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Post by grrraaahhh on Mar 17, 2011 13:50:11 GMT -9
The data on black bears is surprising and interesting: Abstract During observational fieldwork in undisturbed ranges of free-roaming bison and moose, I have identified approximately 8% of surface bones as spirally or green-fractured due to documented carnivore activity, and 5% as spirally or green-fractured due to trampling or dust wallowing by bison. The bones of smaller species suffer up to 50% breakage. Bone modifications by wild wolves and bears are briefly described, as are characteristics of fractures caused by trampling and wallowing. Table 1 presents data on sites investigated in the fieldwork, and Table 2 presents data on bone-feeding experiments involving captive animals at the National Zoological Park in Washington, D.C. Complete descriptions of the experiments are in Haynes (1981). The purpose of the experiments was to allow formulation of bone-gnawing models and to document end-effects of gnawing by large cats, bears, hyenas, and canids. Data in the two tables provide the base for synoptic discussions below.  Note: Table 1 did not have any bear data hence its omission. Scavenging by BearsBears actively scavenge carcasses in spring and fall. Like other species of scavenger, bears prefer to eat meat, hide, viscera, or cartilage before finally gnawing bones. Black bears occasionally fracture long bones of adult bison, but do so more often because wolves have first gnawed off an epiphysis (usually the distal end of femora, the proximal end of humeri, or the proximal end of tibiae). While large bears are capable of breaking bison limb bones, it hardly seems adaptive for them to rely on such a difficult source of food. However, in years when there have been poor crops of berries or mast, bears would make stronger efforts to feed on all available carcass parts in the fall, and many long bones would be broken to get out marrow. Winter scavenging would also be heavy by bears in years when summer and fall foods were in poor supply. Haynes, G. 1981, FREQUENCIES OF SPIRAL AND GREEN-BONE FRACTURES. ON UNGULATE LIMLB BONES.PDF LINK: www.google.com/url?q=http://www.unr.edu/anthropology/people/faculty/haynes/download%2520Haynes_Spiral%2520fractures_%2520AmerAnt.pdf&sa=U&ei=D1-CTYyNN4W6sAPTxaz5AQ&ved=0CA0QFjAA&usg=AFQjCNEiA7LaxAj73PiJsCM1AxTL4iFkng |
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Post by grrraaahhh on Mar 17, 2011 13:55:58 GMT -9
More from Haynes..... Abstract.— Large cats, canids, bears, and hyenas create distinctive types of damage when they gnaw bones. This paper describes the diagnostic characteristics of damage done by each taxon to femora and tibiae of herbivores whose body weights are 300 kg or more. Pleistocene and Recent fossil collections that include gnawed bones might provide data on the presence of carnivores whose own remains are not found in the collections. Information might also be gained about predator and scavenger utilization of prey carcasses, often a reflection of prey vulnerability or availability in past communities.Bears (Ursus arctos, U. americanus mainly; other species listed in Table 1).—Bear gnaw damage to large bovid femora: Most bears will usually not gnaw heavily on bones after the soft tissue has dried or been removed, although there are wide behavioral differences between individuals and species. Damage from bear gnawing is distinct from damage caused by canids and hyenas, in that the broader cheek teeth of bears grind down and crush cancellous bone as well as plane or shear it off. However, bear gnawing, like hyena or wolf gnawing, may leave distinct furrows or score marks across cancellous tissue. In the early stages the cheek teeth grind off most of the greater trochanter and the larger trochlear rim, with the jaws aligned parallel to the rims. In the later stages the stump of the greater trochanter is faceted or flattened, and the exposed cancellous bone may be gouged into fewer than 5 pits that are 6 mm deep and 10-20 mm long, each corresponding to and about the size of individual cheek teeth of large bears. There is rarely a rim of compact bone higher than the cancellous bone of the trochanter stump. The trochlear rims also appear to have been crushed or ground off between teeth, rather than chopped off. There may be no tooth marks or scratches on the shaft surfaces. The occasional tooth marks on compact bone appear as short and wide sets of parallel scrapes, each seldom wider than 1.5 mm or longer than 9 mm, or they may appear as roughly circular pits no deeper than 0.5 mm. Bear gnaw damage to large bovid tibiae: Black and brown bears (U. americanus and U. arctos) do not often severely damage tibiae of large herbivores such as Bison bison unless wolves have first gnawed off epiphyses. Bears seldom inflict the full range of damage of which they are capable, except when other sources of food are in short supply.  Typical damage due to gnawing by bears appears as a rounding of edges and a grinding with crushing of compact bone surfaces, exposing cancellous tissue and leaving it with a mashed look. There may be occasional tooth cusp impressions in the proximal end of the bone, consisting of single, nearly flat-bottomed holes entering cancellous tissue. There may also be sets of parallel furrows on the crest, resulting from the filing away of bone by separate tubercles on the cheek teeth. The cheek teeth may produce a few short scratches on the shaft. These scratches actually appear similar to rodent gnaw marks: short and parallel, shallowly etched, straight score lines.   Haynes, G. 1983, A guide for differentiating mammalian carnivore taxa responsible for gnaw damage to herbivore limb bones.PDF Link: www.google.com/url?q=http://www.unr.edu/anthropology/people/faculty/haynes/download%2520Haynes_Paleobiol83.pdf&sa=U&ei=_mKCTb_8BIr0tgPip-j1AQ&ved=0CA4QFjAA&usg=AFQjCNFTq7dALY_5imJzqYPqw8esLX3_fw |
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Post by grrraaahhh on Mar 17, 2011 13:57:44 GMT -9
More from Haynes..... Abstract.— Large cats, canids, bears, and hyenas create distinctive types of damage when they gnaw bones. This paper describes the diagnostic characteristics of damage done by each taxon to femora and tibiae of herbivores whose body weights are 300 kg or more. Pleistocene and Recent fossil collections that include gnawed bones might provide data on the presence of carnivores whose own remains are not found in the collections. Information might also be gained about predator and scavenger utilization of prey carcasses, often a reflection of prey vulnerability or availability in past communities.Bears (Ursus arctos, U. americanus mainly; other species listed in Table 1).—Bear gnaw damage to large bovid femora: Most bears will usually not gnaw heavily on bones after the soft tissue has dried or been removed, although there are wide behavioral differences between individuals and species. Damage from bear gnawing is distinct from damage caused by canids and hyenas, in that the broader cheek teeth of bears grind down and crush cancellous bone as well as plane or shear it off. However, bear gnawing, like hyena or wolf gnawing, may leave distinct furrows or score marks across cancellous tissue. In the early stages the cheek teeth grind off most of the greater trochanter and the larger trochlear rim, with the jaws aligned parallel to the rims. In the later stages the stump of the greater trochanter is faceted or flattened, and the exposed cancellous bone may be gouged into fewer than 5 pits that are 6 mm deep and 10-20 mm long, each corresponding to and about the size of individual cheek teeth of large bears. There is rarely a rim of compact bone higher than the cancellous bone of the trochanter stump. The trochlear rims also appear to have been crushed or ground off between teeth, rather than chopped off. There may be no tooth marks or scratches on the shaft surfaces. The occasional tooth marks on compact bone appear as short and wide sets of parallel scrapes, each seldom wider than 1.5 mm or longer than 9 mm, or they may appear as roughly circular pits no deeper than 0.5 mm. Bear gnaw damage to large bovid tibiae: Black and brown bears (U. americanus and U. arctos) do not often severely damage tibiae of large herbivores such as Bison bison unless wolves have first gnawed off epiphyses. Bears seldom inflict the full range of damage of which they are capable, except when other sources of food are in short supply. Typical damage due to gnawing by bears appears as a rounding of edges and a grinding with crushing of compact bone surfaces, exposing cancellous tissue and leaving it with a mashed look. There may be occasional tooth cusp impressions in the proximal end of the bone, consisting of single, nearly flat-bottomed holes entering cancellous tissue. There may also be sets of parallel furrows on the crest, resulting from the filing away of bone by separate tubercles on the cheek teeth. The cheek teeth may produce a few short scratches on the shaft. These scratches actually appear similar to rodent gnaw marks: short and parallel, shallowly etched, straight score lines. Haynes, G. 1983, A guide for differentiating mammalian carnivore taxa responsible for gnaw damage to herbivore limb bones.PDF Link: www.google.com/url?q=http://www.unr.edu/anthropology/people/faculty/haynes/download%2520Haynes_Paleobiol83.pdf&sa=U&ei=_mKCTb_8BIr0tgPip-j1AQ&ved=0CA4QFjAA&usg=AFQjCNFTq7dALY_5imJzqYPqw8esLX3_fwHaynes (1983) follow up for those people interested in big cat comparisons. Lion, tiger, and jaguar (Panthera leo, P. ti-gris, and P. onca).—Large cat gnaw damage to large bovid femora: African lions, Bengal tigers, and jaguars will not often sustain gnawing on large bones, although captive cubs and adults may mouth bones and gnaw briefly from time to time. The main damage from large cats consists of the biting off of the greater trochanter, undercut biting of the femoral head, and scraping off of trochlear rims by use of the carnassials and other cheek teeth, leaving a few, relatively deep, identifiable grooves from individual tooth cusps running perpendicular to the larger trochlear rim. The grooves, if clearly produced, will usually be larger than grooves created by the teeth of hyenas or wolves, and may be fewer in number. Lion cubs may gouge out only some of the greater trochanter, leaving a discontinuous 3-7-mm-high rim of compact tissue around the internal cancellous tissue, similar to gnaw damage created by adult wolves. Adult lions sometimes leave tooth scratches on the compact tissue of the diaphysis. Most of these marks are nearly perpendicular to the element's long axis, and all are shallow but rather sharply incised. The outline of the greater trochanter may be irregularly gnawed into deep round pits. The basic identifying characteristic of large cat gnawing is the rough and irregular marking left by biting on or through cancellous bone of the epiphyses. These marks are wide, deep, and countable, and are inflicted by the large cheek teeth. The main damage that I have recorded from large cats gnawing on tibiae has been moderately deep and isolated scoring of parts of the proximal articular edges on medial and lateral sides. The cranial proximal end (or "crest") is also occasionally furrowed perpendicular to the element's long axis, probably during consumption of the muscle and soft tissue around the patella. The crest may also be bitten off. From Chapter 19 (Seryodkin): Медведи съедают добычу практически целиком, вплоть до крупных костей, которые не едят тигры. Тигры часто оставляют скелет, шкуру, целую голову, мясо на нижних частях конечностей и шее (Kerley et al., 2002). Медведи от крупного животного чаще всего оставляют частично разгрызенные кости конечностей, верхние и нижние челюсти, часть позвонков; иногда кости таза, лопатки и рёбра. При нехватке кормов, особенно ранней весной, медведи утилизируют тушу более полно. Медведь-шатун съедает животных полностью, включая все кости (Костоглод, 1976). Bears eat prey almost entirely up to the major bones, which do not eat tigers. Tigers often leave a skeleton, skin, a head, the meat in the lower extremities and neck (Kerley et al., 2002). Bears on a large animal often left partially razgryzennye limb bones, upper and lower jaw, some vertebrae, and sometimes the bones of the pelvis, scapula and ribs. With a shortage of fodder, especially in early spring, bears utilize more fully the carcass. Bear rod eats animal completely, including all of the bones (Kostoglod, 1976). Seryodkin, Ivan (2006). The ecology, behavior, management and conservation status of brown bears in Sikhote-Alin (Russian). Far Eastern National University, Vladivostok, Russia. pp. 1–252. Also.... Если медведь найдет падаль или добудет крупное животное, он временно переходит на мясную пищу. В этом случае фекальные массы приобретают черный цвет и изобилуют осколками крупных костей, шерстью, поэтому помет не— крупного медведя в таком случае можно принять за помет волка. If a bear finds carrion or will produce a large animal, he temporarily moves (cache) the meat. In this case, fecal masses become black and full of fragments of large bones, hair, droppings, so the large bear in this case can be taken for a litter of wolf. www.piterhunt.ru/Library/rukovskiy/po_sledam_lesnih_zverey/6.htm |
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Post by grrraaahhh on Mar 18, 2011 8:10:34 GMT -9
 Above: dental hygiene practice [sic] by captive Manchurian brown bear. |
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Post by grrraaahhh on Mar 20, 2011 19:07:50 GMT -9
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Post by grrraaahhh on Aug 19, 2011 14:49:36 GMT -9
Nice to see more follow up studies (see reply # 1 & # 2) .... AbstractActualism has been a fundamental tool in taphonomy. The knowledge of accumulation patterning of modern faunal allows us to interpret the activity of different actors in the archaeological record and to reconstruct the behaviour of preterit animals and humans in which we are interested. However, until now, there are few works that include bone modifications made by bears amongst those made by carnivores. Most data about bone modifications made by bears have been obtained from the archaeo-palaeontological record. In most of these assemblages, the presence of bears is related to their period of hibernation. Therefore, in these contexts, the changes documented on recovered bear bones are associated only with cannibalism. In this paper, we present an actualistic study about modifications on bones made by modern brown bears. These animals can cause damage similar to those produced by other large carnivores. Generally, bear activity leaves slight damage, mainly on large-sized animal bones. However, on bones of small-sized animals and those of greater fragility, the bears can produce abundant damage. Though not usual, bears can break long bones and consume the complete epiphysis. This study suggests that bears have the potential to be agents of bone modification in fossil assemblages. Consequently, they should be considered as a possible agent of modification of faunal remains in the fossil record. Saladié, P., Huguet, R., Díez, C., Rodríguez-Hidalgo, A. and Carbonell, E. (2011), Taphonomic modifications produced by modern brown bears (Ursus arctos). International Journal of Osteoarchaeology. onlinelibrary.wiley.com/doi/10.1002/oa.1237/abstractMore follow up article details to come..... |
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