The pygmy rabbit (Brachylagus idahoensis) is endemic to the sagebrush steppe landscapes in the western United States. Pygmy rabbits have adapted to this region by depending on big sagebrush (Artemisia tridentata) as a source of nutrition and concealment from predators. Being a central place forager, and a dietary specialist makes pygmy rabbits an ideal subject to study foraging tradeoffs. Our objectives were to determine if pygmy rabbit foraging patterns are influenced by the nutrient content of individual sagebrush, or the size and location of individual sagebrush. We first developed a near infrared spectroscopy assay that can be conducted in the field, with whole plant foliage, to determine individual sagebrush crude protein (CP) and acid detergent fiber (ADF) contents. We then measured the size, location, protein, and fiber contents of >1,500 foraged and non‐foraged sagebrush plants surrounding pygmy rabbit burrows in 2 field sites in northern Utah, USA. We found significant site differences in sagebrush CP levels and significant season differences in sagebrush ADF levels; sagebrush closer to central burrows were higher in protein and lower in fiber. Pygmy rabbits preferred to forage on taller sagebrush plants that were closer to the central burrow but only marginally higher in CP (0.2%) and lower in ADF (1%). Sagebrush plants with a >50% chance of being foraged, were <5.6 m from the burrow, >0.67 m tall, >10.4% CP, and <34.95% ADF. The selection of closer, larger, and more nutrient‐dense sagebrush may be influenced by pygmy rabbits' need for concealment from predators or a way to minimize foraging effort. © 2020 The Wildlife Society.

中文翻译：

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鼠尾草特性影响侏儒兔的觅食方式

侏儒兔（Brachylagus idahoensis）在美国西部是鼠尾草草原的特有物种。矮小兔依靠大鼠尾草（Artemisia tridentata）作为掠食者的营养和隐藏来源。作为觅食者的主要场所，并且饮食专家使侏儒兔成为研究觅食权衡的理想对象。我们的目标是确定侏儒兔的觅食方式是否受到单个鼠尾草的营养成分或单个鼠尾草的大小和位置的影响。我们首先开发了一种近红外光谱测定法，该测定法可在田间使用整个植物的叶子进行测定，以测定鼠尾草粗蛋白（CP）和酸性洗涤剂纤维（ADF）的含量。然后，我们在美国犹他州北部的2个田地中，对侏儒兔洞周围的1,500余株觅食和未觅食的鼠尾草植物进行了大小，位置，蛋白质和纤维含量的测量。我们发现鼠尾草CP水平存在明显的站点差异，而鼠尾草ADF水平存在明显的季节差异。靠近中央洞穴的鼠尾草的蛋白质含量较高，而纤维含量较低。y格米兔更喜欢在较高的鼠尾草植物上觅食，这些植物靠近中央洞穴，但CP的含量略高（0.2％），ADF的含量低（1％）。鼠尾草的觅食机会> 50％，距洞穴<5.6 m，高度> 0.67 m，CP> 10.4％，ADF <34.95％。矮小兔子对躲避捕食者的需求或减少觅食努力的方法可能会影响选择更近，更大和更富营养的鼠尾草。©2020野生动物协会。y格米兔更喜欢在较高的鼠尾草植物上觅食，这些植物靠近中央洞穴，但CP的含量略高（0.2％），ADF的含量低（1％）。鼠尾草的觅食机会> 50％，距洞穴<5.6 m，高度> 0.67 m，CP> 10.4％，ADF <34.95％。矮小兔子对躲避捕食者的需求或减少觅食努力的方法可能会影响选择更近，更大和更富营养的鼠尾草。©2020野生动物协会。y格米兔更喜欢在较高的鼠尾草植物上觅食，这些植物靠近中央洞穴，但CP的含量略高（0.2％），ADF的含量低（1％）。鼠尾草的觅食机会> 50％，距洞穴<5.6 m，高度> 0.67 m，CP> 10.4％，ADF <34.95％。矮小兔子需要躲避捕食者的藏身之需或减少觅食努力的一种方式，可能会影响选择更近，更大，更富营养的鼠尾草。©2020野生动物协会。矮小兔子需要躲避捕食者的藏身之物或减少觅食努力的一种方式，可能会影响到更多的营养密集的鼠尾草。©2020野生动物协会。矮小兔子需要躲避捕食者的藏身之物或减少觅食努力的一种方式，可能会影响到更多的营养密集的鼠尾草。©2020野生动物协会。