| genome data on the extinct bison schoetensacki establish it as a sister species of the extant european bison (bison bonasus). | the european bison (bison bonasus), now found in europe and the caucasus, has been proposed to originate either from the extinct steppe/extant american bison lineage or from the extinct bison schoetensacki lineage. bison schoetensacki remains are documented in eurasian middle pleistocene sites, but their presence in upper pleistocene sites has been questioned. despite extensive genetic studies carried out on the steppe and european bison, no remains from the fossil record morphologically identif ... | 2017 | 28187706 |
| ontogenetic relationships between cranium and mandible in coyotes and hyenas. | developing animals must resolve the conflicting demands of survival and growth, ensuring that they can function as infants or juveniles while developing toward their adult form. in the case of the mammalian skull, the cranium and mandible must maintain functional integrity to meet the feeding needs of a juvenile even as the relationship between parts must change to meet the demands imposed on adults. we examine growth and development of the cranium and mandible, using a unique ontogenetic series ... | 2011 | 21484852 |
| ecology and demography of free-roaming domestic dogs in rural villages near serengeti national park in tanzania. | free-roaming dogs (canis lupus familiaris) are of public health and conservation concern because of their potential to transmit diseases, such as rabies, to both people and wildlife. understanding domestic dog population dynamics and how they could potentially be impacted by interventions, such as rabies vaccination, is vital for such disease control efforts. for four years, we measured demographic data on 2,649 free-roaming domestic dogs in four rural villages in tanzania: two villages with and ... | 2016 | 27893866 |
| accuracy of mandibular force profiles for bite force estimation and feeding behavior reconstruction in extant and extinct carnivorans. | mandibular force profiles apply the principles of beam theory to identify mandibular biomechanical properties that reflect the bite force and feeding strategies of extant and extinct predators. while this method uses the external dimensions of the mandibular corpus to determine its biomechanical properties, more accurate results could potentially be obtained by quantifying its internal cortical bone distribution. to test this possibility, mandibular force profiles were calculated using both exte ... | 2016 | 27634400 |
| coprolites as a source of information on the genome and diet of the cave hyena. | we performed high-throughput sequencing of dna from fossilized faeces to evaluate this material as a source of information on the genome and diet of pleistocene carnivores. we analysed coprolites derived from the extinct cave hyena (crocuta crocuta spelaea), and sequenced 90 million dna fragments from two specimens. the dna reads enabled a reconstruction of the cave hyena mitochondrial genome with up to a 158-fold coverage. this genome, and those sequenced from extant spotted (crocuta crocuta) a ... | 2012 | 22456883 |
| low leopard populations in protected areas of maputaland: a consequence of poaching, habitat condition, abundance of prey, and a top predator. | identifying the primary causes affecting population densities and distribution of flagship species are necessary in developing sustainable management strategies for large carnivore conservation. we modeled drivers of spatial density of the common leopard (panthera pardus) using a spatially explicit capture-recapture-bayesian approach to understand their population dynamics in the maputaland conservation unit, south africa. we camera-trapped leopards in four protected areas (pas) of varying sizes ... | 2017 | 28331603 |
| caching reduces kleptoparasitism in a solitary, large felid. | food caching is a common strategy used by a diversity of animals, including carnivores, to store and/or secure food. despite its prevalence, the drivers of caching behaviour, and its impacts on individuals, remain poorly understood, particularly for short-term food cachers. leopards panthera pardus exhibit a unique form of short-term food caching, regularly hoisting, storing and consuming prey in trees. we explored the factors motivating such behaviour among leopards in the sabi sand game reserv ... | 2017 | 28217865 |
| correction: measuring faecal epi-androsterone as an indicator of gonadal activity in spotted hyenas (crocuta crocuta). | [this corrects the article doi: 10.1371/journal.pone.0128706.]. | 2017 | 27662588 |
| landscape-level movement patterns by lions in western serengeti: comparing the influence of inter-specific competitors, habitat attributes and prey availability. | where apex predators move on the landscape influences ecosystem structure and function and is therefore key to effective landscape-level management and species-specific conservation. however the factors underlying predator distribution patterns within functional ecosystems are poorly understood. predator movement should be sensitive to the spatial patterns of inter-specific competitors, spatial variation in prey density, and landscape attributes that increase individual prey vulnerability. we in ... | 2016 | 27375849 |
| spatial patterns of african ungulate aggregation reveal complex but limited risk effects from reintroduced carnivores. | the "landscape of fear" model, recently advanced in research on the non-lethal effects of carnivores on ungulates, predicts that prey will exhibit detectable antipredator behavior not only during risky times (i.e., predators in close proximity) but also in risky places (i.e., habitat where predators kill prey or tend to occur). aggregation is an important antipredator response in numerous ungulate species, making it a useful metric to evaluate the strength and scope of the landscape of fear in a ... | 2016 | 27349090 |
| long-distance communication facilitates cooperation among wild spotted hyaenas, crocuta crocuta. | calls that catalyse group defence, as in the mobbing of predators, appear to facilitate cooperation by recruiting receivers to act collectively. however, even when such signals reliably precede cooperative behaviour, the extent to which the calls function as recruitment signals is unclear. calls might simply arouse listeners' attention, setting off a cascade of independent responses to the threat. by contrast, they might convey information, for example, about signaller identity and the nature of ... | 2015 | 25908882 |
| effects of trophy hunting leftovers on the ranging behaviour of large carnivores: a case study on spotted hyenas. | human-related food resources such as garbage dumps and feeding sites have been shown to significantly influence space use, breeding success and population dynamics in a variety of animal species. in contrast, relatively little is known on the effects of unpredictable sources of food, such as carcasses discarded by hunters, on carnivore species. we evaluated the effect of elephant carcasses, mainly deriving from trophy hunting, on the ranging and feeding behavior of spotted hyenas (crocuta crocut ... | 2015 | 25793976 |
| socioecological variables predict telomere length in wild spotted hyenas. | telomeres are regarded as important biomarkers of ageing and serve as useful tools in revealing how stress acts at the cellular level. however, the effects of social and ecological factors on telomere length remain poorly understood, particularly in free-ranging mammals. here, we investigated the influences of within-group dominance rank and group membership on telomere length in wild adult spotted hyenas (crocuta crocuta). we found large effects of both factors; high-ranking hyenas exhibited si ... | 2015 | 25716089 |
| 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. t ... | 2015 | 25530248 |
| differential effects of temperature change and human impact on european late quaternary mammalian extinctions. | species that inhabited europe during the late quaternary were impacted by temperature changes and early humans, resulting in the disappearance of half of the european large mammals. however, quantifying the relative importance that each factor had in the extinction risk of species has been challenging, mostly due to the spatio-temporal biases of fossil records, which complicate the calibration of realistic and accurate ecological niche modeling. here, we overcome this problem by using ecotypes, ... | 2015 | 25311114 |
| limited social learning of a novel technical problem by spotted hyenas. | social learning can have profound evolutionary consequences because it drives the diffusion of novel behaviours among individuals and promotes the maintenance of traditions within populations. we inquired whether spotted hyenas (crocuta crocuta), generalist carnivores living in complex, primate-like societies, acquire information from conspecifics about a novel problem-solving task. previously, we presented wild hyenas with a food-access puzzle and found that social learning opportunities did no ... | 2014 | 25245305 |
| complex sources of variance in female dominance rank in a nepotistic society. | many mammalian societies are structured by dominance hierarchies, and an individual's position within this hierarchy can influence reproduction, behaviour, physiology and health. in nepotistic hierarchies, which are common in cercopithecine primates and also seen in spotted hyaenas, crocuta crocuta, adult daughters are expected to rank immediately below their mother, and in reverse age order (a phenomenon known as 'youngest ascendancy'). this pattern is well described, but few studies have syste ... | 2014 | 26997663 |
| space use of african wild dogs in relation to other large carnivores. | interaction among species through competition is a principle process structuring ecological communities, affecting behavior, distribution, and ultimately the population dynamics of species. high competition among large african carnivores, associated with extensive diet overlap, manifests in interactions between subordinate african wild dogs (lycaon pictus) and dominant lions (panthera leo) and spotted hyenas (crocuta crocuta). using locations of large carnivores in hluhluwe-imfolozi park, south ... | 2014 | 24896638 |
| development of the external genitalia: perspectives from the spotted hyena (crocuta crocuta). | this review/research paper summarizes data on development of the external genitalia of the spotted hyena, a fascinating mammal noted for extreme masculinization of the female external genitalia. the female spotted hyena is the only extant mammal that mates and gives birth through a pendulous penis-like clitoris. our studies indicate that early formation of the phallus in both males and females is independent of androgens; indeed the phallus forms before the fetal testes or ovaries are capable of ... | 2016 | 24582573 |
| squamous cell carcinoma of the anal sac in a spotted hyena (crocuta crocuta). | a 25-yr-old spayed female spotted hyena (crocuta crocuta) developed intermittent right pelvic limb lameness that persisted following conservative medical therapy. no obvious musculoskeletal lesions were noted on initial physical exam; however, spinal radiography was suspicious for possible intervertebral degenerative joint disease or discospondylitis. despite prolonged medical therapy, the lameness progressed to minimal weight bearing and marked muscle atrophy of the right pelvic limb. electromy ... | 2013 | 24450071 |
| pleistocene chinese cave hyenas and the recent eurasian history of the spotted hyena, crocuta crocuta. | the living hyena species (spotted, brown, striped and aardwolf) are remnants of a formerly diverse group of more than 80 fossil species, which peaked in diversity in the late miocene (about 7-8 ma). the fossil history indicates an african origin, and morphological and ancient dna data have confirmed that living spotted hyenas (crocuta crocuta) of africa were closely related to extinct late pleistocene cave hyenas from europe and asia. the current model used to explain the origins of eurasian cav ... | 2014 | 24320717 |
| two new species of cylicospirura vevers, 1922 (nematoda: spirocercidae) from carnivores in southern africa, with validation of the related genera gastronodus singh, 1934 and skrjabinocercina matschulsky, 1952. | two new species of cylicospirura vevers, 1922 are described from carnivores from southern africa. cylicospirura crocutae junker et mutafchiev sp. n. from crocuta crocuta (erxleben) in zimbabwe is distinguished from its congeners by combinations of characters, including the presence of four cephalic and four external labial papillae, while internal labial papillae were not distinct, the presence of groups of small accessory teeth between the six large tricuspid teeth, the fifth and the sixth pair ... | 2013 | 24261135 |
| complete genome sequence of the crocuta crocuta papillomavirus type 1 (ccrpv1) from a spotted hyena, the first papillomavirus characterized in a member of the hyaenidae. | we report the complete genomic sequence of the crocuta crocuta papillomavirus type 1 (ccrpv1), isolated from an oral papillomatous lesion of a wild spotted hyena. this virus is the first papillomavirus found in a species belonging to the hyaenidae family of carnivores, and it can be classified in the genus lambdapapillomavirus. | 2013 | 23405364 |
| innovative problem solving by wild spotted hyenas. | innovative animals are those able to solve novel problems or invent novel solutions to existing problems. despite the important ecological and evolutionary consequences of innovation, we still know very little about the traits that vary among individuals within a species to make them more or less innovative. here we examine innovative problem solving by spotted hyenas (crocuta crocuta) in their natural habitat, and demonstrate for the first time in a non-human animal that those individuals exhib ... | 2012 | 22874748 |
| sibling rivalry: training effects, emergence of dominance and incomplete control. | within-brood or -litter dominance provides fitness-related benefits if dominant siblings selfishly skew access to food provided by parents in their favour. models of facultative siblicide assume that dominants exert complete control over their subordinate sibling's access to food and that control is maintained, irrespective of the subordinate's hunger level. by contrast, a recent functional hypothesis suggests that subordinates should contest access to food when the cost of not doing so is high. ... | 2012 | 22719032 |
| validation of an enzyme immunoassay for the measurement of faecal glucocorticoid metabolites in spotted hyenas (crocuta crocuta). | the use of enzyme immunoassays (eias) to measure faecal glucocorticoid metabolites (fgcm) is a useful non-invasive technique to monitor adrenocortical activity in vertebrates. the first objective of this study was to validate an 'in-house' eia (cortisol-3-cmo) for the measurement of fgcm concentrations in spotted hyenas. high-performance liquid chromatography (hplc) was used to characterise fgcm in samples from a captive hyena that received an i.v. injection of [(3)h] cortisol. all hplc fraction ... | 2012 | 22634955 |
| adaptability of large carnivores to changing anthropogenic food sources: diet change of spotted hyena (crocuta crocuta) during christian fasting period in northern ethiopia. | | 2012 | 22486435 |
| society, demography and genetic structure in the spotted hyena. | spotted hyenas (crocuta crocuta) are large mammalian carnivores, but their societies, called 'clans', resemble those of such cercopithecine primates as baboons and macaques with respect to their size, hierarchical structure, and frequency of social interaction among both kin and unrelated group-mates. however, in contrast to cercopithecine primates, spotted hyenas regularly hunt antelope and compete with group-mates for access to kills, which are extremely rich food sources, but also rare and ep ... | 2012 | 21880088 |
| variance estimation for systematic designs in spatial surveys. | in spatial surveys for estimating the density of objects in a survey region, systematic designs will generally yield lower variance than random designs. however, estimating the systematic variance is well known to be a difficult problem. existing methods tend to overestimate the variance, so although the variance is genuinely reduced, it is over-reported, and the gain from the more efficient design is lost. the current approaches to estimating a systematic variance for spatial surveys are to app ... | 2011 | 21534940 |
| sex and the frontal cortex: a developmental ct study in the spotted hyena. | the purpose of this study was to examine developmental and individual variation in total endocranial volume and regional brain volumes, including the anterior cerebrum, posterior cerebrum and cerebellum/brain stem, in the spotted hyena (crocuta crocuta). the spotted hyena is a highly gregarious animal noted for living in large, hierarchically organized groups. the social lives of male and female spotted hyenas do not differ until after puberty, when males disperse from the natal group, while fem ... | 2010 | 21088374 |
| endocrine correlates of pregnancy in the ring-tailed lemur (lemur catta): implications for the masculinization of daughters. | female ring-tailed lemurs (lemur catta) are malagasy primates that are size monomorphic with males, socially dominate males, and exhibit a long, pendulous clitoris, channeled by the urethra. these masculine traits evoke certain attributes of female spotted hyenas (crocuta crocuta) and draw attention to the potential role of androgens in lemur sexual differentiation. here, hormonal correlates of prenatal development were assessed to explore the possibility that maternal androgens may shape the ma ... | 2011 | 20932838 |
| what the hyena's laugh tells: sex, age, dominance and individual signature in the giggling call of crocuta crocuta. | among mammals living in social groups, individuals form communication networks where they signal their identity and social status, facilitating social interaction. in spite of its importance for understanding of mammalian societies, the coding of individual-related information in the vocal signals of non-primate mammals has been relatively neglected. the present study focuses on the spotted hyena crocuta crocuta, a social carnivore known for its complex female-dominated society. we investigate i ... | 2010 | 20353550 |
| ontogenetic change in skull morphology and mechanical advantage in the spotted hyena (crocuta crocuta). | weaning represents a challenging transition for young mammals, one particularly difficult for species coping with extreme conditions during feeding. spotted hyenas (crocuta crocuta) experience such extreme conditions imposed by intense feeding competition during which the ability to consume large quantities of food quickly is highly advantageous. as adult spotted hyenas have massive skulls specialized for durophagy and can feed very rapidly, young individuals are likely at a competitive disadvan ... | 2010 | 19862838 |
| post-weaning maternal effects and the evolution of female dominance in the spotted hyena. | mammalian societies in which females dominate males are rare, and the factors favouring the evolution of female dominance have yet to be clearly identified. we propose a new hypothesis for the evolution of female dominance and test its predictions with empirical data from the spotted hyena (crocuta crocuta), a well-studied species characterized by female dominance. we suggest that constraints imposed by the development of a feeding apparatus specialized for bone cracking, in combination with the ... | 2009 | 19324728 |
| chemical characterization of milk oligosaccharides of a spotted hyena (crocuta crocuta). | the carnivora include the superfamilies canoidea and feloidea. in species of canoidea other than canidae, the milk contains only traces of lactose and much larger concentrations of oligosaccharides. in this study, the following oligosaccharides were characterized in the milk of a spotted hyena, which is a species of feloidea species: neu5ac(alpha2-3)gal(beta1-4)glc, gal(alpha1-3)[fuc(alpha1-2)]gal(beta1-4)glc, gal(alpha1-3)gal(beta1-4)glc and fuc(alpha1-2)gal(beta1-4)glc. lactose was found to be ... | 2009 | 18840538 |
| do female hyaenas choose mates based on tenure? | in their investigation into whether female mate-choice drives male dispersal, höner et al. argue that female spotted hyaenas (crocuta crocuta) prefer mates whose tenure in the social group is less than the females' age, to avoid paternal incest, and suggest that male dispersal reflects this preference. however, we are not persuaded that females choose mates on the basis of tenure because höner et al. overlook the alternative hypothesis that dispersal status itself is important in female mate-cho ... | 2008 | 18615020 |
| external genital morphology of the ring-tailed lemur (lemur catta): females are naturally "masculinized". | the extravagance and diversity of external genitalia have been well characterized in male primates; however, much less is known about sex differences or variation in female form. our study represents a departure from traditional investigations of primate reproductive anatomy because we 1) focus on external rather than internal genitalia, 2) measure both male and female structures, and 3) examine a strepsirrhine rather than an anthropoid primate. the subjects for morphological study were 21 repro ... | 2008 | 17972270 |
| diagnosis and treatment of chronic t-lymphocytic leukemia in a spotted hyena (crocuta crocuta). | physical examination of an asymptomatic 20-yr-old intact female spotted hyena (crocuta crocuta) revealed a midabdominal mass. a complete blood count (cbc) revealed peripheral lymphocytosis. abdominal ultrasonography and laparoscopy confirmed severe splenomegaly. cytologic examination of a bone-marrow core and histologic examination of spleen and liver biopsy samples revealed neoplastic small lymphocytes. immunohistochemical staining of liver and spleen samples with the use of leukocyte-specific ... | 2007 | 17939362 |
| non-invasive measurement of fecal estrogens in the spotted hyena (crocuta crocuta). | fecal hormone analysis is a useful tool for frequent, non-invasive sampling of free-living animals. estrogens fluctuate throughout life among reproductive states in female animals, and intensive repetitive sampling can permit accurate assessment of female reproductive condition. this type of repetitive sampling is difficult in large carnivores, including the spotted hyena (crocuta crocuta). patterns of estrogen secretion in captive and free-living hyenas are virtually unknown. here we present va ... | 2008 | 17884046 |
| 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 disper ... | 2007 | 17700698 |
| sex and seasonal differences in aggression and steroid secretion in lemur catta: are socially dominant females hormonally 'masculinized'? | female social dominance characterizes many strepsirrhine primates endemic to madagascar, but currently there is no comprehensive explanation for how or why female lemurs routinely dominate males. reconstructing the evolutionary pressures that may have shaped female dominance depends on better understanding the mechanism of inheritance, variation in trait expression, and correlating variables. indeed, relative to males, many female lemurs also display delayed puberty, size monomorphism, and 'masc ... | 2007 | 17382329 |
| social intelligence in the spotted hyena (crocuta crocuta). | if the large brains and great intelligence characteristic of primates were favoured by selection pressures associated with life in complex societies, then cognitive abilities and nervous systems with primate-like attributes should have evolved convergently in non-primate mammals living in large, elaborate societies in which social dexterity enhances individual fitness. the societies of spotted hyenas are remarkably like those of cercopithecine primates with respect to size, structure and pattern ... | 2007 | 17289649 |
| structure of the midterm placenta of the spotted hyena, crocuta crocuta, with emphasis on the diverse hemophagous regions. | the hyena placenta is unique among carnivores in being hemochorial. it also has areas of erythrocyte uptake that differ from those seen in more commonly studied carnivores. the availability of timed midterm pregnancies made it possible to examine the organization of the placenta, the distribution of regions of columnar trophoblast and the nature of the heterophagous and hemophagous regions in well-preserved material. the labyrinth of the placenta is orderly arranged with periodic primary villi t ... | 2006 | 17108685 |
| mammalian sexual differentiation: lessons from the spotted hyena. | female spotted hyenas (crocuta crocuta) are the only female mammals that lack an external vaginal opening. mating and birth take place through a urogenital canal that exits at the tip of a hypertrophied clitoris. this 'masculine' phenotype spurred a search for an alternate source of fetal androgens. although androstenedione from the maternal ovary is readily metabolized to testosterone by the hyena placenta, formation of the penile clitoris and scrotum appear to be largely androgen independent. ... | 2006 | 17010637 |
| endocrine differentiation of fetal ovaries and testes of the spotted hyena (crocuta crocuta): timing of androgen-independent versus androgen-driven genital development. | female spotted hyenas (crocuta crocuta) have an erectile peniform clitoris and a pseudoscrotum but no external vagina, all established by day 35 of a 110-day gestation. recent studies indicate that these events are androgen-independent, although androgen secretion by fetal ovaries and testis was hypothesized previously to induce phallic development in both sexes. we present the first data relating to the capacity of the ovaries and testes of the spotted hyena to synthesize androgens at different ... | 2006 | 17008476 |
| rank-related maternal effects of androgens on behaviour in wild spotted hyaenas. | within any hierarchical society, an individual's social rank can have profound effects on its health and reproductive success, and rank-related variation in these traits is often mediated by variation in endocrine function. maternal effects mediated by prenatal hormone exposure are potentially important for non-genetic inheritance of phenotypic traits related to social rank, and thus for shaping individual variation in behaviour and social structure. here we show that androgen concentrations in ... | 2006 | 16641996 |
| the ontogeny of the urogenital system of the spotted hyena (crocuta crocuta erxleben). | studies were conducted to elucidate the importance of androgen-mediated induction of the extreme masculinization of the external genitalia in female spotted hyenas. phallic size and shape; androgen receptor (ar) and alpha-actin expression; and sex-specific differences in phallic retractor musculature, erectile tissue, tunica albuginea, and urethra/urogenital sinus were examined in male and female fetuses from day 30 of gestation to term. similar outcomes were assessed in fetuses from dams treate ... | 2005 | 15917348 |
| non-invasive monitoring of fecal androgens in spotted hyenas (crocuta crocuta). | spotted hyenas (crocuta crocuta) exhibit an array of behavioral and morphological characteristics that set them apart from other mammals: females are heavier and more aggressive than males, and females have external genitalia that closely resemble those of the male. because androgenic hormones might mediate the expression of these traits, androgens are of great interest in this species. past work on circulating androgens in wild hyenas has been limited, in part because of small sample sizes. in ... | 2004 | 14644644 |
| effects of dispersal status on pituitary and gonadal function in the male spotted hyena. | male spotted hyenas (crocuta crocuta) reach puberty at 24 months of age and then usually emigrate from their natal clans one to 52 months later. recent work has shown that reproductive success is very low among adult males still residing in their natal groups, and it is similarly low among recent or "short-term" immigrants. long-term immigrants father the vast majority of cubs born. here we inquired whether these differences in reproductive success might be associated with variation among males ... | 2003 | 14644632 |
| topography of photoreceptors and retinal ganglion cells in the spotted hyena (crocuta crocuta). | the spatial distributions of photoreceptors and retinal ganglion cells were examined in the spotted hyena (crocuta crocuta). two populations of cones were identified by immunocytochemical labeling. the hyena retina contains approximately 2.3 million middle- to long-wavelength sensitive (m/l) cones that reach peak densities of about 7,500/mm(2) in the vicinity of the optic nerve head. a sparser population of short-wavelength sensitive (s) cones, totaling about 0.3 million, was also detected. ther ... | 2003 | 14573992 |
| 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 ... | 2003 | 12816637 |
| urogenital system of the spotted hyena (crocuta crocuta erxleben): a functional histological study. | the unique urogenital anatomy and histology of female spotted hyenas (crocuta crocuta erxleben) was reexamined to identify adaptations of "structure" that enable/facilitate urination, mating, and parturition through the clitoris. unusual features of penile anatomy required for meeting ceremonies and successful mating through a clitoral point of insertion were also examined. as reported previously, the upper urogenital tract of the female spotted hyena is typical of other carnivores and consists ... | 2003 | 12635111 |
| responses to olfactory stimuli in spotted hyenas (crocuta crocuta): ii. discrimination of conspecific scent. | scent marking in spotted hyenas (crocuta crocuta) includes the deposition of anal sac secretions, or "paste," and presumably advertises territorial ownership. to test whether captive hyenas classify and discriminate individuals using odor cues in paste, the authors conducted behavioral discrimination bioassays and recorded hyena investigation of paste extracted from various conspecific donors. in experiment 1, subjects directed most investigative behavior toward scents from unfamiliar hyenas and ... | 2002 | 12539929 |
| responses to olfactory stimuli in spotted hyenas (crocuta crocuta): i. investigation of environmental odors and the function of rolling. | olfaction is crucial to spotted hyenas (crocuta crocuta), yet there are no controlled studies of their reactions to odors. in experiment 1, the authors examined responses of captive hyenas to various environmental (prey, nonprey animal, and plant) odors. subjects approached and sniffed all odors equally but preferentially licked prey odors, scent marked next to odors, and rolled in animal-based odors. in experiment 2, the authors examined the function of rolling by applying odors to the pelts of ... | 2002 | 12539928 |
| exposure to naturally circulating androgens during foetal life incurs direct reproductive costs in female spotted hyenas, but is prerequisite for male mating. | among all extant mammals, only the female spotted hyena (crocuta crocuta) mates and gives birth through the tip of a peniform clitoris. clitoral morphology is modulated by foetal exposure to endogenous, maternal androgens. first births through this organ are prolonged and remarkably difficult, often causing death in neonates. additionally, mating poses a mechanical challenge for males, as they must reach an anterior position on the female's abdomen and then achieve entry at the site of the retra ... | 2002 | 12396496 |
| effects of prenatal treatment with antiandrogens on luteinizing hormone secretion and sex steroid concentrations in adult spotted hyenas, crocuta crocuta. | prenatal androgen treatment can alter lh secretion in female offspring, often with adverse effects on ovulatory function. however, female spotted hyenas (crocuta crocuta), renowned for their highly masculinized genitalia, are naturally exposed to high androgen levels in utero. to determine whether lh secretion in spotted hyenas is affected by prenatal androgens, we treated pregnant hyenas with antiandrogens (flutamide and finasteride). later, adult offspring of the antiandrogen-treated (aa) moth ... | 2002 | 12390869 |
| ultrasonic measurements of second and third trimester fetuses to predict gestational age and date of parturition in captive and wild spotted hyenas crocuta crocuta. | parturition in spotted hyenas (crocuta crocuta) is a fascinating event to witness, as females of this species are highly masculinized and give birth through a penis-like clitoris. furthermore, shortly after birth, a high rate of aggression occurs between littermates that can sometimes end in siblicide. to study these events thoroughly, an accurate estimate of the date of parturition is necessary. to this end, we performed transabdominal ultrasounds every 20-30 days in five captive spotted hyenas ... | 2002 | 12212886 |
| transient masculinization in the fossa, cryptoprocta ferox (carnivora, viverridae). | in at least 9 mammalian species, females are masculinized throughout life, but the benefits of this remain unclear despite decades of thorough study, in particular of the spotted hyaena (crocuta crocuta) in which the phenomenon has been associated with a high fitness cost. through examination of wild and captive fossas (cryptoprocta ferox, viverridae), androgen assays, and dna typing for confirmation of gender, we made the first discovery of transient masculinization of a female mammal. juvenile ... | 2002 | 11870065 |
| androgens and the role of female "hyperaggressiveness" in spotted hyenas (crocuta crocuta). | it has been suggested that female dominance in spotted hyenas evolved due to selection for "hyperaggressive" androgenized females. according to this view, virilized external genitalia of female hyenas developed as a byproduct of selection for "androgen-facilitated social dominance." the evidence that female hyenas have higher androgen levels than males or other female mammals is inconclusive. we compared concentrations of testosterone (t), 5alpha-dihydrotestosterone (dht), and androstenedione (a ... | 2001 | 11161886 |
| 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 ... | 2000 | 11007641 |
| microsatellite loci in the spotted hyena crocuta crocuta. | | 2000 | 10972789 |
| within-litter sibling aggression in spotted hyaenas: effect of maternal nursing, sex and age. | models that address facultative siblicide in avian species predict that the costs and benefits of sibling aggression will change in relation to the level of food provisioning by parents. in spotted hyaenas, crocuta crocuta, one of the few mammalian species in which facultative siblicide occurs, aggression rates between siblings were highest when cubs competed for access to maternal milk. in the serengeti national park, tanzania, nursing of cubs by spotted hyaena mothers was influenced by the mig ... | 1999 | 10512644 |
| siblicide revisited in the spotted hyaena: does it conform to obligate or facultative models? | aggression among spotted hyaena, crocuta crocuta, siblings is often intense, and sometimes lethal. frank et al. (1991, science, 252, 702-704) proposed that siblicide routinely occurs in half of all spotted hyaena litters, namely those composed of same-sex twins. we propose an alternative to this 'obligate' model. in our 'facultative' model we suggest that siblicide is far less common than previously supposed, and that it occurs only when resources are insufficient to sustain two cubs. according ... | 1999 | 10479370 |
| 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 ... | 1999 | 10505059 |
| noninvasive fecal monitoring of glucocorticoids in spotted hyenas, crocuta crocuta. | the aim of this study was to validate a method for measuring glucocorticoids noninvasively in feces of spotted hyenas (crocuta crocuta). three established enzyme immunoassays (eia) for cortisol, corticosterone, and 11-oxoetiocholanolone were tested, but proved unsatisfactory. a new eia using another corticosterone antibody was established and was used for all subsequent analyses; this eia was validated by demonstrating parallelism between serial dilutions of spotted hyena fecal extracts and dilu ... | 1999 | 10336822 |
| androgens and masculinization of genitalia in the spotted hyaena (crocuta crocuta). 3. effects of juvenile gonadectomy. | studies involving the administration of anti-androgens to spotted hyaenas during fetal development have raised questions concerning the precise contributions of steroids to phallic growth in these animals. if gonadal androgens promote postnatal penile growth in males, the following would be expected: (a) a period of accelerated growth accompanying achievement of puberty, and (b) a marked reduction in adult penile size and density of penile spines after gonadectomy. if a similar androgenic pubert ... | 1998 | 9713385 |
| androgens and masculinization of genitalia in the spotted hyaena (crocuta crocuta). 2. effects of prenatal anti-androgens. | pregnant spotted hyaenas were treated with anti-androgens to interfere with the unusually masculine 'phallic' development that characterizes females of this species. the effects on genital morphology and plasma androgen concentrations of infants were studied during the first 6 months of life. although there were consistent 'feminizing' effects of prenatal anti-androgen treatment on genital morphology in both sexes, such exposure did not produce males with extreme hypospadia, as it does in other ... | 1998 | 9713384 |
| dispersal status influences hormones and behavior in the male spotted hyena. | male spotted hyenas (crocuta crocuta) reach puberty at 24 months of age and then invariably emigrate from their natal clans 1 to 38 months later. thus there are two classes of reproductively mature males in every crocuta clan: adult natal males born in the clan and adult immigrant males born elsewhere. in one free-living hyena population in kenya, these two groups of males were compared with respect to measures of aggression, social dominance, sexual behavior, and circulating hormone levels. adu ... | 1998 | 9698503 |
| pattern and source of secretion of relaxin in the reproductive cycle of the spotted hyena (crocuta crocuta). | female spotted hyenas are highly masculinized at birth and have no external vagina. copulation with males and birth of young are accomplished through the central urogenital canal of the clitoris. this unusual adaptation requires remarkable changes in the elasticity of the connective tissues of the clitoris, without which neither copulation nor birth would be possible. we hypothesized that relaxin, a hormone that increases the extensibility of the connective tissues of the uterus and cervix of ma ... | 1997 | 9160731 |
| the emergence of affiliative behavior in infant spotted hyenas (crocuta crocuta). | | 1997 | 9071381 |
| frank a. beach award. male-female dominance relations at three ontogenetic stages in the spotted hyena (crocuta crocuta). | | 1995 | 7557917 |
| sex-specific androgen binding in spotted hyaena (crocuta crocuta) plasma. | 1. a charcoal adsorption assay demonstrated a large variance in androgen binding ability in female spotted hyaenas. 2. a positive correlation between plasma androgen binding ability and ovarian steroid concentrations was demonstrated in adult females. 3. the strong plasma binding affinity for testosterone and dihydrotestosterone (dht) (nm) together with the lack of cortisol and weaker oestradiol-17 beta binding suggests that a specific androgen binding substance, possibly a protein, is present i ... | 1992 | 1359953 |
| adrenocortical responsiveness to immobilization stress in spotted hyenas (crocuta crocuta). | 1. the adrenocortical responsiveness to an induced stressor was monitored in free-living spotted hyenas belonging to a number of social and reproductive categories. 2. no significant differences between sexes, or changes in mean cortisol concentrations during serial sampling within the sexes, could be demonstrated. 3. the extreme individual variance in temporal cortisol profiles recorded in this study is inexplicable, as it was not related to differences in immobilization procedure, sex, age, re ... | 1992 | 1356702 |
| a multivariate approach to socio-ecological development and endocrine variance in the spotted hyaena, crocuta crocuta erxleben. | this investigation of the socio-ecological development and endocrine variance in the spotted hyaena, crocuta crocuta, illustrates that the complexity of a multivariate endocrine system cannot fully be understood using the concept of a class mean (mu). any comprehensive investigation of a multivariate endocrine system should also include an analysis of variance (sigma), as it may provide additional insights into the dynamics of an endocrine hypervolume. mean cortisol concentrations could not diff ... | 1992 | 1516685 |
| 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 ... | 1992 | 1404093 |
| hormonal correlates of 'masculinization' in female spotted hyaenas (crocuta crocuta). 2. maternal and fetal steroids. | concentrations of androgens (androstenedione, testosterone, 5 alpha-dihydrotestosterone), oestrogen and progesterone were measured in relation to pregnancy in the spotted hyaena (crocuta crocuta). the gestation period was estimated to be about 110 days. there was a marked progressive rise in all the steroids starting in the first third of gestation. chromatographic separation of plasma showed that much of the oestrogen is not oestradiol (only 12% of total measured) and that a significant fractio ... | 1992 | 1518002 |
| hormonal correlates of 'masculinization' in female spotted hyaenas (crocuta crocuta). 1. infancy to sexual maturity. | this report is concerned with hormone concentrations accompanying sexual maturation in a highly 'masculinized' female mammal, the spotted hyaena, crocuta crocuta. plasma concentrations of testosterone, androstenedione and oestrogen were determined by radioimmunoassay in a longitudinal study of 12 female and eight male hyaenas 2.5-62.5 months old. concentrations of testosterone were significantly higher in males than in females after 26.5 months of age, but earlier measurements did not differ bet ... | 1992 | 1518001 |
| plasma androgens in spotted hyaenas (crocuta crocuta): influence of social and reproductive development. | differences in plasma testosterone and androstenedione concentrations in male spotted hyaenas belonging to various reproductive and social categories 4 clans resident in south africa and botswana suggest that central-immigrant males have the highest concentrations of androgens, reflecting their roles as mating males. social inhibition of reproductive function may occur in other males. a reversal in the ratio of testosterone: androstenedione occurs at puberty in most individuals, testosterone bec ... | 1991 | 1920290 |
| social feeding reverses learned flavor aversions in spotted hyenas (crocuta crocuta). | spotted hyenas are highly social carnivores with competitive feeding habits. it was hypothesized that social feeding might be capable of reversing an established flavor aversion. the dominant hyena of each of 4 captive social groups was given a novel food mixed with licl on day 1; aversion to this food was demonstrated on day 2. on day 3, the dominant hyena and 3 or 4 members of her group were offered the food simultaneously. three of the 4 dominant hyenas ate substantial quantities of the food ... | 1991 | 1650305 |
| sex differences in the play behavior of immature spotted hyenas, crocuta crocuta. | social, locomotor, and object play were studied in a colony of five male and five female peer-reared spotted hyenas during 12 1-hr tests while the animals were 13-19 months of age. animals were tested in both same-sex and mixed-sex groups and were stimulated to play by the introduction of fresh straw and sawdust bedding. each test was videotaped and the frequency of each type of play was determined by a time sampling procedure. females played more frequently than males, however, the category of ... | 1990 | 2227852 |
| descriptive and functional morphology of the locomotory apparatus of the spotted hyaena (crocuta crocuta, erxleben, 1777). | the musculature of the limbs, neck and back of crocuta crocuta is described and some functional aspects are discussed. the myology of c. crocuta generally corresponds with that of h. hyaena. both species show adaptations to lifting and carrying heavy loads, but the larger size and more robust morphology of c. crocuta enables it to master larger prey than h. hyaena. a remarkable over-extension of the tarsus in c. crocuta is described which was observed both in the cadaver and in vivo, during the ... | 1989 | 2764282 |
| androstenedione may organize or activate sex-reversed traits in female spotted hyenas. | spotted hyenas (crocuta crocuta erxleben) present a unique syndrome of reversal in behavioral and anatomical distinction between the sexes: females are heavier and more aggressive than males and dominant over them. the female's external genitalia include a false scrotum and a fully erectile pseudopenis through which mating and birth take place. results of studies of circulating testosterone levels in wild spotted hyenas do not account for the "male-like" characteristics of the female. androstene ... | 1987 | 3472215 |
| adrenal and gonadal contribution to circulating androgens in spotted hyaenas (crocuta crocuta) as revealed by lhrh, hcg and acth stimulation. | single venous blood samples were collected from 52 hyaenas and serial samples via indwelling jugular catheters from 8 hyaenas. social status of the hyaenas was unknown. radioimmunoassay estimations were specific for testosterone, androstenedione, cortisol and lh. no significant differences could be found between the sexes for concentrations of testosterone (adult males 2.9 +/- 1.3 nmol/l; adult females (non-pregnant) 1.6 +/- 0.3 nmol/l). androstenedione concentrations in sub-adult males were sig ... | 1986 | 3020243 |
| lymphosarcoma in a spotted hyena, crocuta crocuta. | lymphosarcoma of the mesenteric and mediastinal lymph nodes with peritoneal and mediastinal implantations, as well as widespread intravascular metastases and thrombosis with haemorrhages was diagnosed in a spotted hyena. | 1983 | 6689181 |
| the chorioallantoic placenta of the spotted hyena (crocuta crocuta erxleben): an electron microscopic study. | the histology and ultrastructure of the chorioallantoic placenta of the spotted hyena have been studied in three specimens obtained in the field and fixed promptly with glutaraldehyde. observations revealed that the interhemal membrane at its minimal thickness is hemomonochorial, consisting of a continuous layer of syncytial trophoblast, a basal lamina, and fetal capillary endothelium. cytotrophoblastic cells form a discontinuous layer beneath the syncytial trophoblast and are distinguished by t ... | 1982 | 7158827 |
| fetal androgens and sexual mimicry in spotted hyaenas (crocuta crocuta). | sexual differentiation of the müllerian duct system and gonad in female fetuses conformed to the general mammalian pattern, whereas the external genital anlage in male and female fetuses developed into the male facies. interstitial cells occurred in the primary germinal cords of both male and female fetal gonads and are suggested to be the source of androgen production in spotted hyaena fetuses. maternal transfer of androgens to the fetus via the placenta was negligible. male fetuses had higher ... | 1982 | 7097645 |
| sexual dimorphism of the phallus in spotted hyaena (crocuta crocuta). | the weight of the skinned phallus and the diameter of its shaft and glans did not differ significantly in the two sexes of spotted hyaena, but phallus length was greater in males. the urethra of the penis was surrounded by corpus spongiosum, while the urogenital canal of the clitoris was suspended beneath the erectile bodies in loose connective tissue, an arrangement compatible with dilatation of the canal during copulation and parturition. the average width of the phallic meatus in juvenile fem ... | 1980 | 7431309 |
| placentation in the spotted hyena (crocuta crocuta erxleben), with particular reference to the circulation. | | 1964 | 14210298 |
| placentation in the spotted hyena (crocuta crocuta erxleben). | | 1957 | 13448996 |
| [cysticercosis of the sacrum bone of antelopes and taenia olngojinei sp. nov. of the spotted hyena]. | | 1969 | 5393200 |
| 'neanderthal bone flutes': simply products of ice age spotted hyena scavenging activities on cave bear cubs in european cave bear dens. | punctured extinct cave bear femora were misidentified in southeastern europe (hungary/slovenia) as 'palaeolithic bone flutes' and the 'oldest neanderthal instruments'. these are not instruments, nor human made, but products of the most important cave bear scavengers of europe, hyenas. late middle to late pleistocene (mousterian to gravettian) ice age spotted hyenas of europe occupied mainly cave entrances as dens (communal/cub raising den types), but went deeper for scavenging into cave bear den ... | 2015 | 26064624 |
| cross-species transmission of canine distemper virus-an update. | canine distemper virus (cdv) is a pantropic morbillivirus with a worldwide distribution, which causes fatal disease in dogs. affected animals develop dyspnea, diarrhea, neurological signs and profound immunosuppression. systemic cdv infection, resembling distemper in domestic dogs, can be found also in wild canids (e.g. wolves, foxes), procyonids (e.g. raccoons, kinkajous), ailurids (e.g. red pandas), ursids (e.g. black bears, giant pandas), mustelids (e.g. ferrets, minks), viverrids (e.g. civet ... | 2015 | 28616465 |
| the relationship between direct predation and antipredator responses: a test with multiple predators and multiple prey. | most species adjust their behavior to reduce the likelihood of predation. many experiments have shown that antipredator responses carry energetic costs that can affect growth, survival, and reproduction, so that the total cost of predation depends on a trade-off between direct predation and risk effects. despite these patterns, few field studies have examined the relationship between direct predation and the strength of antipredator responses, particularly for complete guilds of predators and pr ... | 2017 | 28475209 |
| simplified large african carnivore density estimators from track indices. | the range, population size and trend of large carnivores are important parameters to assess their status globally and to plan conservation strategies. one can use linear models to assess population size and trends of large carnivores from track-based surveys on suitable substrates. the conventional approach of a linear model with intercept may not intercept at zero, but may fit the data better than linear model through the origin. we assess whether a linear regression through the origin is more ... | 2016 | 28028454 |
| fear of the dark or dinner by moonlight? reduced temporal partitioning among africa's large carnivores. | africa is home to the last intact guild of large carnivores and thus provides the only opportunity to investigate mechanisms of coexistence among large predator species. strong asymmetric dominance hierarchies typically characterize guilds of large carnivores; but despite this asymmetry, subdominant species may persist alongside their stronger counterparts through temporal partitioning of habitat and resources. in the african guild, the subdominant african wild dogs and cheetahs are routinely de ... | 2012 | 23431590 |
| molecular characterization of canine kobuvirus in wild carnivores and the domestic dog in africa. | knowledge of kobuvirus (family picornaviridae) infection in carnivores is limited and has not been described in domestic or wild carnivores in africa. to fill this gap in knowledge we used rt-pcr to screen fresh feces from several african carnivores. we detected kobuvirus rna in samples from domestic dog, golden jackal, side-striped jackal and spotted hyena. using next generation sequencing we obtained one complete kobuvirus genome sequence from each of these species. our phylogenetic analyses r ... | 2015 | 25667111 |
| the intestinal eukaryotic and bacterial biome of spotted hyenas: the impact of social status and age on diversity and composition. | in mammals, two factors likely to affect the diversity and composition of intestinal bacteria (bacterial microbiome) and eukaryotes (eukaryome) are social status and age. in species in which social status determines access to resources, socially dominant animals maintain better immune processes and health status than subordinates. as high species diversity is an index of ecosystem health, the intestinal biome of healthier, socially dominant animals should be more diverse than those of subordinat ... | 2017 | 28670573 |
| measuring fecal testosterone metabolites in spotted hyenas: choosing the wrong assay may lead to erroneous results. | enzyme-immunoassays (eia) that detect fecal testosterone metabolites (ftm) are powerful tools to monitor gonadal activity non-invasively. however, a challenge with testosterone eias might be their potential for cross-reactivities with structurally similar glucocorticoid metabolites. therefore, we aimed to verify the capability of four different testosterone eias to monitor ftm without reflecting changes in adrenocortical activity in spotted hyenas by analyzing fecal samples following testosteron ... | 2017 | 27854157 |
| socioecological predictors of immune defences in wild spotted hyenas. | social rank can profoundly affect many aspects of mammalian reproduction and stress physiology, but little is known about how immune function is affected by rank and other socio-ecological factors in free-living animals.in this study we examine the effects of sex, social rank, and reproductive status on immune function in long-lived carnivores that are routinely exposed to a plethora of pathogens, yet rarely show signs of disease.here we show that two types of immune defenses, complement-mediate ... | 2016 | 27833242 |
| lions as bone accumulators? paleontological and ecological implications of a modern bone assemblage from olduvai gorge. | analytic models have been developed to reconstruct early hominin behaviour, especially their subsistence patterns, revealed mainly through taphonomic analyses of archaeofaunal assemblages. taphonomic research is used to discern which agents (carnivores, humans or both) generate the bone assemblages recovered at archaeological sites. taphonomic frameworks developed during the last decades show that the only large-sized carnivores in african biomes able to create bone assemblages are leopards and ... | 2016 | 27144649 |