Abstract We present the results of a 5-yr field study on colony dynamics and plant community associations of Owyhee harvester ants, Pogonomyrmex salinus (Olsen), in sagebrush-steppe habitat in southwestern Idaho. Over a 5-yr period, the total number of ant colonies across 16 sites increased from 843 to 878 (4.15%) as a result of 315 colony deaths and 350 colony initiations. Up to 7.1% of colony initiations may have been instances of nest relocation. Colonies had a higher rate of failure in their first year than in subsequent years (12.4 vs 4.6–8.4% over the next 3 yr). Of the 11 sites analyzed for colony dispersion, one was significantly clumped and the others did not differ from random. Population density in the final year of study ranged from 0.1 to 62.9 colonies/ha and was best described by an inverse relationship with sagebrush cover and positive relationship with coverage of non-Bromus (non-cheatgrass) understory vegetation. We interpret these results both in terms of 1) food resources—harvester ants avoid cheatgrass seeds in their diet, preferring instead small-seeded grasses and forbs, and 2) habitat structure—harvester ants prefer nesting in open areas where the ground is exposed to sun and they can clear vegetation from the vicinity of their nests. Given the habitat associations we report, the transition from sagebrush-dominated habitat to open grasslands that is occurring rapidly throughout much of the western United States may prove costly to native plant species whose seeds are readily consumed by harvester ants.

中文翻译：

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鼠尾草-草原栖息地中收获蚁、Pogonomyrmex salinus（膜翅目：蚁科）的群落动态和植物群落关联

摘要 我们介绍了一项为期 5 年的田间研究结果，该研究对爱达荷州西南部山艾树草原栖息地中 Owyhee 收获蚁 Pogonomyrmex salinus (Olsen) 的群体动态和植物群落关联进行了研究。在 5 年的时间里，由于 315 个蚁群死亡和 350 个蚁群启动，16 个地点的蚁群总数从 843 个增加到 878 个（4.15%）。高达 7.1% 的殖民地开始可能是巢重新安置的实例。殖民地在第一年的失败率高于随后几年（接下来 3 年为 12.4% vs 4.6-8.4%）。在分析菌落分散的 11 个位点中，一个显着聚集，其他与随机没有区别。研究最后一年的人口密度从 0.1 到 62 不等。9 菌落/公顷，最好通过与山艾树覆盖率的反比关系和与非 Bromus（非作弊草）林下植被覆盖率的正相关关系来描述。我们从以下两个方面来解释这些结果：1) 食物资源——收割蚂蚁在它们的饮食中避免使用欺骗草种子，而是更喜欢小种子的草和杂草，以及 2) 栖息地结构——收割蚂蚁更喜欢在地面暴露的开放区域筑巢它们可以清除巢穴附近的植被。鉴于我们报告的栖息地协会，从山艾树占主导地位的栖息地过渡到美国西部大部分地区迅速发生的开阔草原，对于种子很容易被收获蚁食用的本地植物物种来说可能是代价高昂的。