Hair density is the most important structural parameter contributing to insulation performance of mammalian pelage, and often is measured in ecophysiological, thermal biological, and evolutionary studies. To date, hair density has been measured using invasive methods on research objects; however, such methods remain challenging despite efforts to increase their ease of use. In this paper, we develop a new method to estimate hair density without skin sampling. We expressed hair density as the inverse of the number of hairs per unit area, that is, the surface area occupied by a single hair (Ah). This area could be further estimated by measuring distances between nearest neighboring hairs (Ln) and calculating the areas of triangles (A) defined by three randomly selected nearest neighboring hairs and representing half of Ah. Empirical tests using 11 skin samples from specimens of six small mammal species showed this to be a simple, lightly invasive, but accurate and widely applicable method.

中文翻译：

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一种估计小型哺乳动物毛皮毛密度的新方法

毛发密度是影响哺乳动物毛皮绝缘性能的最重要的结构参数，通常在生态生理学、热生物学和进化研究中进行测量。迄今为止，已使用侵入性方法对研究对象测量头发密度；然而，尽管努力提高其易用性，但这些方法仍然具有挑战性。在本文中，我们开发了一种无需皮肤采样即可估计毛发密度的新方法。我们将毛发密度表示为单位面积毛发数量的倒数，即单根毛发所占的表面积（Ah）。该区域可以通过测量最近相邻毛发 (Ln) 之间的距离并计算由三个随机选择的最近相邻毛发定义并代表 Ah 的一半的三角形 (A) 的面积来进一步估计。