Because birds are frequently detected by sound, autonomous audio recorders (called automated recording units or ARUs) are now an established tool in addition to in-person observations for monitoring the status and trends of bird populations. ARUs have been evaluated and applied during breeding seasons, and to monitor the nocturnal flight calls of migrating birds. However, birds behave differently during migration than during the breeding season. Here we present a method for using ARUs to monitor land birds during the migration period in remote habitats. We conducted in-person point counts next to continuously recording ARUs, and compared estimates of the number of species detected and focal species relative abundance from point counts and ARUs. We used a desk-based audio bird survey method for processing audio recordings, which does not require automated species identification algorithms. We tested two methods of using extended duration ARU recording: surveying consecutive minutes and surveying randomly selected minutes. Desk-based surveys using randomly selected minutes from extended duration ARU recordings performed similarly to point counts, and better than desk-based surveys using consecutive minutes from ARU recordings. Surveying randomly selected minutes from ARUs provided estimates of relative abundance that were strongly correlated with estimates from point counts and successfully showed the increase in abundance associated with migration timing. Randomly selected minutes also provided estimates of the number of species present that were comparable to estimates from point counts. Our results suggest that ARUs are an effective way to track migration timing and intensity in remote or seasonally inaccessible habitat during spring migration. Additional testing is needed to determine the efficacy of our methods during fall migration, and at more southerly latitudes. We recommend that desk-based surveys use randomly sampled minutes from extended duration ARU recordings, rather than using consecutive minutes from recordings. Our methods can be immediately applied by researchers with the skills to conduct point counts, with no additional expertise necessary in automated species identification algorithms.

中文翻译：

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监测偏远栖息地的迁徙时间：评估长时间录音的价值

由于鸟类经常被声音检测到，自动录音机（称为自动记录装置或 ARU）现在是一种既定工具，除了用于监测鸟类种群状况和趋势的亲自观察之外。ARU 已在繁殖季节进行评估和应用，并用于监测候鸟的夜间飞行呼叫。然而，鸟类在迁徙期间的行为与繁殖季节不同。在这里，我们提出了一种在偏远栖息地的迁徙期间使用 ARU 监测陆地鸟类的方法。我们在连续记录 ARU 旁边进行了面对面的点计数，并比较了从点计数和 ARU 中检测到的物种数量和焦点物种相对丰度的估计值。我们使用基于桌面的音频鸟类调查方法来处理录音，这不需要自动物种识别算法。我们测试了两种使用延长持续时间 ARU 记录的方法：调查连续分钟和调查随机选择的分钟。使用从延长的持续时间 ARU 记录中随机选择的分钟的基于桌面的调查与点计数相似，并且比使用连续的 ARU 记录的分钟的基于桌面的调查更好。调查从 ARU 中随机选择的分钟提供了相对丰度的估计，这些估计与点计数的估计密切相关，并成功地显示了与迁移时间相关的丰度增加。随机选择的分钟还提供了与点计数估计值相当的物种数量估计值。我们的结果表明，ARU 是在春季迁徙期间跟踪偏远或季节性无法进入的栖息地的迁徙时间和强度的有效方法。需要额外的测试来确定我们的方法在秋季迁移期间以及在更南纬地区的有效性。我们建议基于案头的调查使用从持续时间较长的 ARU 录音中随机抽样的分钟数，而不是使用连续的录音分钟数。我们的方法可以立即被具有进行点计数技能的研究人员应用，而无需额外的自动物种识别算法专业知识。我们建议基于案头的调查使用从持续时间较长的 ARU 录音中随机抽样的分钟数，而不是使用连续的录音分钟数。我们的方法可以立即被具有进行点计数技能的研究人员应用，而无需额外的自动物种识别算法专业知识。我们建议基于案头的调查使用从持续时间较长的 ARU 录音中随机抽样的分钟数，而不是使用连续的录音分钟数。我们的方法可以立即被具有进行点计数技能的研究人员应用，而无需额外的自动物种识别算法专业知识。