Implications of a high-energy and low-protein diet on the body composition, fitness, and competitive abilities of black (Ursus americanus) and grizzly (Ursus arctos) bears
Implications of a high-energy and low-protein diet on the body composition, fitness, and competitive abilities of black (Ursus americanus) and grizzly (Ursus arctos) bears
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DOI：
10.1139/z11-026
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发表时间：
2011-06-01
影响因子：
1.4
通讯作者：
McLellan, B. N.
中科院分区：
文献类型：
--
作者：
McLellan, B. N.
对于熊来说，植物不是理想的食物，但许多种群基本上是素食者。这种饮食对黑熊(Ursus americanus Pallas，1780)和灰熊(Ursus arctos L.，1758)的身体成分、健康和竞争能力的影响进行了有限的实地调查。对来自不列颠哥伦比亚省平头山谷的灰熊和黑熊的分析表明，不同物种之间的饮食存在季节性差异，但这两种物种夏季饮食的85%是蛋白质含量较低的水果。身体成分测量显示，熊在春天脂肪减少，夏天脂肪增加，灰熊比黑熊更瘦。个体黑熊的体重增加速度比理论预测快2.7倍。熊在吃水果时迅速增加了脂肪，但失去了瘦组织，这表明瘦组织被用来缓冲季节性蛋白质短缺。对不吃鲑鱼的灰熊种群进行比较发现，食物中的肉量与成年雌性体重呈正相关，而与熊密度呈负相关。熊具有行为和表型的可塑性，这使得以植物为食的种群拥有较小但肥胖的雌性，并且比更专注于获取陆生肉类的种群生活在更高的密度。
Plants are not ideal foods for bears yet many populations are largely vegetarian. Implications of this diet on the body composition, fitness, and competiveness of black (Ursus americanus Pallas, 1780) and grizzly (Ursus arctos L., 1758) bears have had limited field investigation. The analysis of scats of grizzly and black bears from the Flathead valley, British Columbia, suggest seasonal dietary differences between species, but >85% of the summer diet of both species were fruits that are low in protein. Body composition measurements showed bears loose fat during spring, gained fat during summer, and grizzly bears were leaner than black bears. Individual black bears gained mass up to 2.7 times faster than theory predicted. Bears rapidly gained fat but lost lean tissues while feeding on fruit, suggesting that lean tissues were used to buffer seasonal protein shortages. Comparisons among populations of grizzly bears without access to salmon revealed the amount of meat in the diet was positively related with adult female mass but negatively related with bear density. Bears have the behavioural and phenotypic plasticity which enables populations that focus their foraging on plants to have small but fat females and live at higher densities than populations that focus more on obtaining terrestrial meat.