Bear Size ~

[brotherbear]

http://shaggygod.proboards.com/   -    First posted by grraahh.
 
"A vegetative diet alone is not a sufficient stimulus to produce large size, as is illustrated by several successful taxa of small mammals. Small animals are more vulnerable to predation than are large ones so they need to remain adjacent to escape habitat such as holes in the ground, trees, or thick vegetation. To survive in open habitat, a mammal must be able to defend itself from predators or be fast enough to escape them. Consequently, as the body size of some bear species increased, they probably occupied more open habitat for longer periods, and were able to increase the proportion of vegetation in the diet. Their larger size also made them better able to defend themselves from predators. As the diet became progressively more vegetative, there would have been continuing pressure for body size to increase so enough vegetation could be ingested and processed to substitute for a high quality diet of animal material. Larger body size also made it possible to travel more in search of patchy food resources and to store and carry more fat with which to survive during periods of seasonal or unpredictable food shortage. With increased body size and well-developed canines, some bears were able to kill ungulates and other mammals, defend carrion from competitors, and protect themselves from other predators. Through this unique combination of being able to be predators, scavengers, and herbivores, they were able to exploit several food bases."

"Small predators are restricted to small prey, so that one benefit of being large is that an animal can kill both small and large prey (Gittleman 1985). For example, brown bears are capable of taking advantage of relatively small animals such as ground squirrels and salmon in circumstances where their abundance makes such behavior energetically or nutritionally worthwhile (e.g., Stonorov and Stokes 1972, Murie 1981). Even so, the ratio between the size of the bear and its prey may be misleading since the predator's large size may be necessary to move heavy stones or earth to catch ground squirrels or to stay warm while standing in cold water for protracted periods while fishing for salmon. In the case of the more carnivorous bear species, their maximum size may have been influenced by the maximum size of generally available prey. Reply