Abstract Global change threatens the persistence of multiple taxonomic groups, including butterflies. While conservation efforts for butterfly populations have increased, they are often hampered by a lack of true density estimates and a better understanding of ecological factors that influence density. Our objective was to enhance current grassland butterfly conservation efforts by using line-transect distance sampling to calculate density estimates and model the influence of landscape and local variables on butterfly density in the Northern Great Plains, USA. We calculated density for five obligate and ten facultative grassland species to produce one of the most extensive datasets for butterfly densities to date. In contrast to most previous research, we found that landscape variables influenced butterfly density more often than local variables. Specifically, the percent cover of perennial grasslands, crop lands, and wetlands appeared in 90% of species models, whereas common local variables—forb richness and invasive plant cover— appeared in 60% of best-ranked models. We expected the density of obligate butterfly species to decrease as invasive plants increased, but butterfly species' responses varied with larval diet, instead of habitat associations. Best-ranked models for Danaus plexippus and Speyeria idalia, two species of conservation concern with obligate host plants, did not include local host plant availability. Our results reiterate the importance of modeling species responses to variables across multiple scales and the potential benefits of conserving large tracts of grasslands. Although results emphasize the need for conservation at the landscape scale, managing for heterogeneous local scale variables will also help conserve grassland butterflies.

中文翻译：

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农业生态系统草地蝴蝶保护的多尺度考虑

摘要 全球变化威胁着包括蝴蝶在内的多种分类群的持续存在。虽然蝴蝶种群的保护工作有所增加，但它们往往受到缺乏真实密度估计和对影响密度的生态因素的更好理解的阻碍。我们的目标是通过使用线样距离采样来计算密度估计值并模拟景观和局部变量对美国北部大平原蝴蝶密度的影响，从而加强当前的草原蝴蝶保护工作。我们计算了五种专性和十种兼性草原物种的密度，以生成迄今为止最广泛的蝴蝶密度数据集之一。与之前的大多数研究相比，我们发现景观变量比局部变量更常影响蝴蝶密度。具体来说，多年生草地、农田和湿地的覆盖百分比出现在 90% 的物种模型中，而常见的局部变量——森林丰富度和入侵植物覆盖——出现在 60% 的最佳模型中。我们预计专性蝴蝶物种的密度会随着入侵植物的增加而减少，但蝴蝶物种的反应因幼虫饮食而异，而不是栖息地关联。Danaus plexippus 和 Speyeria idalia 的排名最高的模型是两种具有专性寄主植物的保护问题，不包括当地寄主植物的可用性。我们的结果重申了模拟物种对跨多个尺度的变量响应的重要性以及保护大片草原的潜在好处。尽管结果强调了在景观尺度上进行保护的必要性，