Group-size variation has been examined within a framework of costs and benefits to ecological factors such as food limitations and risks from predators. Social interactions between males from male–male competition might also influence group size particularly in polygynous males. To explore the role of social and ecological factors on group size outside the mating season I examined the influence of abundance on male grouping patterns in a population of Roosevelt elk (Cervus elaphus roosevelti) in northwestern California, USA. Male grouping patterns were complex, males often group with other males, but they also can be transient members of female groups. Because male–male competition is pervasive even outside of the mating season, sizes of groups comprised of males only should be positive and linearly related to abundance of the male population or frequency associated. Whereas the number of males in female groups should be inversely related to female abundance or density associated. Males associating with females is more likely at low female abundance because females might still be reproductively active and per capita forage should be abundant. Across a 23-year study I examined whether male or female abundance was related to male only group sizes and the number of males in female groups. Size of male-only groups displayed a positive, linear relationship with male abundance and the number of males in female groups exhibited an inverse, linear relationship with female abundance. Uncovering forces influencing male grouping patterns required using the appropriate metric of abundance. Social factors likely influenced sizes of male-only groups and ecological factors probably influenced male prevalence in female groups.

中文翻译：

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雄性罗斯福麋鹿的频率和密度相关分组模式

已经在生态因素的成本和收益框架内检查了群体规模的变化，例如食物限制和来自捕食者的风险。来自男性-男性竞争的男性之间的社会互动也可能影响群体规模，尤其是在一夫多妻的男性中。为了探索交配季节之外的社会和生态因素对群体规模的作用，我研究了丰度对美国加利福尼亚州西北部罗斯福麋鹿（Cervus elaphus roosevelti）种群雄性分组模式的影响。男性分组模式复杂，男性经常与其他男性分组，但他们也可以是女性群体的临时成员。因为即使在交配季节之外，雄性之间的竞争也很普遍，仅由男性组成的群体的规模应该是正的，并且与男性人口的丰度或相关频率呈线性相关。而女性群体中男性的数量应该与相关的女性丰度或密度成反比。在雌性丰度较低的情况下，雄性与雌性交往的可能性更大，因为雌性可能仍处于繁殖期，人均草料应该充足。在一项为期 23 年的研究中，我检查了男性或女性的丰度是否与仅限男性的群体规模和女性群体中的男性人数有关。仅男性群体的规模与男性丰度呈正线性关系，女性群体中男性数量与女性丰度呈负线性关系。需要使用适当的丰度指标来揭示影响男性分组模式的力量。社会因素可能影响男性群体的规模，生态因素可能影响女性群体中的男性患病率。