Publications

placentation in the spotted hyena (crocuta crocuta erxleben).		1957	13448996
placentation in the spotted hyena (crocuta crocuta erxleben), with particular reference to the circulation.		1964	14210298
trichinosis in a spotted hyaena (crocuta crocuta) of the serengeti.		1966	5948801
[cysticercosis of the sacrum bone of antelopes and taenia olngojinei sp. nov. of the spotted hyena].		1969	5393200
echinococcosis (hydatodosis) in wild animals of the kruger national park.	echinococcosis has been diagnosed in the following wild species in the kruger national park : lion, panthera leo, spotted hyena, crocuta crocuta, cape hunting dog, lycaon pictus, burchell's zebra, equus burchelli antiquorum, buffalo, syncerus caffer, hippopotamus, hippopotamus amphibius, and impala, aepyceros melampus. infestation rates in the herbivores vary from 60% in zebra to less than 1% in impala. species like elephant, loxodonta africana, and blue wildebeest, connochaetes taurinus, do not ...	1975	1219111
identification by the blood incubation infectivity test of trypanosoma brucei subspecies isolated from game animals in the luangwa valley, zambia.	a total of 7 stocks of trypanosoma brucei subspecies, isolated from naturally infected game animals in the luangwa valley, eastern province, zambia were examined using a modified version of the blood incubation infectivity test (biit). one stock giving consistent biit responses typical of t.b. rhodesiense, was obtained from warthog (phacochoerus aethiopicus). four other stocks, 2 from hyaena (crocuta crocuta), 1 from a waterbuck (kobus ellipsiprymnus) and 1 from a lion (panthera leo) responded l ...	1979	44098
[ancylostoma duodenale (dubini, 1843) creplin, 1843 (nematoda: ancylostomidae), parasite of the spotted hyena crocuta crocuta (erxleben) in ethiopia].		1979	554273
the birth and survival of wildebeest calves.	this paper describes social organization, parturition, post partum behavior of wildebeest mothers and offspring, and calf predation during the annual birth peak in ngorongoro crater, tanzania. the wildebeest's "follower-calf" system, unique among the bovidae, is remarkably effective in protecting neonates. even during hte one-month peak, the major predator on calves, the spotted hyena, is unable to feed to satiation. calf survival is consistently high, despite large fluctuations in the numbers o ...	1979	494841
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
free-living jackals (canis mesomelas)-potential reservoir hosts for ehrlichia canis in kenya.	using a modified cell culture test, ehrlichia canis was found in eight of 15 free-living jackals (canis mesomelas) and 14 of 31 dogs owned by pastoral communities in the same areas of kenya. two cross-bred puppies inoculated with blood from infected jackals developed mild, transient clinical disease, and e. canis was recovered from the puppies. tick species found on the jackals were similar to those found on the infected dogs. ehrlichia canis was not found in eight spotted hyaenas (crocuta crocu ...	1980	7463598
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
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
hydatid disease in the turkana district of kenya. iii. the significance of wild animals in the transmission of echinococcus granulosus, with particular reference to turkana and masailand in kenya.	the results are given of a study on the role of wildlife in the transmission of echinococcus granulosus in the turkana and narok districts of kenya. a total of 76 wild carnivores belonging to three separate species was examined from turkana district. echinococcus adults were found in 11 of 38 silver-backed jackals (canis mesomelas) and in six of 22 golden jackals (canis aureus). this is the first record of golden jackals being infected with this parasite in kenya. none of 16 spotted hyaenas (cro ...	1983	6882057
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
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
parasites of domestic and wild animals in south africa. xxii. ixodid ticks on domestic dogs and on wild carnivores.	ixodid ticks were collected from 4 dogs on smallholdings near grahamstown, eastern cape province, on 1 or more occasions each week for periods ranging from 9-36 months. fourteen tick species were recovered and the seasonal abundance of adult haemaphysalis leachi and adult rhipicephalus simus was determined. complete collections of ticks were made from 50 caracals (felis caracal) in the cradock, graaff-reinet and southwell regions in the eastern cape province. the animals from cradock and graaff- ...	1987	3444612
carnivora: primary structure of the hemoglobin from the spotted hyena (crocuta crocuta, hyenidae).	the primary structure of the alpha- and beta-chains of hemoglobin from spotted hyena (crocuta crocuta, hyenidae) is presented. the structure-function relationship is discussed. the separation of the chains directly from hemoglobin was performed by rp-hplc. after tryptic digestion of the chains, the peptides were isolated by rp-hplc. amino-acid sequences were determined by edman degradation in liquid- and gas-phase sequencers. the alignment of the tryptic peptides was made by homology with human ...	1989	2742752
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
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
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
fatal sibling aggression, precocial development, and androgens in neonatal spotted hyenas.	fatal neonatal sibling aggression is common in predatory birds but has not been previously reported in wild mammals. spotted hyena females are strongly masculinized, both anatomically and behaviorally, apparently by high levels of androgens during ontogeny. neonates display elevated androgen levels, precocial motor development, and fully erupted front teeth. litters are usually twins, and siblings fight violently at birth, apparently leading to the death of one sibling in same-sex litters, where ...	1991	2024122
scent marking (pasting) in a colony of immature spotted hyenas (crocuta crocuta): a developmental study.	pasting, a stereotypic form of anal gland scent marking, was studied in 2 cohorts (n = 20) of captive spotted hyenas (crocuta crocuta). a significant increment in the frequency of pasting occurred in both cohorts as the animals approached sexual maturity; however, gonadectomy during the early juvenile age period had no significant effects on subsequent pasting frequency. dominant hyenas in both cohorts tended to scent-mark more frequently than subordinates during the late subadult period. pastin ...	1991	2032450
the primary structure of the hemoglobin from the aardwolf (proteles cristatus, hyaenidae).	the hemoglobin of the aardwolf (proteles cristatus) contains only one component. in this paper, we are presenting its primary structure. the globin chains were separated by high-performance liquid chromatography and the sequences determined by automatic liquid and gas-phase edman degradation of the chains and their tryptic peptides. the alpha- as well as the beta-chains show 20 exchanges compared with the corresponding human chains. the difference to the masked palm civet (paguma larvata) and th ...	1991	1910578
sexual differentiation of the female spotted hyena. one of nature's experiments.		1992	1456636
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
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
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
rabies in the masai mara, kenya: preliminary report.	a serosurvey of rabies antibodies among domestic dogs (canis familiaris, n = 178), spotted hyaenas (crocuta crocuta, n = 72) and african wild dogs (lycaon pictus, n = 18) of the masai mara, kenya, was carried out. rabies antibodies were found in 9.6% of the domestic dog sera, but all wild dog and hyaena sera were negative. rabies has been confirmed in this region among the above species as well as in a domestic cat (felis catus) and a cow (bos indicus) by fluorescent antibody tests (fat) and/or ...	1993	7777329
social systems and behaviour of the african wild dog lycaon pictus and the spotted hyaena crocuta crocuta with special reference to rabies.	differences in the social systems and behaviour of two potentially important hosts of rabies, the african wild dog and the spotted hyaena, may lead to differences in the epizootiology of the disease in the two species. wild dogs are highly social animals in which pack members are in constant physical contact with each other, but in which inter-pack interactions are rare. spotted hyaenas are more flexible in their social systems and behaviour. clan members interact less frequently than do wild do ...	1993	7777328
a mechanism for virilization of female spotted hyenas in utero.	female spotted hyenas exhibit male-like genitalia and dominance over males. hyena ovarian tissues incubated in vitro produced large quantities of the steroid hormone precursor androstenedione. the activity of aromatase, which converts androstenedione to estrogen, was one-twentieth as great in hyena versus human placental homogenates. in comparison, the activity of 17 beta-hydroxysteroid dehydrogenase, which converts androstenedione to testosterone, was equal in the two homogenates. the limited a ...	1993	8391165
sex determination in spotted hyena (crocuta crocuta ) by restriction fragment length polymorphism of amplified zfx/zfy loci.	we describe a quick and efficient method of determining the sex of dna samples in the hyena. by choosing primers from sequences that are conserved between the human and bovine zfy and zfx genes, we amplified a 448 bp fragment from 1 male and 2 female hyenas. using comparative sequencing, single base pair polymorphisms between the amplified zfy and zfx were established. restriction fragment length polymorphism (rflp) analysis with psti and taqi confirmed the sequence data and yielded specific ban ...	1994	16727412
ancylostoma genettae, a. protelesis, a. somaliense: three new species from wild carnivora in the somali republic.	ancylostoma braziliense was found in somalia in acinonyx jubatus, canis familiaris, c. mesomelas, crocuta crocuta, felis catus, f. libyca, genetta genetta, otocyon megalotis, proteles cristatus; a. caninum in a. jubatus, c. familiaris, c. mesomelas, c. crocuta; a. duodenale in c. crocuta; a. iperodontatum in lynx caracal; a. paraduodenale in felis serval; a. tubaeforme in a. jubatus, f. catus, f. libyca; arthrocephalus gambiense in ichneumia albicauda; uncinaria parvibursata in mellivora capensi ...	1995	8778662
frank a. beach award. male-female dominance relations at three ontogenetic stages in the spotted hyena (crocuta crocuta).		1995	7557917
sexual dimorphism of perineal muscles and motoneurons in spotted hyenas.	female spotted hyenas are known for their male-like genitalia, high levels of aggression, and dominance over males, characteristics which are attributed to exposure to elevated levels of testosterone in utero. although the nervous system of spotted hyenas has not previously been examined, one might predict that neural systems which are sexually dimorphic in other mammals would be monomorphic in this species. spinal motoneurons which innervate muscles associated with the phallus are located in on ...	1996	8915834
rank and reproduction in the female spotted hyaena.	female reproductive success varies with social rank in many gregarious mammals, including primates, ungulates and carnivores. social groups of spotted hyaenas (crocuta crocuta) are structured by hierarchical dominance relationships that determine individuals' priority of access to food and other resources. the influence of female social rank on several measures of reproductive success was examined in a population of free-living crocuta in kenya. the study population was continuously observed for ...	1996	9038781
canine distemper virus infection in serengeti spotted hyenas.	clinical signs suggestive of canine distemper virus (cdv) infection were observed among a group of spotted hyenas (crocuta crocuta) in the serengeti, tanzania. virus antigen was detected immunohistologically in a brain sample from a diseased cub. the presence of virus rna could be demonstrated in this brain as well as in intestine and lymph node of the animal by rt-pcr. sequence comparison of brain-derived amplicons showed that the virus was related to recent cdv field isolates. the closest homo ...	1996	8861651
aspects of rabies epidemiology in tsumkwe district, namibia.	aspects of rabies epidemiology were investigated in the tsumkwe district, namibia, during december 1993 and january 1994. a cross-sectional seroepidemiological survey for rabies antibodies was carried out in domestic (n = 70) and wild dogs [lycaon pictus (n = 6)]. an overall seroprevalence rate of 30% was found in domestic dogs, but it must be borne in mind that seroconversion can result from infections from either rabies or rabies-related viruses. older dogs were more likely to be seropositive ...	1997	9204502
demonstration of helicobacter pylori-like organisms in the gastric mucosa of captive exotic carnivores.	samples of gastric tissue from the cardiac, fundic and pyloric region of 30 carnivores comprising 12 tigers (panthera tigris), 10 lions (panthera leo), three pumas (felis concolor), two leopards (panthera pardus), one serval (felis serval), one wolf (canis lupus) and one hyena (crocuta crocuta) kept at german zoological gardens were subjected to histopathological and immunohistochemical examination. selected tissue specimens of 12 animals were examined also by electron microscopy. the purpose of ...	1997	9076597
trichinella nelsoni in carnivores from the serengeti ecosystem, tanzania.	a survey of trichinellosis among sylvatic carnivore mammals from the serengeti ecosystem (tanzania) demonstrated the presence of trichinella nelsoni in 5 of 9 species examined. muscle samples were collected from carcasses of 56 carnivores from 1993 to 1995 and frozen before transport and examination. following artificial digestion of the samples, collected larvae were analyzed by the random amplified polymorphic dna technique. trichinella nelsoni was identified in 1 bat-eared fox (otocyon megalo ...	1997	9406805
social facilitation, affiliation, and dominance in the social life of spotted hyenas.		1997	9071350
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
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
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
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 d ...	1998	9839878
androgens and masculinization of genitalia in the spotted hyaena (crocuta crocuta). 1. urogenital morphology and placental androgen production during fetal life.	according to common understanding of sexual differentiation, the formation and development of a penile clitoris in female spotted hyaenas requires the presence of naturally circulating androgens during fetal life. the purpose of the present study was to determine potential source(s) of such fetal androgens by investigating the timing of urogenital development and placental production of androgen during early and mid-gestation. fetuses determined to be female by molecular techniques (lack of sry ...	1998	9713383
personality dimensions in spotted hyenas (crocuta crocuta).	personality ratings of 34 spotted hyenas (crocuta crocuta) were made by 4 observers who knew the animals well. analyses suggest that (a) hyena personality traits were rated with generally high reliability; (b) 5 broad dimensions (assertiveness, excitability, human-directed agreeableness, sociability, and curiosity) captured about 75% of the total variance; (c) this dimensional structure could not be explained in terms of dominance status, sex, age, or appearance; and (d) as expected, female hyen ...	1998	9642781
estrogen: consequences and implications of human mutations in synthesis and action.	recent developments have advanced our knowledge of the role of estrogen in the male. studies of the mutations in cyp19, the gene encoding aromatase, in six females and two males and a mutant estrogen receptor alpha in a man are described. these observations provide illuminating new insights into the critical role of estrogen in the male (as well as female) in the pubertal growth spurt and skeletal maturation, and in the importance of estrogen sufficiency in the accrual and maintenance of bone ma ...	1999	10599737
carnivores from the early pleistocene hominid-bearing trinchera dolina 6 (sierra de atapuerca, spain).	the carnivores from trinchera dolina level 6 (td6) in sierra de atapuerca include ursus sp., crocuta crocuta, mustela palerminea, lynx sp., canis mosbachensis and vulpes praeglacialis. approximately 80 human remains belonging to homo antecessor were found in the aurora stratum (as): located in the upper part of the td6 level (td6, t36-43). the carnivores from as are taxonomically similar to the rest of the td6 level, differing only in the occurrence of lynx sp. the spotted hyaena (crocuta crocut ...	1999	10496995
vocal recognition in the spotted hyaena and its possible implications regarding the evolution of intelligence.	spotted hyaenas, crocuta crocuta, are gregarious carnivores whose social lives share much in common with those of cercopithecine primates. we conducted playback experiments to determine whether free-living hyaenas are capable of identifying individual conspecifics on the basis of their long-distance vocalization, the 'whoop'. when prerecorded cub whoops were played to mothers and other breeding females (controls), mothers responded significantly more vigorously to whoops of their own cubs than d ...	1999	10458890
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
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
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
a sex difference in the hypothalamus of the spotted hyena.		1999	10526331
the story of the spotted hyena and the hermaphrodite: biological order and enigma.	the complex problem of genital masculinization is illustrated in this article from the perspectives of comparative zoology, and pediatric plastic surgery on intersex children. in addition, criticism and recommendations coming from patient internet communications are introduced into the medical community.	2000	10994184
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
predator avoidance, breeding experience and reproductive success in endangered cheetahs, acinonyx jubatus.	i examine three hypotheses about predator avoidance behaviour: (1) avoidance increases an individual's reproductive success; (2) avoidance changes with breeding experience according to one of three described models; and (3) any reproductive or experience benefits accrued to individuals by avoidance are reflected in their spatial distribution. these hypotheses were tested on cheetahs which incur substantial juvenile mortality from predation by two larger competitors: spotted hyaenas, crocuta croc ...	2000	10924211
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 soc ...	2001	11742089
carnivore voiding: a taphonomic process with the potential for the deposition of forensic evidence.	carnivore defecation and regurgitation are taphonomic processes that create discrete concentrations of bone pieces and soft tissue fragments of animals that have been consumed. experiments in which baboon carcasses were fed to leopards and spotted hyenas demonstrate that primate metapodials and phalanges are well represented as readily identifiable specimens in such scat concentrations. most often phalanges are recovered from scat as whole, articulated digit units (composed of the proximal throu ...	2001	11305453
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
social, state-dependent and environmental modulation of faecal corticosteroid levels in free-ranging female spotted hyenas.	little is known about to what extent the sensitivity of the hypothalamic-pituitary-adrenal (hpa) axis may be state dependent and vary in the same species between environments. here we tested whether the faecal corticosteroid concentrations of matrilineal adult female spotted hyenas are influenced by social and reproductive status in adjacent ecosystems and whether they vary between periods with and without social stress. females in the serengeti national park frequently become socially subordina ...	2001	11747563
sexual mimicry in hyenas.	genital masculinization in female spotted hyenas has been widely explained as an incidental consequence of high androgen levels. high androgen levels, in turn, were supposed to be favored because they led to adaptive aggressive behavior. incidental androgenization is no longer a tenable hypothesis, however, because genital masculinization has been shown to proceed in the absence of androgenic steroids. thus, an alternative hypothesis is required. the genitals of spotted hyena females are not sim ...	2002	11963460
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
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
virilization of the female spotted hyena cannot be explained by alterations in the amino acid sequence of the androgen receptor (ar).	the external genitalia of the female spotted hyena are male in character, consistent with virilization by androgens during embryogenesis that results in the fusion of the vaginal labia to form a pseudo scrotum and enlargement of the clitoris to form a phallus. explanations advanced to account for these anatomic differences have centered on the production or metabolism of androgens in utero or on abnormalities of the androgen receptor (such as a constitutively active ar). the structure of the spo ...	2002	12242031
intersexual dominance, masculinized genitals and prenatal steroids: comparative data from lemurid primates.	masculinization of female genitalia and female intersexual dominance distinguish spotted hyenas (crocuta crocuta) and malagasy primates (lemuriformes) from most other mammals. an unusual prenatal endocrine environment has been proposed to proximately underlie the development of these traits in hyenas. to examine whether female dominance and genital masculinization are similarly enhanced by the prenatal environment in lemurid primates, we measured androgen and estrogen excretion in pregnant wild ...	2003	12649757
coprologic survey of parasites of spotted hyenas (crocuta crocuta) in the masai mara national reserve, kenya.	seventy fecal samples from spotted hyenas (crocuta crocuta) in the masai mara national reserve, kenya were examined for parasite eggs and oocysts using sugar flotation. a total of nine parasite genera were identified, and all samples were positive for at least one parasite species. most individuals were infected with ancylostoma sp. and spirometra sp., and these species had the highest median intensity of infection. other parasites identified include isospora sp., taeniidae, spirurida, toxocara ...	2003	12685088
antibodies to neospora caninum in wild animals from kenya, east africa.	the prevalence of antibodies to neospora caninum was examined in six wild artiodactyla species, and in five wild carnivora species from kenya. blood sera (104 wild ungulates from marula estates (mes), and 31 wild carnivores from masai-mara reserve and from other wildlife areas in northern and southern kenya), were screened using a neospora agglutination test (nat), with a twofold dilution (1:40-1:320 titres). presence of nat antibodies to n. caninun is reported here for the first time in zebra ( ...	2003	14651874
dermatophytosis in three colony-born spotted hyenas.	an adult female hyena and her two 4-month-old cubs were found to have multifocal areas of alopecia and dermatitis. dermatophyte culture of hair and skin samples collected from the lesions yielded trichophyton mentagrophytes. none of 10 other animals in the colony that were tested were found to have dermatophytes. lesions were treated twice, at 3-week intervals, with thorough cleansing with chlorhexidine scrub followed by topical application of antifungal agents. lesions resolved, and dermatophyt ...	2003	14690212
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
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
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
intrinsic qualities of primate bones as predictors of skeletal element representation in modern and fossil carnivore feeding assemblages.	plio-pleistocene faunal assemblages from swartkrans cave (south africa) preserve large numbers of primate remains. brain, c.k., 1981. the hunters or the hunted? an introduction to african cave taphonomy. university of chicago press, chicago suggested that these primate subassemblages might have resulted from a focus by carnivores on primate predation and bone accumulation. brain's hypothesis prompted us to investigate, in a previous study, this taphonomic issue as it relates to density-mediated ...	2003	12727462
social status does not predict corticosteroid levels in postdispersal male spotted hyenas.	in social species with low rates of direct male competition levels of corticosteroids should not correlate with social status. male spotted hyenas acquire social status by observing strict queuing conventions over many years, and thus levels of male-male aggression are low, and male social status and tenure are closely correlated. in this study, we investigated whether the low rate of direct male competition in spotted hyenas was reflected in fecal corticosteroid levels of adult males in the ser ...	2003	12788293
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
antibodies to canine and feline viruses in spotted hyenas (crocuta crocuta) in the masai mara national reserve.	spotted hyenas (crocuta crocuta) are abundant predators in the serengeti ecosystem and interact with other species of wild carnivores and domestic animals in ways that could encourage disease transmission. hyenas also have a unique hierarchical social system that might affect the flow of pathogens. antibodies to canine distemper virus (cdv), feline immunodeficiency virus (fiv), feline panleukopenia virus/canine parvovirus (fplv/cpv), feline coronavirus/ feline infectious peritonitis virus (fecv/ ...	2004	15137483
coronavirus infection of spotted hyenas in the serengeti ecosystem.	sera from 38 free-ranging spotted hyenas (crocuta crocuta) in the serengeti ecosystem, tanzania, were screened for exposure to coronavirus of antigenic group 1. an immunofluorescence assay indicated high levels of exposure to coronavirus among serengeti hyenas: 95% when considering sera with titer levels of > or = 1:10 and 74% when considering sera with titer levels of > or = 1:40. cubs had generally lower mean titer levels than adults. exposure among serengeti hyenas to coronavirus was also con ...	2004	15288921
separation as a natural cue to danger in the spotted hyena (crocuta crocuta).	spotted hyena biology suggests mothers and infants will exhibit one of two alternative responses to separation: (a) due to prolonged dependency, infants will act similarly to old world monkeys, displaying distress and proximity seeking behaviors; or (b) because mother-infant separations are frequent in the wild, infants will exhibit little distress or change in reunion behavior. hence, reunion behavior following mother-infant separation was compared to control periods in captive hyena (crocuta c ...	2004	15054888
behavioural structuring of relatedness in the spotted hyena (crocuta crocuta) suggests direct fitness benefits of clan-level cooperation.	spotted hyenas (crocuta crocuta) are gregarious carnivores that live in multigenerational social groups, called clans, containing one to several matrilines. members of multiple matrilines within a clan cooperate during dangerous interactions with inter- and intraspecific competitors. the evolution of cooperation may be influenced by relatedness between individuals, which in turn is influenced by reproductive skew and mate choice, dispersal and territorial behaviours. behavioural data exist for s ...	2004	14717899
erythema multiforme in a spotted hyena (crocuta crocuta).	a 10.5-yr-old male spotted hyena (crocuta crocuta) developed acute, severe erythematous and ulcerative dermatitis of the hindquarters, feet, face, and ears 19 days after receiving a recombinant canary pox vectored canine distemper vaccine. biopsies of the lesions supported a diagnosis of erythema multiforme (em), which is an immune-mediated disorder that can occur days to months after exposure to antigenic stimuli. during the lengthy recovery, esophageal regurgitation and ulceration developed ei ...	2005	17312775
karyotypic conservatism in the suborder feliformia (order carnivora).	multidirectional comparative chromosome painting was used to investigate the karyotypic relationships among representative species from three feliformia families of the order carnivora (viverridae, hyaenidae and felidae). complete sets of painting probes derived from flow-sorted chromosomes of the domestic dog, american mink, and human were hybridized onto metaphases of the spotted hyena (crocuta crocuta, 2n = 40) and masked palm civet (paguma larvata, 2n = 44). extensive chromosomal conservatio ...	2005	15627756
seroprevalence and genomic divergence of circulating strains of feline immunodeficiency virus among felidae and hyaenidae species.	feline immunodeficiency virus (fiv) infects numerous wild and domestic feline species and is closely related to human immunodeficiency virus (hiv) and simian immunodeficiency virus (siv). species-specific strains of fiv have been described for domestic cat (felis catus), puma (puma concolor), lion (panthera leo), leopard (panthera pardus), and pallas' cat (otocolobus manul). here, we employ a three-antigen western blot screening (domestic cat, puma, and lion fiv antigens) and pcr analysis to sur ...	2005	15956574
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
the population history of extant and extinct hyenas.	we have analyzed partial dna sequences of the mitochondrial cytochrome b gene from extant striped, brown, and spotted hyenas as well as from pleistocene cave hyenas. sequences of the pleistocene cave hyenas from eurasia and modern spotted hyenas from africa are intermixed in phylogenetic analyses, questioning any taxonomic delineation between the two groups. contrary to cave hyenas in eurasia, spotted hyenas in africa show a phylogeographic pattern with little geographical overlap between two mi ...	2005	16120805
on sexual behavior and sex-role reversal.	sex is not about reproduction; sex is about (re-)combination of dna. sex, not reproduction, always involves physical contact between two individuals; to achieve this, strategies of sexual behavior evolved. sexual behavior, therefore, did not evolve as part of a reproductive strategy, but evolved to enable exchange of genetic material. in multicellular organisms the situation is more complicated than in unicellular organisms, as it is impossible for each cell within a multicellular body to have s ...	2005	16295520
sexual differentiation in three unconventional mammals: spotted hyenas, elephants and tammar wallabies.	the present review explores sexual differentiation in three non-conventional species: the spotted hyena, the elephant and the tammar wallaby, selected because of the natural challenges they present for contemporary understanding of sexual differentiation. according to the prevailing view of mammalian sexual differentiation, originally proposed by alfred jost, secretion of androgen and anti-mullerian hormone (amh) by the fetal testes during critical stages of development accounts for the full ran ...	2005	16197946
distribution of vasopressin in the forebrain of spotted hyenas.	the extreme virilization of the female spotted hyena raises interesting questions with respect to sexual differentiation of the brain and behavior. females are larger and more aggressive than adult, non-natal males and dominate them in social encounters; their external genitalia also are highly masculinized. in many vertebrates, the arginine vasopressin (vp) innervation of the forebrain, particularly that of the lateral septum, is associated with social behaviors such as aggression and dominance ...	2006	16856162