Body condition indices and related metrics can help assess habitat quality and other ecological processes, and ideally, these metrics are based on measures of lipids directly extracted from the species of interest. In recent decades, barred owls (Strix varia) have become a species of conservation concern as they invaded older forests of the US Pacific Northwest, and caused population declines of the closely related and federally threatened northern spotted owl (Strix occidentalis caurina). A simple and effective measure of barred owl body condition could help to understand how habitat quality varies within their new range, which in turn can inform their management and other aspects of their ecology. Using 77 barred owl carcasses collected during experimental removals in Washington and Oregon, USA, we measured the amount of lipid in each specimen with proximate body composition analysis. We then fit and compared (with adjusted R2 values) alternative linear regression models to estimate the percent lipids in dry mass of the owls based on morphometric body condition indices, a qualitative fat score of subcutaneous breast fat, sex and the time of year females were collected (relative to egg production). Adjusted R2 values for all models ranged from 0.49 to 0.87, with the best model including mass divided by foot-pad length, fat score, sex and the time of year a female was collected. Most models generated comparable estimates of percent lipids at a population level and we provided correction factors to apply these models when used with live barred owls, allowing for site-specific comparisons of body condition among individuals inhabiting a diversity of environmental conditions.

中文翻译：

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利用根据直接测量近似身体成分开发的预测模型来估计条纹猫头鹰（Strix varia）的脂肪含量。

身体状况指数和相关指标可以帮助评估栖息地质量和其他生态过程，理想情况下，这些指标基于直接从感兴趣物种中提取的脂质测量值。近几十年来，斑纹鸮（Strix varia）入侵美国太平洋西北部的古老森林，并导致与联邦有密切关系的北方斑点鸮（Strix occidentalis caurina）的数量下降，因此它们已成为受保护的物种。对条纹猫头鹰身体状况进行简单有效的测量可以帮助了解栖息地质量在新范围内的变化，从而可以为它们的管理和生态的其他方面提供信息。我们利用在美国华盛顿和俄勒冈州实验采集的 77 具斑纹猫头鹰尸体，通过近似身体成分分析测量了每个样本中的脂质含量。然后，我们拟合并比较（调整后的 R2 值）替代线性回归模型，以根据形态测量身体状况指数、皮下乳房脂肪的定性脂肪评分、性别和雌性一年中的时间来估计猫头鹰干重中的脂质百分比。收集（相对于产蛋量）。所有模型的调整后 R2 值范围为 0.49 至 0.87，最佳模型包括质量除以足垫长度、脂肪分数、性别和收集女性的一年时间。大多数模型都生成了种群水平上脂质百分比的可比估计值，并且我们提供了校正因子，以便在与活斑猫头鹰一起使用时应用这些模型，从而可以对居住在不同环境条件下的个体之间的身体状况进行特定地点的比较。