Biased assessment of thermal properties of birds from estimated body density
Biased assessment of thermal properties of birds from estimated body density
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DOI：
10.1016/j.jtherbio.2023.103472
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发表时间：
2023-01-13
影响因子：
2.7
通讯作者：
Reed, J. Michael
中科院分区：
文献类型：
--
作者：
Eichenwald, Adam J.;Reed, J. Michael
在计算物种的热特性时，通常需要进行参数近似，历史上研究人员在估计体积和密度时假设动物是球形的。我们假设球形模型会导致鸟类密度的显著偏差测量，这些鸟类通常比它们的身高或宽度长，并且这些不准确性会显著改变热模型的输出。我们使用球体和椭圆体体积方程计算了154种鸟类的密度，并将这些估计值相互比较，并与使用更精确的体积位移方法测量的已发表的鸟类密度进行比较。我们还计算了每小时蒸发水分损失占体重的百分比，这是一个已知对鸟类生存至关重要的变量，每个物种计算两次，一次是基于球体的密度，一次是基于椭圆体的密度。我们发现，体积和密度估计公布的密度和那些估计使用椭球体体积方程之间的统计相似，这表明该方法是合适的近似鸟类体积和计算密度。相比之下，球形模型高估了身体体积，因此低估了身体密度。这导致球形方法始终高估了蒸发水损失，作为每小时质量损失的百分比，而不是椭球体方法。这一结果将导致错误地将热条件定性为对特定物种致命，包括高估对气候变化所致温度升高的脆弱性。
Parameter approximation is often necessary when calculating species thermal properties, and researchers his-torically have assumed animals are spherical when estimating volume and density. We hypothesized that a spherical model would result in significantly biased measures of density for birds, which are generally longer than they are tall or wide, and that these inaccuracies would significantly alter the outputs of thermal models. We calculated the densities of 154 bird species using sphere and ellipsoid volume equations and compared these estimates to one another and to published bird densities measured using more exact volume displacement methods. We also calculated evaporative water loss as a percentage of body mass per hour, a variable known to be critical for bird survival, twice for each species, once with the sphere-based density and once with the ellipsoid-based density. We found that volume and density estimates were statistically similar between published densities and those estimated using the ellipsoid volume equation, suggesting that this method is suitable for approximating bird volume and calculating density. In contrast, the spherical model overestimated body volume and therefore underestimated body densities. This resulted in the spherical approach consistently overestimating evaporative water loss as a percent of mass lost per hour than the ellipsoid approach. This outcome would result in mischaracterizing thermal conditions as lethal for a given species, including overestimating vulnerability to increased temperatures due to climate change.