Interspecific resource partitioning in sympatric ursids
Interspecific resource partitioning in sympatric ursids
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DOI：
10.1890/1051-0761(2006)016
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发表时间：
2006-12-01
影响因子：
5
通讯作者：
Adam, Layne G.
中科院分区：
文献类型：
--
作者：
Belant, Jerrold L.;Kielland, Knut;Adam, Layne G.
一个物种的基本生态位很少实现，因为其他物种的存在将其限制在较窄的生态条件范围内。这一范围较窄的条件的影响定义了资源的划分方式。资源分配已被推断，但没有证明以前同域的熊类。我们估计了同域棕熊（Ursus arctos）和美国黑熊（U。1998年至2000年，阿拉斯加中南部。根据对鲑爪血液和角蛋白的同位素分析，鲑爪（Oncorhynchus spp.）在棕熊的饮食中占主导地位（每年> 53%），而黑熊每年吸收0-25%的鲑鱼。黑熊在产卵数量低于平均水平的一年中没有利用鲑鱼，可能是因为棕熊阻止黑熊接近鲑鱼。鲑鱼的比例同化饮食是一致的，多年来棕熊和代表他们的饮食的主要部分。在研究区域的棕熊的身体大小接近几个沿海棕熊种群的平均身体大小，证明鲑鱼的可用性身体状况的重要性。黑熊发生在一个相当的密度（质量：质量），但身体状况不同，直接关系到鲑鱼同化在他们的饮食。这两个物种在春季获得最瘦的体重和所有的身体脂肪在夏季时，鲑鱼。改善身体状况（即，增加身体脂肪的百分比）减少了冬眠期间瘦体重的增加，导致第二年春天身体状况更好。此外，黑熊繁殖与身体状况直接相关;当身体状况较低时，繁殖率会降低。多年来棕熊的高体脂含量反映在持续的高繁殖水平上。我们认为，黑熊的基本生态位的限制棕熊通过划分的食物资源，这在不同年份。减少对鲑鱼的开发导致黑熊更广泛地依赖不太可靠或营养的食物来源（例如，驼鹿[Alces alces]，浆果）导致身体状况下降和随后的繁殖。
The fundamental niche of a species is rarely if ever realized because the presence of other species restricts it to a narrower range of ecological conditions. The effects of this narrower range of conditions define how resources are partitioned. Resource partitioning has been inferred but not demonstrated previously for sympatric ursids. We estimated assimilated diet in relation to body condition (body fat and lean and total body mass) and reproduction for sympatric brown bears (Ursus arctos) and American black bears (U. americanus) in southcentral Alaska, 1998-2000. Based on isotopic analysis of blood and keratin in claws, salmon (Oncorhynchus spp.) predominated in brown bear diets (> 53% annually) whereas black bears assimilated 0-25% salmon annually. Black bears did not exploit salmon during a year with below average spawning numbers, probably because brown bears deterred black bear access to salmon. Proportion of salmon in assimilated diet was consistent across years for brown bears and represented the major portion of their diet. Body size of brown bears in the study area approached mean body size of several coastal brown bear populations, demonstrating the importance of salmon availability to body condition. Black bears occurred at a comparable density (mass: mass), but body condition varied and was related directly to the amount of salmon assimilated in their diet. Both species gained most lean body mass during spring and all body fat during summer when salmon were present. Improved body condition (i.e., increased percentage body fat) from salmon consumption reduced catabolism of lean body mass during hibernation, resulting in better body condition the following spring. Further, black bear reproduction was directly related to body condition; reproductive rates were reduced when body condition was lower. High body fat content across years for brown bears was reflected in consistently high reproductive levels. We suggest that the fundamental niche of black bears was constrained by brown bears through partitioning of food resources, which varied among years. Reduced exploitation of salmon caused black bears to rely more extensively on less reliable or nutritious food sources (e.g., moose [Alces alces], berries) resulting in lowered body condition and subsequent reproduction.