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| Spotted Hyena - Crocuta Crocuta | |
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| Tweet Topic Started: Jan 7 2012, 08:21 AM (35,722 Views) | |
| Canidae | Jan 9 2012, 08:27 PM Post #16 |
Omnivore
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  Young Giraffe kill, by Frank & Witleos Edited by Canidae, Jan 9 2012, 08:47 PM.
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| Canidae | Jan 9 2012, 08:28 PM Post #17 |
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More hyena info from Frank - A hyena lives in a social group known as a "clan" these clans are composed of a dominant female, followed by her cubs, and the second most dominant female, followed by her cubs and so on. Although hyenas are scavengers, they also do a lot of hunting and are more kleptoparasetic then carrion eaters. Hyenas are also thought to be amazingly intelligent and they have at least eleven vocal sounds that they make, although there can be up to thirteen (still debatable). A hyena can hide meat in water for days before returning to the same spot to eat it, and memorize the indivisual identification of eighty other clan members ! There jaws are also thought to be the most powerful amongst mammalian carnivores, a hyena can bite threw a cape buffalos thigh bone as if it was a knife cutting threw butter. Females are larger then males because of there increased testosterone level, it reaches so high that females evolved there genetalia being closer to that of males (althought there chromosomes still in fact do read (x,x)) which made much more aggressive, and ultimatley gave the females more masculine features. Hyenas are also highly territorial and will kill other hyenas outside of there clan. Despite modern legend, hyenas are very aggressiev and 25 % of the cubs in a hyena litter are killed by there siblings for battles over dominance. A hyena has stomache acid with a ph of nearly 1 and can melt down pieces of pots and pans. A hyena has 34 bulky, and resistant teeth. When a hyena whoops, data collected shows that each hyena has its own indivisual whoop and a females whoop is often given more attention to then a males. Hyenas can gallop at speeds of 25-31 mph, and can run and reach a top of 37 mph. Hyenas trot at a speed of 6 mph. 
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| Canidae | Jan 9 2012, 08:32 PM Post #18 |
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Spotted Hyena (left) skull comparison with 550lb Black Bear and large male Alaskan Grey Wolf, O.P'ed by Dinocrocuta   
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| Canidae | Jan 9 2012, 08:33 PM Post #19 |
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Frank's info on Lion Predation (first section) and hyena reproduction (second section) - Spotted hyenas are successful hunters, but they also scavenge. Their main food competitors are lions. In the Etosha National Park, Namibia hyenas are unable to prevent kleptoparasitism by lions and fail to acquire kills from lions. The reasons are the small ratio of hyenas to female and subadult lions at kills and the presence of adult male lions. Because of the hyenas' small clan sizes and large territories they seem to be unable to recruit sufficient clan members to take over lion kills or deter lions from their own kills. In Etosha, 71% of hyena mortality was due to lions; four cubs and one adult female hyena were killed by male lions during a 1-year study. Hyenas have evolved adaptations against lions and initiate aggressive interactions with lions without the immediate availability of food, which is termed mobbing behaviour. Etosha hyenas initiated mobbing attempts when lions were near the hyena's communal den. Possibly, Etosha hyenas mobbed lions to distract lions from the hyenas' den and their cubs and to warn their dependent offspring to hide from lions http://www.ingentaconnect.com/content/bsc/afje/2005/00000043/00000003/art00010 ---------------------------------------------------------------------------------------------------------------------- Sex and the Spotted Hyena by Robin Meadows Face to face with the spotted hyenas in the Berkeley hills, I find it hard to believe that these are the fearsome creatures I've been reading about for weeks. Where are the bone-crushing jaws and the propensity for a pack to strip a zebra in 15 minutes flat? These hyenas are fat and friendly, and are clearly interested in their human visitors, in a nonthreatening way. When biologist Laurence Frank enters an enclosure, he is encircled by three exuberant hyenas that look for all the world like large, shaggy, undisciplined dogs in search of love. My daughters and I are equally charmed. After my initial astonishment at the hyenas' amiability, however, I realize that this reception is not at all surprising. Frank bottle-raised this trio, which means he is the closest thing to a mother they have. In the mid-1980s, Frank and his colleague Stephen Glickman captured 20 infant spotted hyenas in Kenya and brought them home to the University of California at Berkeley. The two researchers rightly anticipated that studies of captive hyenas would unravel the mysteries of these animals, which have been famous since the time of Aristotle for being hermaphrodites. The misconception that spotted hyenas are bisexual was perpetuated well into the twentieth century by people from Hemingway, who as a writer of fiction can be excused, to biologists, who should have known better. The truth about spotted hyenas (Crocuta crocuta) is arguably as bizarre as the myth. To the untrained eye, females look and act almost exactly like males. The two sexes' remarkable resemblance goes right down to the nitty-gritty of their genitals, which appear to be identical. Moreover, the females of this species seem to be even more masculine than the males: Females are some 10 percent larger by weight and are so much more aggressive that they dominate males in nearly every social encounter, a fact that the Disney studio paid only lip service to when developing the hyena characters for last summer's animated movie "The Lion King." While the hyenas' ringleader was indeed female, her goofy sidekick should have been named Edwina rather than Ed. The Disney studio had ample opportunity to get it right because a team of illustrators came to Berkeley to sketch Frank and Glickman's brood. More than mere curiosities, spotted hyenas challenge the conventional wisdom of what makes us female or male and so can give us insights into the limits and latitudes of our own sexuality. Many biologists who study female-male differences let their preconceptions affect their results. For instance, while testosterone and other so-called "male" hormones are quite common in female mammals, biologists almost always focus on their estrogen and other so-called "female" hormones, notes Frank. Despite their dog-like appearance, the three species of hyenas belong to a superfamily that includes cats, mongooses, and civets. Spotted hyenas are named for the dark brown spots that stand out against their short, brownish-yellow fur. The demented-sounding cackle they make when squabbling gives them their other common name, the laughing hyena. Spotted hyenas live in the savannas and woodlands of sub-Saharan Africa, and their range overlaps with those of the other two species of hyenas, the striped and brown hyenas (Hyaena hyaena and Parahyaena brunnea). All three species have the long necks, powerful shoulders, and short hindlegs that give hyenas their characteristic attenuated look. Likewise, all hyenas are consummate scavengers, noteworthy for being the only carnivores that can ingest a carcass in its entirety. While carnivores' digestive tracts are typically short, those of hyenas are uncommonly long and are capable of extracting nearly all the protein and fat from bones. The mineral components of bone are reduced to a fine powder that is excreted, while the hair, ligaments, and other undigestible body parts are regurgitated in a pellet. Spotted hyenas are distinguished from their relatives in two major ways. While striped and brown hyenas supplement their diets by catching small prey from insects to foxes, these species are predominantly scavengers. In contrast, spotted hyenas hunt for most of their food and usually prey on large animals. A single spotted hyena can catch an adult wildebeest after chasing it three miles at speeds of up to 35 miles per hour. The second major difference is, as already mentioned, that female spotted hyenas have in many ways adopted the orthodox male role. Female spotted hyenas bear, suckle, and care for their young like any female mammal. But although their genitals are clearly female in function, they are male in form. The labia are fused into what looks like a scrotum, complete with two pads of fatty tissue that resemble testes. In addition, the clitoris is elongated to the point that it is nearly the size of a male's penis and is likewise fully erectile. Astonishingly, females mate and give birth through the long, narrow canal running down the center of this "pseudopenis." During mating it retracts much like a shirt sleeve being pushed up, and during birth it stretches so much that it looks like a water balloon. "From a human perspective, the process can be thought of as giving birth through an unusually large penis," says Frank. While highly unusual, spotted hyenas are not as anomalous as they appear to be at first glance. Rather, they are at the extreme end of a continuum of female mammals with masculine characteristics. One-quarter of mammalian families contain species in which females are larger than males, and there are other female mammals with genitals that are masculinized to some degree. For instance, spider monkeys have a large, pendulous clitoris and the European mole has an elongated penis-like clitoris. In addition to having male-like genitals, female spotted hyenas enjoy the social position accorded to males in most mammal species: dominance. Except for when they are ready to mate, female spotted hyenas completely dominate the adult males that join their clan. (As is true of many social mammals, female hyenas stay in the clan where they were born while males disperse when they reach puberty at about two years of age.) Most tellingly, males abandon kills once females show up--Frank has seen a single juvenile female keep five full-grown males from feeding on a buffalo carcass. Males typically skirt the edges of kill sites, snatching scraps dropped by females. Aggression is a way of life for female spotted hyenas. "Rank is inherited from mothers, and higher-ranking females teach youngsters what their rank is through aggression," says Frank. "A mother-daughter pair or two sisters will attack a subordinate when her young are around [which teaches the subordinate's young where they stand]." Dominant females threaten a subordinate by walking toward her shoulder-to-shoulder with their manes and tails raised. While many such displays are just meant to show who's boss, subordinates sometimes sustain considerable damage. After being separated for a few hours, spotted hyenas engage in "greeting" displays that entail lifting their legs and exposing their erect pseudopenises for inspection. Subordinate females often initiate greetings and this is the only known case of an erection being a submissive gesture. "This unusual display is not without its risks [because] each hyena puts its reproductive organs in immediate proximity to very powerful jaws," says Frank. "On the rare occasions when the aggression escalates to fighting, the resulting damage may be severe enough to destroy or seriously compromise the reproductive competence of the injured party." The big questions about spotted hyenas are obvious. Why do the females sport such extraordinary anatomy and behavior? And why are hyenas the only mammals with females that are masculinized to such an extreme degree? Attempts to answer the first question were confounded until Frank, who coordinates the field work, and Glickman, who directs the project, established their hyena colony. Studies on the 40-odd captive hyenas are explaining the physiological basis of behaviors that Frank and his colleagues have seen in their 16-year field study of spotted hyenas in the Talek clan living in Kenya's Masai Mara National Reserve. One of Frank and Glickman's most striking findings is that compared to males, female spotted hyenas have much higher blood levels of a steroid hormone called androstenedione, which is an androgen or classically "male" hormone. Androstenedione is particularly interesting because it can be metabolized into either the "male" hormone testosterone or the "female" hormone estrogen depending on what enzyme is present: One enzyme converts androstenedione to estrogen, while another converts it to testosterone. Placentas typically contain both enzymes but Glickman, University of California at Berkeley endocrinologist Paul Licht, and colleagues at the University of California at San Francisco, found that the balance is skewed in spotted hyenas. Human placentas (and presumably those of most mammals) convert maternal androgens to estrogen, thus protecting female fetuses from being masculinized. Spotted hyena placentas, on the other hand, actually convert the maternal androstenedione to testosterone. Testosterone's effect on female fetuses has been well-documented in laboratory studies. Prenatal exposure to testosterone in female rats, dogs, and monkeys causes male-like genitals as well as increased body size, aggression, and dominance--in short, the suite of characteristics found in female spotted hyenas. However, science is just like any other part of life in that the answers are not always easy. As the pundits say, there are three kinds of logic: deductive, inductive, and "seductive," that is, plausible but not necessarily true. The third kind of logic may apply to the argument that female spotted hyenas are masculinized due to prenatal exposure to testosterone. "Everything we know about sexual differentiation is simple: Testosterone makes males," says Frank. "But because of a whole series of hints, it looks like that may not be the whole picture in spotted hyenas." One of these hints is that treatments that reduce penis size in other species--prenatal exposure to compounds that inhibit androgens, and castration before puberty--have little effect on genital size in either sex in spotted hyenas. Such findings have led the researchers to speculate that, "an as yet undiscovered novel mechanism may contribute to sexual differentiation in this species." That is, the answers are not yet in on what separates the girls from the boys. Frank and Glickman's studies of the captive spotted hyenas have also led to the surprising discovery that they fight violently at birth. The young of predatory birds including boobies, eagles, and egrets are known to attack and ultimately kill their younger siblings soon after hatching, which may be because the second egg serves only as parental insurance in case the first fails to hatch. However, this is the first such case known in mammals. Spotted hyenas typically give birth at the mouths of abandoned aardvark burrows, which are filled with passages that narrow as they diverge from the entrance. While the burrows protect the babies from lions and other hyenas, the narrow passages also prevent the mother hyena from reaching her cubs. When ready to nurse, she lies at the entrance and makes a low, groaning sound to call her babies to the surface. After the baby hyenas have lived in the security of their burrow for a few weeks or so, their mother carries them to a communal den shared by other hyena young. Although spotted hyenas usually have twins, observations during the first decade of the Talek clan field study showed that mothers brought many more single cubs to the communal den than expected. Instead of being mostly twins, by a few weeks of age, more than 40 percent of the litters comprised lone cubs. What was happening during those initial weeks in the aardvark burrows where the cubs were born? Because the narrow passages make the burrows inaccessible to predators and biologists alike, Frank was unable to solve this puzzle until the first hyenas were born in the Berkeley colony. Then he saw that unlike most carnivores, which are helpless at birth, spotted hyenas are born with both the equipment and inclination to attack. Their eyes are open, their incisors and canine teeth are fully erupted, and they are able to bite within minutes of birth. And bite they do, dotting each other's shoulders and necks with tell-tale puncture wounds until dominance is established. This aggression notwithstanding, spotted hyenas don't kill their siblings directly. Rather, the subordinate sibling is so cowed by the constant attacks that it stays away from the burrow entrance and so from its mother, which means it ultimately starves to death. In the wild, as many as one-quarter of all cubs apparently die in the depths of their natal aardvark burrows. While Frank and Glickman have made considerable progress in determining the physiological basis for the female spotted hyenas' masculinization, the answer to why spotted hyenas are the only mammals with females that are so extremely masculinized is not as clear. The generally accepted theory is that the masculinization is a consequence of the species' highly competitive communal feeding. Higher-ranking females and their young get to eat first, and the argument goes that this favors increased aggression in females, which in turn favors increased "male" hormones in females. According to this scenario, the females' masculinized genitals and intense aggression from birth are just side-effects of the increased androgens. However, Frank cautions that many other carnivores also eat together, suggesting that competition for food is not the only reason behind the female spotted hyena's masculinization. "The ancestral spotted hyenas' endocrinology must have preadapted them to this development," says Frank. Whatever the cause, female masculinization is apparently a very successful strategy for the spotted hyena, which is the most abundant large predator in its range. But this success comes at a cost that is tremendously high for the spotted hyena--and presumably prohibitively high for other species. Notably, giving birth is difficult and dangerous, especially for first-time mothers. The fact that the pseudopenis has such a long, narrow birth canal is enough to make it a poor organ for delivering a baby. But there is the added complication that the end of the pseudopenis cannot stretch enough to accommodate passage of the baby: In a first-time mother, the baby tears its way out. "It's the only time I've ever heard hyenas cry out in pain," notes Frank. Even worse, the umbilical cords are so short that many first-born babies die. At only six-inches long, the umbilical cord is far too short to traverse the foot-long canal down the pseudopenis, which means that either the placenta detaches or the cord breaks before the baby is born. (For comparison, in women the birth canal is only a few inches long and the umbilical cord is a generous foot and a half long.) The longer a hyena's labor, the more likely her baby is to suffocate and be stillborn--and the more likely the mother is to die. In captivity, first-time mothers labor as long as 48 hours and nearly three-quarters of first-born cubs die. Without veterinary help, many of these mothers probably would have died along with their babies; in the wild, many females die at three to four years, the age when hyenas typically first give birth. The high rate of siblicide is another significant cost to the female spotted hyena's masculinization. Producing babies that die shortly after birth is a tremendous waste of a mother's energy. Intriguingly, female spotted hyenas have apparently managed to wring what advantage they can out of their babies' inclination to kill each other. Frank believes that mothers use siblicide to manipulate the sex ratio of their offspring. It is well known that many female mammals bias the sex ratio of their offspring. Biologists speculate that, for example, having sons may be advantageous to bushbabies, muskrats, and other species in which daughters grow up to share territories with--and so compete for resources with--their mothers. Frank found that high-ranking females in the Talek clan generally raised more sons than daughters when the population of the clan was high. But since 1990, when about a third of the adult females left to establish a new clan, high-ranking females in the Talek clan have raised more daughters than sons. However, while most species somehow adjust the sex ratio before their babies are born, spotted hyenas appear to adjust the sex ratio of their babies after birth. Frank has seen that in the wild, female spotted hyenas sometimes put newborn twins into separate aardvark burrows, which keeps the babies from fighting and so greatly increases the likelihood that both will survive. The implication is that mother hyenas can intervene and save their babies if they are the desired sex. Ever since they were mistaken for hermaphrodites, spotted hyenas have been among the most misunderstood species on earth. Most people follow the lead of the Disney script-writers and cast hyenas as the bad guys of the animal world for their gruesome lifestyles. But as Frank and Glickman's work shows, the qualities for which they are reviled seem to arise from a noble goal: Like any mothers, the female hyenas are just trying to provide the best for their children. As for the rest, spotted hyenas, like many of us, are largely captives of their biology. Robin Meadows is a contributing editor to ZooGoer. (ZooGoer 24(3) 1995. Copyright 1995 Robin Meadows. All rights reserved.) http://nationalzoo.si.edu/Publications/ZooGoer/1995/3/sexandthespottedhyena.cfm  |
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| Canidae | Jan 9 2012, 08:34 PM Post #20 |
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Parasites & Spotted Hyena, O.P'ed by Frank -   |
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| Canidae | Jan 9 2012, 08:35 PM Post #21 |
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Hyena foraging, O.P'ed by Taipan - Solitary Hyenas still get the last laugh By Greg Soltis, LiveScience Staff posted: 17 July 2008 04:44 pm ET Spotted hyenas lived as solitary scavengers over a million years ago. But over time, they have become more of a communal species. New research indicates that, to offset the cost of competition among the group, spotted hyenas still demonstrate an ancestral tendency to separate themselves when searching for their next meal. Hyenas do find some strength in numbers in several ways. They may engage in turf battles with other local hyenas. Tracking down a meal is certainly easier as a group effort – spotted hyenas are 20 percent more likely to capture prey if they have help. And this collective approach then bodes well when defending their newly acquired food from lions. But with these advantages come drawbacks as well. Additional help before the kill translates into additional competition afterwards. And with a well-established hierarchy, the spotted hyenas higher up the ladder get their meal while others suffer. Consequently, hyenas still head out for food but later return to their community. This cyclic process of splitting up and then reuniting, similar to humans who return home after work, is referred to as fission-fusion dynamics. Jennifer Smith, a doctoral zoology student at Michigan State University, recently published a paper in the journal Animal Behavior that offers these results. She based her work on research performed at Masai Mara National Reserve in Kenya. Michigan State University zoology student Brittany Gunther took this photo of a fight between a group of spotted hyenas and a lioness while taking a study abroad class at Kenya’s Masai Mara National Reserve. http://www.livescience.com/animals/080717-spotted-hyena.html |
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| Canidae | Jan 9 2012, 08:36 PM Post #22 |
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Prey preference, by Reddhole - Spotted Hyena Here is the study: http://www.zbs.bialowieza.pl/publ/pdf/1598.pdf Here is the abstract: Abstract Spotted hyaenas Crocuta crocuta were once considered mere scavengers; however, detailed research revealed that they are very efficient predators. Information on what spotted hyaenas actually prefer to prey on and what they avoid is lacking, as well as the factors that influence prey selection. Data from 14 published and one unpublished study from six countries throughout the distribution of the spotted hyaena were used to determine which prey species were preferred and which were avoided using Jacobs’ index. The mean of these values for each species was used as the dependent variable in multiple regression, with prey abundance and prey body mass as predictive variables. In stark contrast to the rest of Africa’s large predator guild, spotted hyaenas do not preferentially prey on any species. Also surprisingly, only buffalo, giraffe and plains zebra are significantly avoided. Spotted hyaena most prefer prey within a body mass range of 56–182 kg, with a mode of 102 kg. The dietary niche breadth of the spotted hyaena is similar to that of the lion Panthera leo, and the two species have a 58.6% actual prey species overlap and a 68.8%preferred prey species overlap. These results highlight the flexible and unselective nature of spotted hyaena predation and are probably a reason for the species’ success throughout its range, despite a large degree of dietary overlap with lions. Here are the details on the specific prey species. Species with a small + or - next to them have enough data to be "statistically significant" (i.e. buffalo, giraffe).  |
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| Canidae | Jan 9 2012, 08:37 PM Post #23 |
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Hyena hunts Baboon, O.P'ed by Taipan - VeldFocus Hyena Hunts Baboon Date: Sunday, January 25, 2004 Producer: Ronnie Watt E-mail: veldfocus@iafrica.com Jakkie Spano of Newcastle videoed a scene of a hyena hunting a baboon… and that is not a common sight! The event took place at Maroela Camp in the Kruger national Park where a troop of baboons were feeding on the fruit of a Maroela tree. A camp staff member chases them off but one female lingers behind… to her detriment. Out of the blue a lone hyena attacks her, and that’s where Jakkie’s video starts. At first the hyena has the baboon firmly clasped by her mouth and drags it along. She is trying to free herself with her hands but it is futile. The hyena then stops and changes grip… this time it bites down on the skull in the area of the eye. The baboon offers little resistance… every now and then there is some feeble thrashing. Of interest is that the hyena does not immediately start to feed on the baboon. Usually when in a group, hyenas will start ripping flesh as soon as prey is subdued. But this is not the case here. The baboon has formidable incisors that can inflict serious wounds and so the hyena hangs on until it is sure that its prey is incapacitated. Again it drops the baboon… and as soon as it realises that there is still life, the hyena grasps it again firmly. It looks as though it uses its body weight to press down onto the baboon. Only after it is sure there is no life left, does it rise and carry the carcass off. It is not often that hyenas are successful in hunting baboons. A baboon troop has a formidable defense strategy and the dominant males or lookouts will come to the rescue of any individual in distress. I am sure that the hyena’s initial firm grip on the baboon’s mouth prevented her from uttering distress calls. The subsequent vise-like grip on the skull might even have allowed the powerful teeth to penetrate the bone and damage the central nervous system.  |
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| Canidae | Jan 9 2012, 08:37 PM Post #24 |
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Hyena mass, O.P'ed by Manics - From "Mammals of southern Africa" Zimbabwe Males 57.8kg range=49-66.3kg Females 64.8kg range=55.8-76.7kg Kruger Males 62.5 range 54-70kg Females 68.2kg range 55-81kg Kwazulu Males 66.6kg range 55-79kg Females 70kg range 56-80kg Kalahari Males 59kg range 55.8-62.5kg Females 70.9kg Range 67.1-75kg I didnt realise Hyenas were so large. Theres not a huge difference in size between the sexes although females are clearly larger. The largest Male leopards were from Kruger. Older males weighed average 63.1kg and females 37.2kg. In Zimbabwe male leopards weighed 59.7kg (52.8-71.3kg) Females only weighed 31.5kg (28.2-34.9kg) Its easy to see why female leopards almost never stand up to even a solitrary hyena for food. Although it emphasises how impressive this is considering the size disparity. |
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| Canidae | Jan 9 2012, 08:40 PM Post #25 |
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Prey selection by Reddhole - Summary: This study shows that spotted hyenas hunt most of their prey in the Namib desert. It also shows that the main prey are gemsbok and mountain zebra. Old adults of both species are targeted, but young/immature animals are also likely taken frequently. Male gemsbok are targeted due to rut injuries and female mountain zebra are preferred because they are less aggressive than stallions. Source: Tilson, Blottnitz, and Henschel; "Prey Selection by the Spotted Hyena (Crocuta crocuta) in the Namib Desert"; Madoqua Vol. 12 No. 1 P 41-49 1980 Gemsbok and Mountain Zebra Comprise the Bulk of Hyena Diet Below is scat data. Gemsbok and zebra make up about 80% and 13% of spotted hyena diet.  The authors conclude that hyenas killed most of these animals because the prey populations were not dense (i.e. hard for hyenas to find carcasses) nor were these prey populations in extremely poor health (i.e. few carcasses available for hyenas).  Old Adult Male Gemsbok and Old Adult Female Zebra Targeted by Spotted Hyenas Below is the age/sex predation data. Note that the authors only concluded that half of these were definite hyena kills (see extract in section below). 23 of 29 gemsbok carcasses were 12 years or older. 16 of 26 mountain zebra were 8 years or older. 65% of gemsbok carcasses were males while 69% of mountain zebra carcasses were females.  The authors explain that hyenas preferred old male gemsbok and old female mountain zebra. In addition, the authors mention that many young, immature animals are also likely killed, but carcasses are hard to locate.   Hyena Predation in the Namib Desert « Reply #44 on Feb 12, 2009, 3:22am »
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| Canidae | Jan 9 2012, 08:44 PM Post #26 |
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Reddhole on Predation in Etosha NP - Summary: The study below shows that hyenas hunted 75% of their prey, but primarily killed smaller springbok (about 40 KG). Hyenas hunted in smaller groups (1-5 hyenas) and did not hunt adult zebra. Source: Gasaway, Mossestad, and Stander, "Food Acquisition by Spotted Hyenas in Etosha National Park, Namibia: Predation Versus Scavenging", African Journal of Ecology: Volume 29, P 64-75, 1991 Below is the study's abstract. Hyena-killed prey as a percentage of hyena diet in various studies is listed as 50%-98% and 75% in this one. Elsewhere in the study the details are listed as follows: Namib Desert (summarized in this thread): 50-93% Kruger: 51-60% Serengeti (summarized in this thread): 56-76% Kalahari: 72% Chobe: 70-80% Ngorongoro (summarized in this thread): 91-98% Springbok was the main prey killed and adult zebra were not killed.  Predation Details - Springbok Killed and Zebra Rarely Hunted The table below details hyena interactions with potential prey. Springbok were the most frequently encountered prey and were the prey most often hunted. Zebra were never tested or hunted. Hunting success can also be determined. Overall hunting success was 27% (3/11) and springbok hunting success was 22% (2/9) based on the number of hunts. However, this data is a great example why hunting success figures need to be scrutinized. For example, wolf hunting success is often based on all prey "tested", which yields a lower hunting success figure. If we measure hunting success by prey tested, then hunting success drops to 12.5% (3/24) overall and 11.1% (2/18) for springbok.   Hunting Groups Were Small, Zebra Were Avoided The data below shows hyenas mostly hunted in small groups of 1-5, 55% of which were single hyenas. Hyenas did not try to kill any adult zebra. Also, note how strict the definition of "test" and "hunt" are. IMHO, these strict definitions inflate hyena hunting success relative to other carnivores by lowering the number of "hunts" in these calculations.  Hyenas Avoided Adult Zebra Because Hyenas Did Not Hunt in Large Groups The author cites two studies, Kruuk (summarized in this thread) and Cooper, that show hyenas usually require groups of 5 or more to kill adult zebra. As a result, the author cites this as the reason why the small groups of hyenas in this study did not kill zebra.   |
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| Canidae | Jan 9 2012, 08:45 PM Post #27 |
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Hyena maturity, O.P'ed by Taipan - Studies Of Hyena Skull Development Put Teeth Into New Female Dominance Theory ScienceDaily (Mar. 31, 2009) — Getting between a female hyena and her cubs at chow time is no laughing matter – especially for males. Females rule among spotted hyenas, making them rare among mammals and unique among carnivores, Michigan State University researcher Kay Holekamp said. After more than 20 years of closely studying generations of the ferocious, yet social creatures, Holekamp and colleagues now believe they know why. "We've been unhappy with previous explanations of sex role reversal in hyenas for some time," said zoology professor Holekamp, who is recognized as a top authority on the spotted hyena. Holekamp and associates theorize that the length of time it takes for the massive skulls and jaws of hyenas to mature in youngsters – combined with the intense feeding competition typical of hyena clans – prompt female family members to develop dominant behaviors. "Mothers have to compensate with aggression for the handicaps their kids are experiencing during feeding," she said. Hyena cubs are at particular risk after they are weaned, she said, because their skulls don't fully develop until after sexual maturity. More closely related to cats than dogs, hyenas are most closely related to the animal family that includes mongooses. They can weigh up to 185 pounds and stand up to 3 feet tall, with jaws capable of cracking open giraffe leg bones up to 3 inches in diameter. Known mostly as scavengers and able to eat things that would sicken or kill many other species, they also are good hunters, capable of bringing down prey several times their own size. The complex social system established by spotted hyenas, which live in clans numbering up to 90 members, is a prime area of research in Holekamp's lab. Holekamp was joined in her research by Heather Watts, the report's lead author, and Jaime Tanner, both former Holekamp laboratory graduate students. Associate zoology professor Barbara Lundrigan, curator of mammalology and ornithology at the MSU Museum, lent her expertise on skull development and helped develop and test the group’s new hypothesis using many of the museum's 70-plus known-age hyena skulls. A report describing the researchers' theory is published in the March 18 issue of the Proceedings of the Royal Society B,  A mother spotted hyena and cub. http://www.sciencedaily.com/releases/2009/03/090331112851.htm |
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| Canidae | Jan 9 2012, 08:47 PM Post #28 |
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Omnivore
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Hyena attack on flamingo flock, O.P'ed by Taipan - Pictured: The incredible moment a hyena attacks a flock of flamingos By Daily Mail Reporter Last updated at 12:11 PM on 08th June 2009 Standing on the edge of a Kenyan lake, the hundreds of pink flamingos are enjoying a relaxing rest and a leisurely feast. And then the atmosphere changes: the birds stiffen and then begin running across the shallow waters in a desperate bid to get airborne. Then the reason for their distress becomes obvious, as a hungry hyena bounds onto the scene and gives chase to the fleeing pink birds.  The chase is on... The hyena has found his victim, and the poor flamingo has no choice but to attempt a flight The fearsome predator shows a surprising turn of speed, plucking one unlucky bird straight from the air as it desperately tries to take flight. The dainty birds are fine at flying, but they need a run-up to get out of reach of the killer's claws. And as the hyena grabs a pink-feathered wing in its jaws, for this bird the chase is up.  But the poor flamingo has left it too late to make an escape, and the hyena makes a vicious kill The moment was captured by British photographer Anup Shah, who used a camera camouflaged as a boulder to get the bird's-eye view of the attack. He said: 'This is the first time anyone has tried this technique with a flamingo flock of having the camera right inside the flock. 'It was essential we did not disturb the bird's routine so that they acted entirely naturally for the shots.' He added: 'We had to camouflage the camera and keep it on a floating platform away from the damaging caustic lake waters. 'It was definitely worth it because we were able to get a real feel of what it is like to be a flamingo in a flock of millions. 'I was there when the hyena attacked, and it was unusual to watch. 'Hyenas are opportunistic hunters and they will try to catch flamingos but they do not have the protection from the burning effects of the lake like the birds do. 'They often attack in the morning when the birds are gathered in their greatest numbers near to the shore of the lake, because of fresh water rivers which flow there which they can drink from. 'The fitter birds are the ones which get away and get in the air quickly, it is the weaker ones which are in danger like the bird that was caught.'  Safety in numbers: The flamingos rush past the camera at full speed, each hoping to escape the jaws of the hungry predator Mr Shah added: 'It is amazing to capture a sequence like this on camera and even more so because you really get the feel of the panic in the flock because of the closeness of the lens. 'This particular group that was attacked had a few hundred individuals.' Lake Nakuru is one of the Rift Valley soda lakes. It lies to the south of Nakuru, in central Kenya and is protected by a small Lake Nakuru National Park. Its name means 'Dust or Dusty Place' in the native Maasai language. The pictures were shown to Wildlife and Wetland Trust's Nigel Jarrett, who looks after the biggest population of flamingos in the world outside of the wild in sites across the UK. He said: 'These pictures are stunning, I have never seen a flamingo this close before although sadly I guess a hyena must do. 'You really do get the impression of panic in the flock as the hyena starts hunting. 'It takes these birds a little while to get airborne because they need a bit of a run up, sadly for one flamingo it didn't run fast enough. 'These are lesser flamingos which are about a metre tall, but the hyena looks huge compared to the birds, it must have been like a knife slicing through butter when it attacked the flock.' The images are part of a series published in the book 'The Great Rift Valley of East Africa'. http://www.dailymail.co.uk/news/article-1191569/Pictured-The-incredible-moment-hyena-attacks-flock-flamingos.html |
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| Canidae | Jan 9 2012, 08:49 PM Post #29 |
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Omnivore
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Hyena families, O.P'ed by Taipan - In pictures: Family matters to hyenas Page last updated at 09:25 GMT, Tuesday, 2 February 2010       You can get the caption for each of these photos on this website : http://news.bbc.co.uk/2/hi/science/nature/8485653.stm |
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| Canidae | Jan 9 2012, 08:51 PM Post #30 |
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Omnivore
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Hyena communication, O.P'ed by Taipan - Hyena laughs and giggles decoded By Matt Walker Editor, Earth News Page last updated at 01:55 GMT, Tuesday, 30 March 2010 02:55 UK  Hyenas scream for a share The giggling sounds of a hyena contain important information about the animal's status, say scientists. In the first study to decipher the hyena's so-called "laugh", they have shown that the pitch of the giggle reveals a hyena's age. What is more, variations in the frequency of notes used when a hyena makes a noise convey information about the animal's social rank. Details of the US-based research are published in the journal BMC Ecology. Professor Frederic Theunissen from the University of California at Berkeley, US, and Professor Nicolas Mathevon from the Universite Jean Monnet in St Etienne, France, worked with a team of researchers to study 26 captive spotted hyenas held at a field station at Berkeley. There they recorded the animals' calls in various social interactions, such as when the hyenas bickered over food, and established which elements of each call corresponded to other factors. Last year, the researchers published some provisional results from the study. Now they have confirmed that the pitch of the giggle reveals a hyena's age, while variations in the frequency of notes can encode information about dominant and subordinate status. "The hyena's laugh gives receivers cues to assess the social rank of the emitting individual," says Professor Theunissen. "This may allow hyenas to establish feeding rights and organise their food-gathering activities." Spotted hyenas (Crocuta crocuta) are mainly nocturnal, living in clans of between 10 and 90 individuals.  Spotted hyenas make up to 10 different types of vocalisation "Whoops", with long inter-whoop intervals, are primarily used to signal that two individuals have become separated "Grunts" or "soft growls" are emitted when hyenas of the same clan come into close contact Often they hunt cooperatively, but this can generate intense competition as clan mates converge on a kill, fighting over its carcass. However, among spotted hyenas, females dominate, holding a higher rank than all other males, whatever their age. Profs Theunissen and Mathevon's research suggests that the animals convey this status via their laugh or giggle, which they usually make while fighting over food. Previously their sounds had been considered a simple gesture of submission, but the new study has allowed researchers to identify exactly which individual hyena makes each giggle, and the circumstances in which they do so. The information contained within the giggles could be especially important for males new to a clan, as they go immediately to the bottom of the hierarchy when they arrive. Getting to know quickly who is who may give these individuals a better chance of improving their own status. Giggles could also allow hyenas to recruit allies, for instance when one or two hyenas are outnumbered by lions fighting over the same kill. http://news.bbc.co.uk/earth/hi/earth_news/newsid_8593000/8593789.stm |
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