing by other Canidae, Felidae and Ursidae.
(2) It is argued that satiation in carnivores does not inhibit further catching and killing , but it probably does inhibit searching and hunting. Thus carnivores are able to procure an "easy prey" but normally satiation limits numbers killed.
(3) Many, if not all, carnivores possess behaviour patterns which allow utilization of a kill at a later time, or allow other members of the same social unit or offspring to use the food.
(4) Several prey species showed a lack of anti-predator reaction under particular climatological circumstances; it is argued that this lack of response usually has survival value. Sometimes anti-predator behaviour is accidentally made ineffective.
(5) Surplus kills are made possible by (2) and (4) above, and only very rare circumstances give a predator access to so many prey that (3) is ineffective. It is suggested that surplus kills are the consequence of behavioural compromises in both predator and prey to meet opposing environmental requirements.