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5-04-2015, 12:54

Modern hyenas

Hunting

There are many accounts and observations of hyena hunting in the ethological literature. One of the most respected observers is Hans Kruuk (2002:104), who described a kill scene he witnessed in the Serengeti:

A pack of spotted hyenas chased a zebra family at night, and by biting at her legs and flanks they manage to slow down one of the mares. The stallion attacks the hyenas but there is little he can do against a dozen of the tormentors, and within minutes of the first bite the mare is down, while the rest of her family runs on. Hyenas tear away the flesh, and more of them join. A total of 34 hyenas eat from the victim, and 40 minutes after being pulled down there is nothing left of the zebra, just a large, dark stain on the grass and a steaming heap of stomach contents. Somewhere a hyena will be chewing on a jaw, reducing it to no more than a set of teeth. But the rest of the prey, including all the large bones, will be digested totally....

Such observations demonstrate that the chance of any prey item landing itself in the fossil record (e. g. by getting neatly piled up in a cave) is extremely slim.

It was Hans Kruuk who first recognized that hyenas live in social groups that he called “clans.” These were composed of up to 100 individuals. They recognized and scent-marked the boundary of their own territory, guarding it from incursions by members of other clans in the vicinity. How might late Pleistocene Siberian humans have recognized

These territorial borders? If a clan were very large, it likely was important to do so. We speculate that it was done by recognition of clan members, the same way we recognize neighborhood dogs or by the experienced eyes of ranchers who can recognize individual beeves even from a great distance. Careful attention to animals and their characteristics, including behavior, is unquestionably a very old human talent as evidenced in the cave art of the European Upper Paleolithic.

Dens

African hyenas make dens by burrowing and enlarging tunnels of other burrowing creatures. When there are natural caves or overhangs for shelter, like their European relatives, they use these also (Brain 1981). These underground dens are spacious enough for even large adult females. Van Lawick and van Lawick-Goodall (1970:108) noted:

Once Demon [a hyena pup] followed Black Angel [an adult female] down one of the dens only to emerge hastily, half hidden in a cloud of dust, as the female started digging.... Black Angel grabbed one pup by the skin of its back and, followed by two other pups, vanished into the den.

Owens and Owens (1984:254-256) provide a brief description of an African brown hyena den:

Star [a female hyena] had enlarged an existing springhare hole for her den. Three deep trenches in the sand led to separate tunnels underground, each concealed by a thicket of acacia bush. During the day she slept in the patchy shade about fifteen yards away. . . [When this den was abandoned and the cubs moved to a new den far away, the Owenses had a chance to explore the den] . . . I crawled head first into the open trench and then into a tunnel about two and a half feet high. By lowering my head and shoulders I could just squeeze inside. . . the tunnel ran straight for about twelve feet and then made a turn to left. . . [wriggling to the end, Della Owens came to a chamber] . . . about five feet in diameter and three feet high... three small tunnels and two larger ones led from the chamber.

Her husband, Mark, was crawling and exploring a similar and connecting tunnel. The den was clean and free of dung. Only a few bones were present. The den was full of fleas, offering the Owenses an explanation, at least in part, why hyena mothers move their cubs to new dens.

Scavenging

The African Wildlife Foundation (2008) comments that species of the African Kalahari hyena possess several adaptations for scavenging. The adaptations are: (1) large and powerful bone-crushing teeth and jaws that enable these creatures to break bones and get to the marrow; (2) they can digest bone - what they cannot fully digest are hair, hooves, and horn; (3) they can travel long distances in search of carrion (their “laughing” vocalization is used to alert other clan members up to three miles away of a food source).

S. M. Cooper (1990:136), in his discussion of hyena scavenging, reports that half of the meals found by hyenas were carrion, and most of these remains were bones. He also reports that during his two-year study in Botswana, herd animals were hunted by the spotted hyena, most frequently zebra foals. Three-quarters of their food came fTom hunting animals that weighed less than 150 kg of consumable mass. J. D. Skinner et al. (1998) report on the number of bones found around two brown hyena maternity dens in theNamib desert. Between 1982 and 1996,14 385 bones had accumulated. This suggests that a fairly large number of the bones excavated in our assemblages were carried in by non-human cave occupants, presumably hyenas. Hyena bone accumulation was the subject of a study by Pickering et al. (2004). These, and other studies, importantly Brain (1981), make us markedly skeptical about who or what deposited bone refuse in archaeological sites where there is evidence of hyena presence.

Growth

L. G. Frank, S. E. Glickman, and P. Licht (1991) report on the unusual prenatal and neonatal behavior of infant hyenas that results from the large titration of testosterone in the female womb. This hormone-rich prenatal environment leads to aggressive behavior in the newborn, of which there are two infants at a given birth. The stronger of the neonates inflicts wounds and even death upon the weaker neonate. This aggression is aided by the fact that newborn hyenas have a full set of teeth at birth. This high titer of testosterone in developing and pregnant females leads to strong masculinization in females, which contributes to their larger body size compared to males, as well as other anatomical features.



 

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