Bears foraging near human developments are often presumed to be responding to food shortage, but this explanation ignores social factors, in particular despotism in bears. We analyzed the age distribution and body condition index (BCI) of shot brown bears in relation to densities of bears and people, and whether the shot bears were killed by managers (i.e., problem bears; n = 149), in self‐defense (n = 51), or were hunter‐killed nonproblem bears (n = 1,896) during 1990–2010. We compared patterns between areas with (Slovenia) and without supplemental feeding (Sweden) of bears relative to 2 hypotheses. The food‐search/food‐competition hypothesis predicts that problem bears should have a higher BCI (e.g., exploiting easily accessible and/or nutritious human‐derived foods) or lower BCI (e.g., because of food shortage) than nonproblem bears, that BCI and human density should have a positive correlation, and problem bear occurrence and seasonal mean BCI of nonproblem bears should have a negative correlation (i.e., more problem bears during years of low food availability). Food competition among bears additionally predicts an inverse relationship between BCI and bear density. The safety‐search/naivety hypothesis (i.e., avoiding other bears or lack of human experience) predicts no relationship between BCI and human density, provided no dietary differences due to spatiotemporal habitat use among bears, no relationship between problem bear occurrence and seasonal mean BCI of nonproblem bears, and does not necessarily predict a difference between BCI for problem/nonproblem bears. If food competition or predation avoidance explained bear occurrence near settlements, we predicted younger problem than nonproblem bears and a negative correlation between age and human density. However, if only food search explained bear occurrence near settlements, we predicted no relation between age and problem or nonproblem bear status, or between age and human density. We found no difference in BCI or its variability between problem and nonproblem bears, no relation between BCI and human density, and no correlation between numbers of problem bears shot and seasonal mean BCI for either country. The peak of shot problem bears occurred from April to June in Slovenia and in June in Sweden (i.e., during the mating period when most intraspecific predation occurs and before fall hyperphagia). Problem bears were younger than nonproblem bears, and both problem and nonproblem bears were younger in areas of higher human density. These age differences, in combination with similarities in BCI between problem and nonproblem bears and lack of correlation between BCI and human density, suggested safety‐search and naïve dispersal to be the primary mechanisms responsible for bear occurrence near settlements. Younger bears are less competitive, more vulnerable to intraspecific predation, and lack human experience, compared to adults. Body condition was inversely related to the bear density index in Sweden, whereas we found no correlation in Slovenia, suggesting that supplemental feeding may have reduced food competition, in combination with high bear harvest rates. Bears shot in self‐defense were older and their BCI did not differ from that of nonproblem bears. Reasons other than food shortage apparently explained why most bears were involved in encounters with people or viewed as problematic near settlements in our study. © 2014 The Wildlife Society.

中文翻译：

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专制行为或食物搜寻可以解释欧洲棕熊问题的发生吗？


人们通常认为，熊在人类发展区附近觅食是为了应对食物短缺，但这种解释忽视了社会因素，尤其是熊的专制主义。我们分析了被射杀棕熊的年龄分布和身体状况指数（BCI）与熊和人的密度之间的关系，以及被射杀的棕熊是否被管理者杀死（即问题熊； n = 149），出于自卫（ n = 51），或者在 1990 年至 2010 年期间被猎人杀死的非问题熊（ n = 1,896）。我们根据两种假设比较了有熊补充喂养的地区（斯洛文尼亚）和没有补充喂养的地区（瑞典）之间的模式。食物搜索/食物竞争假说预测，问题熊应该比非问题熊有更高的 BCI（例如，利用容易获得和/或有营养的人类食品）或更低的 BCI（例如，因为食物短缺），即 BCI与人类密度应呈正相关，问题熊的发生率与非问题熊的季节性平均 BCI 应呈负相关（即，在食物供应不足的年份，问题熊数量较多）。熊之间的食物竞争还预测 BCI 与熊密度之间存在反比关系。安全搜索/天真假说（即避开其他熊或缺乏人类经验）预测 BCI 与人类密度之间没有关系，前提是熊之间的时空栖息地使用不存在饮食差异，问题熊的发生率与季节性平均 BCI 之间没有关系的非问题熊的 BCI，并且不一定预测问题/非问题熊的 BCI 之间的差异。 如果食物竞争或避免捕食解释了定居点附近熊的出现，我们预测问题熊比非问题熊更年轻，并且年龄与人口密度之间呈负相关。然而，如果仅靠食物搜索来解释定居点附近熊的出现，我们就预测年龄与问题或非问题熊状况之间或年龄与人口密度之间没有关系。我们发现问题熊和非问题熊之间的 BCI 或其变异性没有差异，BCI 与人口密度之间没有关系，并且两个国家被射杀的问题熊数量与季节平均 BCI 之间没有相关性。斯洛文尼亚的射杀问题熊的高峰发生在四月到六月，瑞典的六月是（即在大多数种内捕食发生的交配期和秋季进食过多之前）。问题熊比非问题熊更年轻，而且在人口密度较高的地区，问题熊和非问题熊都更年轻。这些年龄差异，加上问题熊和非问题熊之间 BCI 的相似性，以及 BCI 和人类密度之间缺乏相关性，表明安全搜索和幼稚分散是导致定居点附近出现熊的主要机制。与成年熊相比，年幼的熊竞争力较差，更容易受到种内捕食，并且缺乏人类经验。在瑞典，身体状况与熊的密度指数呈负相关，而我们在斯洛文尼亚发现没有相关性，这表明补充喂养可能减少了食物竞争，同时熊的收获率很高。因自卫而被射杀的熊年龄较大，其脑机接口与没有问题的熊没有区别。 在我们的研究中，除了食物短缺之外的其他原因显然解释了为什么大多数熊会与人类发生接触，或者在定居点附近被视为有问题。 © 2014 野生动物协会。